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Background: Nephronophthisis (NPH) comprises a heterogeneous group of inherited renal ciliopathies clinically characterized by progressive kidney failure. So far, definite diagnosis is based on molecular testing only. Here, we studied the feasibility of NPHP1 and NPHP4 immunostaining of nasal epithelial cells to secure and accelerate the diagnosis of NPH. Methods: Samples of 86 individuals with genetically determined renal ciliopathies were analyzed for NPHP1 localization using immunofluorescence microscopy (IF). A sub-cohort of 35 individuals was also analyzed for NPHP4 localization. Western blotting was performed to confirm IF results. Results: NPHP1 and NPHP4 were both absent in all individuals with disease-causing NPHP1 variants including one with a homozygous missense variant (c.1027G > A; p.Gly343Arg) formerly classified as a "variant of unknown significance." In individuals with an NPHP4 genotype, we observed a complete absence of NPHP4 while NPHP1 was severely reduced. IF results were confirmed by immunoblotting. Variants in other genes related to renal ciliopathies did not show any impact on NPHP1/NPHP4 expression. Aberrant immunostaining in two genetically unsolved individuals gave rise for a further genetic workup resulting in a genetic diagnosis for both with disease-causing variants in NPHP1 and NPHP4, respectively. Conclusions: IF of patient-derived respiratory epithelial cells may help to secure and accelerate the diagnosis of nephronophthisis—both by verifying inconclusive genetic results and by stratifying genetic diagnostic approaches. Furthermore, we provide in vivo evidence for the interaction of NPHP1 and NPHP4 in a functional module. [ABSTRACT FROM AUTHOR]

Nagashima-type palmoplantar keratosis (NPPK) is a relatively common autosomal recessive dermatosis characterized by well-defined diffuse erythema and non-destructive hyperkeratosis on the palmoplantar areas, with swelling and whitening when exposed to water. The pathogenesis of NPPK can be attributable to altered structure and function of SERPINB7, environmental factors, barrier dysfunction and inflammatory response. There is no specific and standardized therapy for this disorder. Topical treatment is primary therapy although systemic drugs or surgery can be used for severe cases. Gentamicin, a targeted therapy for the disease, has shown some potential, but more clinical studies are still needed to verify its efficacy and safety. The aim of this review is to summarize the causative gene, pathogenesis and therapeutic strategies of NPPK. [ABSTRACT FROM AUTHOR]

Background: To investigate whether the novel mutation of PKHD1 could cause polycystic kidney disease by affecting splicing with a recessive inheritance pattern. Methods: A nonconsanguineous Chinese couple with two recurrent pregnancies showed fetal enlarged echogenic polycystic kidney and oligoamnios were recruited. Pedigree WES, minigene splicing assay experiment and following bioinformatics analysis were performed to verify the effects, and inheritance pattern of diseasing-causing mutations. Results: WES revealed that both fetuses were identified as carrying the same novel mutation c.3592_3628 + 45del, p.? and c.11207 T>C, p.(Ile3736Thr) in the PKHD1 gene (NM_138694.4), which inherited from the father and mother respectively. Both bioinformatic method prediction and minigene splicing assay experience results supported the mutation c.3592_3628 + 45del, p.? affects the splicing of the PKHD1 transcript, resulting in exon 31 skipping. Another missense mutation c.11207 T>C, p.(Ile3736Thr) has a low frequency in populations and is predicted to be deleterious by bioinformatic methods. Conclusion: These findings provide a direct clinical and functional evidence that the truncating mutations of the PKHD1 gene could lead to more severe phenotypes, and cause ARPKD as a homozygous or compound heterozygous pattern. Our study broadens the variant spectrum of the PKHD1 gene and provides a basis for genetic counseling and diagnosis of ARPKD. [ABSTRACT FROM AUTHOR]

Homozygous deletion of NPHP1 can lead to isolated nephronophthisis (NPHP) and syndromic disorders. However, the phenotype of scalp tumor and hydroureteronephrosis in NPHP patients with homozygous deletion of NPHP1 has not been reported. Clinical data, laboratory results, and genetic testing of 4 NPHP patients were collected. Examination of their eyes, heart, and urinary tract and of their hepatobiliary, skeletal, and central nervous systems was evaluated. Isolated NPHP was observed in 1 case, and syndromic disorders were observed in the other 3 patients. Their syndromic disorders showed NPHP combined with central nervous system defects, eye involvement, scalp tumor, arachnoid cyst, or hydroureteronephrosis. Large homozygous deletions covering the whole NPHP1 gene locus were identified in all 4 patients. We report a novel phenotype of scalp tumor and hydroureteronephrosis in NPHP patients with homozygous deletion of NPHP1, paving an avenue for further research on NPHP1 -associated deformity in the skin and the urinary system. [ABSTRACT FROM AUTHOR]

Introduction: Nephronophthisis (NPHP) is a tubulointerstitial kidney disorder with an autosomal recessive inheritance pattern. Its genetic heterogeneity contributes to phenotype variability. The most frequent etiology of juvenile nephronophthisis is a mutation in the nephronophthisis type 1 (NPHP1) gene. This study aimed to evaluate the genotype-phenotype correlation in NPHP1 gene mutation. Methods: A multicenter retrospective study was performed over 20 years from 1998 to 2018 to describe the clinical, biological, and radiological features associated with the large deletion NPHP1 gene in 32 patients. Results: The incidence of NPHP1 was 1.6/204041. Eighty-one percent of our patients were born out of consanguineous marriages. The mean age at diagnosis was 14 ± 7 years. The patients were divided into three groups: isolated nephronophthisis (72%), syndromic nephronophthisis (19%), and patients without recognizable syndrome (9%). Intrafamilial and geographical variability was observed in syndrome diagnoses and in age at the onset of CKD stage 5. Genotype frequency varied between 50% and 100% in genealogical data. Juvenile (47%), adolescent (37%), and adult (13%) clinical forms have been distinguished by the onset of CKD stage 5. The five-year survival rate of renal transplantation was 80%. Conclusion: Given the broad clinical spectrum of NPHP1 associated with the large deletion of the NPHP1 gene, no genotype-phenotype correlation could be established. [ABSTRACT FROM AUTHOR]

A quiz concerning 5‑year‑old girl with kidney impairment and severe anemia.

Background: Autosomal recessive polycystic kidney disease is a cystic kidney disease with early onset and clinically characterized by enlarged echogenic kidneys, hypertension, varying degrees of kidney dysfunction, and liver fibrosis. It is most frequently caused by sequence variants in the PKHD1 gene, encoding fibrocystin. In more rare cases, sequence variants in DZIP1L are seen, encoding the basal body protein DAZ interacting protein 1-like protein (DZIP1L). So far, only four different DZIP1L variants have been reported. Methods: Four children from three consanguineous families presenting with polycystic kidney disease were selected for targeted or untargeted exome sequencing. Results: We identified two different, previously not reported homozygous DZIP1L sequence variants: c.193 T > C; p.(Cys65Arg), and c.216C > G; p.(Cys72Trp). Functional analyses of the c.216C > G; p.(Cys72Trp) variant indicated mislocalization of mutant DZIP1L. Conclusions: In line with published data, our results suggest a critical role of the N-terminal domain for proper protein function. Although patients with PKHD1-associated autosomal recessive polycystic kidney disease often have liver abnormalities, none of the present four patients showed any clinically relevant liver involvement. Our data demonstrate the power and efficiency of next-generation sequencing-based approaches. While DZIP1L-related polycystic kidney disease certainly represents a rare form of the disease, our results emphasize the importance of including DZIP1L in multigene panels and in the data analysis of whole-exome sequencing for cystic kidney diseases. A higher resolution version of the Graphical abstract is available as Supplementary information [ABSTRACT FROM AUTHOR]

Context: The syndrome of adrenal insufficiency, obesity, and red hair is a rare autosomal recessive disorder. The majority of disease-causing variants associated with the syndrome are located in the coding region of the POMC gene. Objective: This work describes 7 unrelated patients who shared a novel homozygous mutation in the 5′-untranslated region (UTR) of the POMC gene and functionally characterize this novel variant. Methods: Whole-exome sequencing (WES) with autozygosity mapping, Sanger sequencing, model expression system studies, and RNA sequencing were used for identification of the disease-causing variant and its subsequent functional characterization. Seven unrelated patients of the Perm Tatar ethnic group presented with hypoglycemia and excessive weight gain, low plasma adrenocorticotropin, and cortisol. Five of 7 children had red hair; 6 of 7 patients also showed signs of bronchial obstruction. Results: WES showed shared autozygosity regions overlapping the POMC gene. Sanger sequencing of the POMC 5′-UTR detected a homozygous variant chr2:25391366C >T (hg19) at the splice donor site of intron 1. As demonstrated by the model expression system, the variant led to a significant decrease in the POMC messenger RNA level. Analyses of the patients’ haplotypes were suggestive of the founder effect. We estimate that the mutation must have occurred at least 4.27 generations ago (95% CI, 0.86-7.67). Conclusion: This report presents a new molecular mechanism of POMC deficiency and contributes to the information on phenotypic variability in patients with this disorder. [ABSTRACT FROM AUTHOR]

Background: There is a high prevalence of rare genetic disorders in the Middle East, and their study provides unique clinical and genetic insights. Autosomal recessive polycystic kidney disease (ARPKD) is one of the leading causes of kidney and liver-associated morbidity and mortality in Oman. We describe the clinical and genetic profile of cohort of ARPKD patients.Methods: We studied patients with a clinical diagnosis of ARPKD (n = 40) and their relatives (parents (n = 24) and unaffected siblings (n = 10)) from 32 apparently unrelated families, who were referred to the National Genetic Centre in Oman between January 2015 and December 2018. Genetic analysis of PKHD1 if not previously known was performed using targeted exon PCR of known disease alleles and Sanger sequencing.Results: A clinical diagnosis of ARPKD was made prenatally in 8 patients, 21 were diagnosed during infancy (0-1 year), 9 during early childhood (2-8 years) and 2 at later ages (9-13 years). Clinical phenotypes included polycystic kidneys, hypertension, hepatic fibrosis and splenomegaly. Twenty-four patients had documented chronic kidney disease (median age 3 years). Twenty-four out of the 32 families had a family history suggesting an autosomal recessive pattern of inherited kidney disease, and there was known consanguinity in 21 families (66%). A molecular genetic diagnosis with biallelic PKHD1 mutations was known in 18 patients and newly identified in 20 other patients, totalling 38 patients from 30 different families. Two unrelated patients remained genetically unsolved. The different PKHD1 missense pathogenic variants were: c.107C > T, p.(Thr36Met); c.406A > G, p.(Thr136Ala); c.4870C > T, p.(Arg1624Trp) and c.9370C > T, p.(His3124Tyr) located in exons 3, 6, 32 and 58, respectively. The c.406A > G, p.(Thr136Ala) missense mutation was detected homozygously in one family and heterozygously with a c.107C > T, p.(Thr36Met) allele in 5 other families. Overall, the most commonly detected pathogenic allele was c.107C > T; (Thr36Met), which was seen in 24 families.Conclusions: Molecular genetic screening of PKHD1 in clinically suspected ARPKD cases produced a high diagnostic rate. The limited number of PKHD1 missense variants identified in ARPKD cases suggests these may be common founder alleles in the Omani population. Cost effective targeted PCR analysis of these specific alleles can be a useful diagnostic tool for future cases of suspected ARPKD in Oman. [ABSTRACT FROM AUTHOR]

Cystic kidney diseases are a very heterogeneous group of chronic kidney diseases. The diagnosis is usually based on clinical and ultrasound characteristics and the final diagnosis is often difficult to be made. Next-generation sequencing (NGS) may help the clinicians to find the correct final diagnosis. The aim of our study was to test the diagnostic yield of NGS and its ability to improve the diagnosis precision in a heterogeneous group of children with cystic kidney diseases. Next-generation sequencing of genes responsible for the formation of cystic kidneys was performed in 31 unrelated patients with various clinically diagnosed cystic kidney diseases gathered at the Department of Pediatrics of Motol University Hospital in Prague between 2013 and 2018. The underlying pathogenic variants were detected in 71% of patients (n = 22), no or only one (in case of autosomal recessive inheritance) pathogenic variant was found in 29% of patients (n = 9). The result of NGS correlated with the clinical diagnosis made before the NGS in 55% of patients (n = 17), in the remaining 14 children (45%) the result of NGS revealed another type of cystic kidney disease that was suspected clinically before or did not find causal mutation in suspected genes. The most common unexpected findings were variants in nephronophthisis (NPHP) genes in children with clinically suspected autosomal recessive polycystic kidney disease (ARPKD, n = 4). Overall, 24 pathogenic or probably pathogenic variants were detected in the PKHD1 gene, 8 variants in the TMEM67 gene, 4 variants in the PKD1 gene, 2 variants in the HNF1B gene and 2 variants in BBS1 and NPHP1 genes, respectively. NGS is a valuable tool in the diagnostics of various forms of cystic kidney diseases. Its results changed the clinically based diagnoses in 16% (n = 5) of the children. [ABSTRACT FROM AUTHOR]

Background: While typical ultrasound patterns of ciliopathy-related cystic kidney diseases have been described in children, ultrasound findings can overlap between different diseases and atypical patterns exist. In this study, we assessed the presence of the "salt and pepper" pattern in different renal ciliopathies and looked for additional ultrasound features. Methods: This single-center, retrospective study included all patients with a molecular-proven diagnosis of renal ciliopathy, referred to our center between 2007 and 2017. Images from the first and follow-up ultrasound exams were reviewed. Basic ultrasound features were grouped into patterns and compared to genetic diagnoses. The "salt and pepper" aspect was described as enlarged kidneys with heterogeneous, increased parenchymal echogenicity. Results: A total of 41 children with 5 different renal ciliopathies were included (61% male; median age, 6 years [range, 3 days to 17 years]). The "salt and pepper" pattern was present in 14/15 patients with an autosomal recessive polycystic kidney disease (ARPKD). A similar pattern was found in 1/4 patients with an autosomal dominant polycystic kidney disease and in 1/11 patients with HNF1B mutation. Additional signs found were areas of cortical sparing, comet-tail artifacts, and color comet-tail artifacts. Conclusion: Although the "salt and pepper" ultrasound pattern is predominantly found in ARPKD, it may be detected in other ciliopathies. The color comet-tail artifact is an interesting sign when suspecting a renal ciliopathy in case of enlarged hyperechoic kidneys with no detectable microcysts on B-mode grayscale ultrasound. [ABSTRACT FROM AUTHOR]

Congenital hepatic fibrosis (CHF) often accompanies autosomal recessive polycystic kidney disease (ARPKD), which stems from a PKHD1 gene mutation. The aim of this study was to clarify the prognosis of children with CHF who received living donor liver transplantation (LDLT) from donors who might be heterozygous carriers of a hepatorenal fibrocystic disease. Fourteen children with CHF who underwent LDLT at our center were enrolled. Eight and two patients had ARPKD and nephronophthisis, respectively. Eight of the donors were the recipients' fathers, and six donors were their mothers. We examined the histological and radiological findings of the donor livers and complications in the recipients following the liver transplantation. Seven of the donor livers presented morphological abnormalities of the bile ducts. Abdominal computed tomography revealed liver cysts in eight donors. One recipient underwent re‐LT for graft failure due to rejection. Three patients presented with rejection, and one presented with sepsis. The overall survival rate was 100% and the original graft survival rate was 93%. In conclusion, the prognosis of recipients who received a LDLT from their parents for CHF was excellent. However, the morphology of half the donor livers was abnormal. Careful follow‐up is needed to ensure long‐term graft survival. [ABSTRACT FROM AUTHOR]

Osteopetrosis refers to a group of rare genetic bone diseases that are clinically characterized by increased bone mass and fragility. The principal pathogenic defect in patients with chloride channel 7 (CLCN7) gene-dependent osteopetrosis is reduced osteoclast activity, which leads to decreased bone resorption. Mutations in the CLCN7 gene result in autosomal dominant osteopetrosis type II (ADO-II), autosomal recessive osteopetrosis (ARO) and intermediate ARO (IARO). In the present study, eight mutations in the CLCN7 gene were identified in six patients with familial osteopetrosis and one patient with sporadic osteopetrosis. Heterozygous mutations c.856C>T (R286W), c.2236T>G (Y746D), c.296A>G (Y99C) and c.937G>A (E313K), and a splice mutation (c.2232-2A>G) in the CLCN7 gene were detected in patients with ADO-II. A homozygous mutation c.2377G>C (G793R), and a compound heterozygous mutation c.1409C>T (P470L) and c.647_648dupTG (K217X) were detected in two Chinese families with IARO. Among these mutations, two heterozygous mutations (c.2236T>G and c.2232-2A>G), one homozygous mutation (c.2377G>C) and the compound heterozygous mutation (c.1409C>T and c.647_648dupTG) are novel, to the best of our knowledge. The present findings not only broaden the allelic spectrum of CLCN7 mutations, but also provide increased knowledge of the clinical phenotypes observed in Chinese patients with osteopetrosis. [ABSTRACT FROM AUTHOR]

Abstract Primary autosomal recessive microcephaly (MCPH) is a rare hereditary disease characterized by congenitally small with brain circumference of the head below 3 standard deviations (SD). By far, 18 MCPH genes have been reported to be associated with the disease. SASS6 gene functioned in assembly of centrioles that the majority of MCPH genes present at the centrosome. There was only research reporting a homozygous missense mutation in SASS6 gene detected in a consanguineous Pakistani family. By conducting Whole-exome sequencing (WES) and Sanger sequencing on the family trio, we identified two novel splice site mutations c.127-13A>G and c.1867+2T>A in compound heterozygous hereditary form in the SASS6 gene. The two mutations were confirmed to alter mRNA splicing by RT-PCR assay. Our finding supported the role of SASS6 in the pathogenesis of microcephaly, expanding mutation spectrums and contributing to understanding of molecular mechanisms of MCPH. Highlights • We report SASS6 compound heterozygous mutations in a Chinese family with MCPH. • Our analysis is the second mutation report of SASS6 gene of the world. • c.127-13A>G and c.1867+2T>A are novel splice site mutations of SASS6. [ABSTRACT FROM AUTHOR]

Introduction: DNA testing for autosomal recessive disease mutations in many dog breeds is now relatively commonplace. There have, however, been few efforts made to determine changes in the frequency of disease causing mutations as a result of probable selection based on the results of DNA testing. This study makes use of genotype data from both DNA test results reported to the UK Kennel Club and where known from a ‘hereditary status’ (where a definitive genotype may be inferred and ascribed based on known parental genotypes) to do so. Results: The results, using all known genotype data, show a general and sizeable decline in disease causing mutation frequency across eight diseases in eight breeds (by between 12–86% in dogs born 2–4 years after publication of the mutation, and by nearly 90% or more in those born 8–10 years after). In contrast, data from test results only, while revealing an almost complete and immediate end to the production of affected individuals, show little general decline in either the derived mutation frequency or the proportion of heterozygote carriers. It appears that the numerical size of the breed is an important determinant on the rate of uptake of a DNA test (as judged by the proportion of a breed born four years after publication of the disease-causing mutation with a known genotype). Conclusion: These results show that dog breeders appear to be incorporating the results of DNA testing into their selection strategies to successfully decrease the frequency of the mutation. It is shown that use of DNA test result data alone does not reveal such trends, possibly as some breeders undertake testing to determine clear stock which can then be used to produce future disease-free generations in the knowledge they are not carrying the disease causing mutation. [ABSTRACT FROM AUTHOR]

Mutations in ATP13A2 cause Kufor-Rakeb syndrome, an autosomal recessive form of juvenile-onset atypical Parkinson's disease (PD). Recent work tied ATP13A2 to autophagy and other cellular features of neurodegeneration, but how ATP13A2 governs numerous cellular functions in PD pathogenesis is not understood. In this study, the ATP13A2-deficient mouse developed into aging-dependent phenotypes resembling those of autophagy impairment. ATP13A2 deficiency impaired autophagosome-lysosome fusion in cultured cells and in in vitro reconstitution assays. In ATP13A2-deficient cells or Drosophila melanogaster or mouse tissues, lysosomal localization and activity of HDAC6 were reduced, with increased acetylation of tubulin and cortactin. Wild-type HDAC6, but not a deacetylase-inactive mutant, restored autophagosome-lysosome fusion, antagonized cortactin hyperacetylation, and promoted lysosomal localization of cortactin in ATP13A2-deficient cells. Mechanistically, ATP13A2 facilitated recruitment of HDAC6 and cortactin to lysosomes. Cortactin overexpression in cultured cells reversed ATP13A2 deficiency-associated impairment of autophagosome-lysosome fusion. PD-causing ATP13A2 mutants failed to rescue autophagosome-lysosome fusion or to promote degradation of protein aggregates and damaged mitochondria. These results suggest that ATP13A2 recruits HDAC6 to lysosomes to deacetylate cortactin and promotes autophagosome-lysosome fusion and autophagy. This study identifies ATP13A2 as an essential molecular component for normal autophagy flux in vivo and implies potential treatments targeting HDAC6-mediated autophagy for PD. [ABSTRACT FROM AUTHOR]

We present a family with two members affected by hyperekplexia and two unaffected members. All exons in the glycine receptor alpha 1 subunit gene (GLRA1) were sequenced in all four family members. Our index patient harbored a novel nonsense mutation (p.Trp314*; rs867618642) in the transmembrane domain three of the GLRA1 and a novel missense variant in the NH2-terminal part (p.Val67Met; rs142888296). After development of tolerance for the effective treatment with clobazam a drug holiday led to a sustained restoration of the treatment response. [ABSTRACT FROM AUTHOR]

Introduction: A wide variety of mutations are spread throughout the PKHD1 gene, which encodes a 4074-bp amino acid protein, namely fibrocystin/polyductin, and is responsible for all features of autosomal recessive polycystic kidney disease (ARPKD). Autosomal recessive polycystic kidney disease is a hereditary early-onset form of polycystic kidney disease characterized by fusiform dilation of collecting ducts and congenital hepatic fibrosis. The highest level of PKDH1 expression is in the kidneys of fetus and adults, suggesting the functionally importance of the gene in the mature kidney in addition to its role in kidney development.Materials and Methods: Mutational analysis of the PKHD1 gene was performed in 11 families with a history of 1 to 6 fetuses or children affected by ARPKD, which either were aborted or died shortly after birth. Analyses were done using the Next Generation sequencing and Sanger sequencing techniques.Results: Four novel mutations, including c.6469C>T, c.9218 G>A, c.10456T>C, and c.8863C>G, and 3 previously reported ones, including c.9524A>G, c.1095G>A, c.1123C>T, were identified.Conclusions: In view of high consanguineous marriages in Iranian population, the frequency of disease is expected to be higher than the world average. [ABSTRACT FROM AUTHOR]

Background: Autosomal recessive polycystic kidney disease (ARPKD) is genetically one of the least heterogeneous ciliopathies, resulting primarily from mutations of PKHD1. Nevertheless, 13-20% of patients diagnosed with ARPKD are found not to carry PKHD1 mutations by sequencing. Here, we assess whether PKHD1 copy number variations or second locus mutations explain these cases.Methods: Thirty-six unrelated patients with the clinical diagnosis of ARPKD were screened for PKHD1 point mutations and copy number variations. Patients without biallelic mutations were re-evaluated and screened for second locus mutations targeted by the phenotype, followed, if negative, by clinical exome sequencing.Results: Twenty-eight patients (78%) carried PKHD1 point mutations, three of whom on only one allele. Two of the three patients harbored in trans either a duplication of exons 33-35 or a large deletion involving exons 1-55. All eight patients without PKHD1 mutations (22%) harbored mutations in other genes (PKD1 (n = 2), HNF1B (n = 3), NPHP1, TMEM67, PKD1/TSC2). Perinatal respiratory failure, a kidney length > +4SD and early-onset hypertension increase the likelihood of PKHD1-associated ARPKD. A patient compound heterozygous for a second and a last exon truncating PKHD1 mutation (p.Gly4013Alafs*25) presented with a moderate phenotype, indicating that fibrocystin is partially functional in the absence of its C-terminal 62 amino acids.Conclusions: We found all ARPKD cases without PKHD1 point mutations to be phenocopies, and none to be explained by biallelic PKHD1 copy number variations. Screening for copy number variations is recommended in patients with a heterozygous point mutation. [ABSTRACT FROM AUTHOR]

Complex balanced autosomal translocation is rare and can lead to impaired spermatogenesis in males; however, its effects on oligozoospermia have rarely been reported. We report here two cases of rare complex balanced translocation in men with infertility. The karyotype of the first case was 46,XY,der(1)t(1;12)(p22;p11.2)ins(9;1)(p24;q25q23),der(9)ins(9;1),der(12)t(1;12)·ish der(1)t(1;12)(RP11-636B1+;RP11-659D23+)ins(9;1)(RP11-118P13+),der(9)ins(9;1),der(12)t(1;12). And the patient showed severe oligozoospermia with adult schizophrenia without other abnormalities. The karyotype of the second patient was 46,XY,der(5)t(5;11)(q14;p11.2),der(11)t(11;18)(p11.2;q11.2),der(18)t(5,18)(q14;p11.3)add(18)(q11.2?)·ish der(5)t(5;11)(RP11-846K3+,RP11-89B9+),der(11)t(11;18)(RP11-89B9-,RP11-170L12+,RP11-469N6+),der(18)t(5;18)(RP11-125L2+,RP11-29M13+)add(18)(q11.2?), and the patient displayed severe oligozoospermia without other abnormalities. The two cases were verified by fluorescent in situ hybridization, and no abnormalities were found by genome-wide copy number variation analysis. To our knowledge, these two cases of complex autosomal karyotypes have not been reported previously. Although rare, these cases suggest that complex balanced translocations may be important causes of oligozoospermia. We speculate that the balanced translocation hinders germ cell meiosis and causes impaired spermatogenesis. Accordingly, the two reported patients have very low probabilities of giving birth to a normal child; therefore, we suggest choosing donor semen or adopting a child. [ABSTRACT FROM AUTHOR]

Objective(s): Targeted next-generation sequencing (NGS) provides a consequential opportunity to elucidate genetic factors in known diseases, particularly in profoundly heterogeneous disorders such as non-syndromic hearing loss (NSHL). Hearing impairments could be classified into syndromic and nonsyndromic types. This study intended to assess the significance of mutations in these genes to the autosomal recessive/dominant non-syndromic genetic load among Iranian families. Materials and Methods: Two families were involved in this research and two patients were examined by targeted next-generation sequencing. Here we report two novel mutations in the MYO7A and EYA1 genes in two patients detected by targeted NGS. They were confirmed by Sanger sequencing and quantitative real-time PCR techniques. Results: In this investigation, we identified a novel mutation in MYO7A, c.3751G>C, p.A1251P, along with another previously identified mutation (c.1708C>T) in one of the cases. This mutation is located in the MYTH4 protein domain which is a pivotal domain for the myosin function. Another finding in this research was a novel de-novo deletion which deletes the entire EYA1 coding region (EX1-18 DEL). Mutations in EYA1 gene have been found in branchiootorenal (BOR) syndrome. Interestingly the patient with EYA1 deletion did not show any other additional clinical implications apart from HL. This finding might argue for the sole involvement of EYA1 function in the mechanism of hearing. Conclusion: This investigation exhibited that the novel mutations in MYO7A, c.3751G>C, p.A1251P, and EYA1, EX1-18 DEL, were associated with NSHL. Our research increased the mutation spectrum of hearing loss in the Iranian population. [ABSTRACT FROM AUTHOR]

Background: Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic cause of end-stage renal disease. Although imaging techniques are a means of accurate diagnosis when the cysts appear in the third or fourth decades of the patient's life, they are of little value for early diagnosis. Genetic tests are required for preimplantation genetic diagnosis, decision-making for kidney donation to an affected relative. Although mutation of the polycystic kidney disease (PKD1) gene is solely responsible for the most cases of ADPKD, direct genetic testing is limited by the large size of this gene and the presence of many mutations without hot spots. Therefore, indirect diagnosis with linkage analysis using informative microsatellite markers has been suggested. Materials and Methods: In this study, we assessed the informativeness of the PKD1 gene markers D16S475, D16S291, and D16S3252 in Iranian population. Using specific primers, fluorescent polymerase chain reaction (PCR) was performed on genomic DNA extracted from fifty unrelated individuals. PCR products were analyzed by the ALFexpress DNA sequencer system, and the number and frequency of alleles were determined to calculate the heterozygosity (HET) and polymorphism information content (PIC) values. Results: We found that the HET and PIC values for the D16S475 marker are 0.92 and 0.91, respectively. These two values are 0.82 and 0.80 for D16S291 and 0.50 and 0.47 for D16S3252, respectively. Conclusion: Based on this data, D16S475 and D16S291 are highly and D16S3252 is moderately informative for indirect genetic diagnosis of PKD1 mutations in this population. [ABSTRACT FROM AUTHOR]

Extracellular vesicles, such as exosomes and microvesicles, are host cell-derived packages of information that allow cell-cell communication and enable cells to rid themselves of unwanted substances. The release and uptake of extracellular vesicles has important physiological functions and may also contribute to the development and propagation of inflammatory, vascular, malignant, infectious and neurodegenerative diseases. This Review describes the different types of extracellular vesicles, how they are detected and the mechanisms by which they communicate with cells and transfer information. We also describe their physiological functions in cellular interactions, such as in thrombosis, immune modulation, cell proliferation, tissue regeneration and matrix modulation, with an emphasis on renal processes. We discuss how the detection of extracellular vesicles could be utilized as biomarkers of renal disease and how they might contribute to disease processes in the kidney, such as in acute kidney injury, chronic kidney disease, renal transplantation, thrombotic microangiopathies, vasculitides, IgA nephropathy, nephrotic syndrome, urinary tract infection, cystic kidney disease and tubulopathies. Finally, we consider how the release or uptake of extracellular vesicles can be blocked, as well as the associated benefits and risks, and how extracellular vesicles might be used to treat renal diseases by delivering therapeutics to specific cells. [ABSTRACT FROM AUTHOR]

Objective Locus and allellic heterogeneity in polycystic kidney disease (PKD) is a great challenge in precision diagnosis. We aim to establish comprehensive methods to distinguish the pathogenic mutations from the variations in PKD1 , PKD2 and PKHD1 genes in a limited time and lay the foundation for precisely prenatal diagnosis, preimplantation genetic diagnosis and presymptom diagnosis of PKD. Methods Nested PCR combined with direct DNA sequencing were used to screen variations in PKD1 , PKD2 and PKHD1 genes. The pathogenicity of de novel variations was assessed by the comprehensive methods including clinic data and literature review, databases query, analysis of co-segregation of the variants with the disease, variant frequency screening in the population, evolution conservation comparison, protein structure analysis and splice sites predictions. Results 17 novel mutations from 15 Chinese Han families were clarified including 10 mutations in PKD1 gene and 7 mutations in PKHD1 gene. The novel mutations were classified as 4 definite pathogenic, 2 highly likely pathogenic, 4 likely pathogenic, 7 indeterminate by the comprehensive analysis. The results were verified the truth by the follow-up visits. Conclusions The comprehensive methods may be useful in distinguishing the pathogenic mutations from the variations in PKD1 , PKD2 and PKHD1 genes for prenatal diagnosis and presymptom diagnosis of PKD. Our results also enriched PKD genes mutation spectrum and evolved possible genotype-phenotype correlations of Chinese Han population. [ABSTRACT FROM AUTHOR]

Mutations in the ganglioside-induced differentiation-associated protein 1 gene ( GDAP1 ) cause rare subtypes of Charcot–Marie–Tooth disease (CMT2K and CMT4A). CMT2K is an axonal neuropathy while CMT4A is a demyelinating type. In a series of 169 Chinese CMT patients (79 CMT1, 52 CMT2 and 38 unclassified), four unrelated patients (2.37%) were identified with GDAP1 mutations, including two with autosomal recessive CMT2K (AR-CMT2K) and two dominant CMT2K (AD-CMT2K). All patients had disease onset before 5 years of age, and presented with muscle weakness, atrophy, and mild sensory disturbance in distal limbs. Motor nerve conduction velocities of the median nerve were within normal ranges, and compound muscle action potential ranged from 1.5 to 3.8 mV. Sural nerve biopsy revealed loss of large myelinated fibers with regeneration clusters and a few onion bulbs. Electron microscopy showed mitochondrial aggregation in both axons and Schwann cells, and neurofilament accumulation in giant unmyelinated fibers. The p.H256R mutation was found in all patients with GDAP1 compound heterozygous mutations, suggesting that it might be a common mutation in Chinese patients. This study observed no difference in the disease onset, phenotype severity, electrophysiological findings, or pathological changes between AR-CMT2K and AD-CMT2K patients. [ABSTRACT FROM AUTHOR]

Background: Autosomal recessive polycystic kidney disease (ARPKD) constitutes an important cause of pediatric end stage renal disease and is characterized by a broad phenotypic variability. The disease is caused by mutations in a single gene, Polycystic Kidney and Hepatic Disease 1 ( PKHD1), which encodes a large transmembrane protein of poorly understood function called fibrocystin. Based on current knowledge of genotype-phenotype correlations in ARPKD, two truncating mutations are considered to result in a severe phenotype with peri- or neonatal mortality. Infants surviving the neonatal period are expected to carry at least one missense mutation. Case-Diagnosis/Treatment: We report on a female patient with two truncating PKHD1 mutations who survived the first 30 months of life without renal replacement therapy. Our patient carries not only a known stop mutation, c.8011C>T (p.Arg2671*), but also the previously reported c.51A>G PKHD1 sequence variant of unknown significance in exon 2. Using functional in vitro studies we have confirmed the pathogenic nature of c.51A>G, demonstrating activation of a new donor splice site in intron 2 that results in a frameshift mutation and generation of a premature stop codon. Conclusions: This case illustrates the importance of functional mutation analyses and also raises questions regarding the current belief that the presence of at least one missense mutation is necessary for perinatal survival in ARPKD. [ABSTRACT FROM AUTHOR]

Background: Differential diagnosis of prenatally detected hyperechogenic and enlarged kidneys can be challenging as there is a broad phenotypic overlap between several rare genetic and non-genetic disorders. Metabolic diseases are among the rarest underlying disorders, but they demand particular attention as their prognosis and postnatal management differ from those of other diseases. Methods: We report two cases of cystic, hyperechogenic and enlarged kidneys detected on prenatal ultrasound images, resulting in the suspected diagnosis of autosomal recessive polycystic kidney disease (ARPKD). Postnatal clinical course and work-up, however, revealed early, neonatal forms of disorders of fatty acid oxidation (DFAO) in both cases, namely, glutaric acidemia type II, based on identification of the novel, homozygous splice-site mutation c.1117-2A > G in the ETFDH gene, in one case and carnitine palmitoyltransferase II deficiency in the other case. Results: Review of pre- and postnatal sonographic findings resulted in the identification of some important differences that might help to differentiate DFAO from ARPKD. In DFAO, kidneys are enlarged to a milder degree than in ARPKD, and the cysts are located ubiquitously, including also in the cortex and the subcapsular area. Interestingly, recent studies have pointed to a switch in metabolic homeostasis, referred to as the Warburg effect (aerobic glycolysis), as one of the underlying mechanisms of cell proliferation and cyst formation in cystic kidney disease. DFAO are characterized by the inhibition of oxidative phosphorylation, resulting in aerobic glycolysis, and thus they do resemble the Warburg effect. We therefore speculate that this inhibition might be one of the pathomechanisms of renal hyperproliferation and cyst formation in DFAO analogous to the reported findings in ARPKD. Conclusions: Neonatal forms of DFAO can be differentially diagnosed in neonates with cystic or hyperechogenic kidneys and necessitate immediate biochemical work-up to provide early metabolic management. [ABSTRACT FROM AUTHOR]

Background: Constitutional mismatch repair deficiency syndrome results from bi-allelic inheritance of mutations affecting the key DNA mismatch repair genes: MLH1, MSH2, MSH6 or PMS2. Individuals with bi-allelic mutations have a dysfunctional mismatch repair system from birth; as a result, constitutional mismatch repair deficiency syndrome is characterised by early onset malignancies. Fewer than 150 cases have been reported in the literature over the past 20 years. This is the first report of the founder PMS2 mutation - NM_000535.5:c.1500del (p.Val501TrpfsTer94) in exon 11 and its associated cancers in this family. Case presentation: The proband is 30 years old and is alive today. She is of Pakistani ethnic origin and a product of consanguinity. She initially presented aged 24 with painless bleeding per-rectum from colorectal polyps and was referred to clinical genetics. Clinical examination revealed two café-au-lait lesions, lichen planus, and a dermoid cyst. Her sister had been diagnosed in childhood with an aggressive brain tumour followed by colorectal cancer. During follow up, the proband developed 37 colorectal adenomatous polyps, synchronous ovarian and endometrial adenocarcinomas, and ultimately a metachronous gastric adenocarcinoma. DNA sequencing of peripheral lymphocytes revealed a bi-allelic inheritance of the PMS2 mutation NM_000535.5:c.1500del (p.Val501TrpfsTer94) in exon 11. Ovarian tumour tissue demonstrated low microsatellite instability. To date, she has had a total abdominal hysterectomy, bilateral salpingo-oophorectomy, and a total gastrectomy. Aspirin and oestrogen-only hormone replacement therapy provide some chemoprophylaxis and manage postmenopausal symptoms, respectively. An 18-monthly colonoscopy surveillance programme has led to the excision of three high-grade dysplastic colorectal tubular adenomatous polyps. The proband's family pedigree displays multiple relatives with cancers including a likely case of 'true' Turcot syndrome. Conclusions: Constitutional mismatch repair deficiency syndrome should be considered in patients who present with early onset cancer, a strong family history of cancer, and cutaneous features resembling neurofibromatosis type I. Immunohistochemistry analysis of tumour and normal tissue is sensitive and specific for identifying patients with mismatch repair deficiency and should direct DNA sequencing of lymphocytic tissue to establish a diagnosis. Microsatellite instability status appears to be of little value in identifying patients who may have constitutional mismatch repair deficiency syndrome. [ABSTRACT FROM AUTHOR]

Introduction: Type III Bartter syndrome (BS) is an autosomal recessive renal tubule disorder caused by loss-of-function mutations in the CLCNKB gene, which encodes the chloride channel protein ClC-Kb. In this study, we carried out a complete clinical and genetic characterization in a cohort of 30 patients, one of the largest series described. By comparing with other published populations, and considering that 80% of our patients presented the p.Ala204Thr Spanish founder mutation presumably associated with a common phenotype, we aimed to test the hypothesis that allelic differences could explain the wide phenotypic variability observed in patients with type III BS. Methods: Clinical data were retrieved from the referral centers. The exon regions and flanking intronic sequences of the CLCNKB gene were screened for mutations by polymerase chain reaction (PCR) followed by direct Sanger sequencing. Presence of gross deletions or duplications in the region was checked for by MLPA and QMPSF analyses. Results: Polyuria, polydipsia and dehydration were the main common symptoms. Metabolic alkalosis and hypokalemia of renal origin were detected in all patients at diagnosis. Calciuria levels were variable: hypercalciuria was detected in 31% of patients, while 23% had hypocalciuria. Nephrocalcinosis was diagnosed in 20% of the cohort. Two novel CLCNKB mutations were identified: a small homozygous deletion (c.753delG) in one patient and a small deletion (c.1026delC) in another. The latter was present in compound heterozygosis with the already previously described p.Glu442Gly mutation. No phenotypic association was obtained regarding the genotype. Conclusion: A poor correlation was found between a specific type of mutation in the CLCNKB gene and type III BS phenotype. Importantly, two CLCNKB mutations not previously described were found in our cohort. [ABSTRACT FROM AUTHOR]

Background: Mucolipidosis types II and III (ML II/III) are autosomal recessive disorders caused by a deficiency in the lysosomal enzyme N-acetylglucosamine-1-phosphotransferase. We investigated the molecular genetic characteristics of the GNPTAB gene, which codes for the alpha/beta subunits of a phosphotransferase, in Korean ML II/III patients. We included prenatal tests and evaluated the spectrum of mutations in East Asian populations with ML II/III through a literature review.Methods: Seven patients from six families were enrolled in the study including two prenatal tests using chorionic villi samples. A diagnosis of ML II/III was made based on clinical findings and increases in serum lysosomal enzyme levels. PCR and direct sequencing were performed to identify GNPTAB mutations.Results: We found 14 mutant alleles including seven known mutations of c.2189delT (p.Leu730fs*7), c.1090C > T (p.Arg364*), c.2681G > A (p.Trp894*), c.3565C > T (p.Arg1189*), c.310C > T (p.Gln104*), c.1071G > A (p.Trp357*) and c.2574_2575delGA (p.Asn859Glnfs*2). Four were novel variants of unknown significance: c.992A > G (p.Tyr331Cys), c.2666 T > A (p.Leu889*), c.637-6 T > G (p.Thr213Phefs*11), and c.471_472delTT (p.Tyr158Serfs*8). Family studies revealed the probands to be compound heterozygotes. The fetuses carried the same GNPTAB mutations as the mucolipidosis II/III probands in the prenatal diagnosis.Conclusions: We identified GNPTAB mutations in all patients with ML II/III, but did not identify a hot spot in Korean patients. We successfully performed prenatal diagnosis using molecular investigation. [ABSTRACT FROM AUTHOR]

On the Arabian Peninsula, where consanguineous/endogamous marriages are customary, hereditary eye disease is often autosomal recessive and genotype-phenotype correlation is typically straightforward. However, this is not always the case. Lessons I have learned in the course of reconciling genotype with phenotype in the region include the following: (1) although autosomal recessive disease is common, autosomal dominant disease still occurs; (2) an individual or family can be affected by more than one genetic eye disease; and (3) phenotype trumps genotype. [ABSTRACT FROM PUBLISHER]

Autosomal recessive polycystic kidney disease (ARPKD) is a severe monogenic disorder that occurs due to mutations in the PKHD1 gene. Congenital hepatic fibrosis (CHF) associated with ARPKD is characterized by the presence of hepatic cysts derived from dilated bile ducts and a robust, pericystic fibrosis. Cyst growth, due to cyst wall epithelial cell hyperproliferation and fluid secretion, is thought to be the driving force behind disease progression. Liver fibrosis is a wound healing response in which collagen accumulates in the liver due to an imbalance between extracellular matrix synthesis and degradation. Whereas both hyperproliferation and pericystic fibrosis are hallmarks of CHF/ARPKD, whether or not these two processes influence one another remains unclear. Additionally, recent studies demonstrate that inflammation is a common feature of CHF/ARPKD. Therefore, we propose a “pathogenic triumvirate” consisting of hyperproliferation of cyst wall growth, pericystic fibrosis, and inflammation which drives CHF/ARPKD progression. This review will summarize what is known regarding the mechanisms of cyst growth, fibrosis, and inflammation in CHF/ARPKD. Further, we will discuss the potential advantage of identifying a core pathogenic feature in CHF/ARPKD to aid in the development of novel therapeutic approaches. If a core pathogenic feature does not exist, then developing multimodality therapeutic approaches to target each member of the “pathogenic triumvirate” individually may be a better strategy to manage this debilitating disease. [ABSTRACT FROM AUTHOR]

Polycystins 1 and 2, which are mutated in Autosomal Polycystic Kidney Disease, are involved in mechanotransduction through various mechanisms. In renal cells, polycystins not only have an important mechanotransductive role in primary cilia but are also present in intercellular contacts but their role there remains unclear. Here, we address the hypothesis that polycystins are involved in mechanotransduction via intercellular junctions, which would be expected to have consequences on tissue organization. We focused on the role of polycystin 2, which could be involved in mechanical organization at junctions either by its channel activity or by the direct recruitment of cytoskeleton components such as the F-actin cross-linker α-actinin. After mechanical stimulation of intercellular junctions in MDCK renal epithelial cells, α-actinin is rapidly recruited but this is inhibited upon overexpression of PC2 or the D509V mutant that lacks channel activity, and is also decreased upon PC2 silencing. This suggests that a precise dosage of PC2 is necessary for an adequate mechanosensitive α-actinin recruitment at junctions. At the multicellular level, a change in PC2 expression was associated with changes in velocity in confluent epithelia and during wound healing together with a loss of orientation. This study suggests that the mechanosensitive regulation of cytoskeleton by polycystins in intercellular contacts may be important in the context of ADPKD. [ABSTRACT FROM AUTHOR]

Sialidoses are autosomal recessive disorders caused by NEU1 gene mutations and are classified on the basis of their phenotype and onset age. Sialidosis type II, with infantile onset, has a more severe phenotype characterized by coarse facial features, hepatomegaly, dysostosis multiplex, and developmental delay while patients with the late and milder type, known as 'cherry red spot-myoclonus syndrome' develop myoclonic epilepsy, visual impairment and ataxia in the second or third decade of life. The diagnosis is usually suggested by increased urinary bound sialic acid excretion. We recently described genetically diagnosed patients with a specially mild phenotype, no retinal abnormalities and normal urinary sialic acid. This observation suggests that genetic analysis or the demonstration of the neuraminidase enzyme deficiency in cultured fibroblasts are needed to detect and diagnose mildest phenotypes. [ABSTRACT FROM AUTHOR]

Background: Congenital hereditary endothelial dystrophy (CHED) is an autosomal recessive disorder characterized by bilateral, symmetrical, noninflammatory corneal clouding (edema) present at birth or shortly thereafter. This study reports on an unusual delayed presentation of CHED with compound heterozygous SLC4A11 mutations.Materials and Methods: A 45-year-old female, presenting with bilateral decreased vision since childhood that deteriorated in the last 5 years, was evaluated to rule out trauma, viral illness, chemical injury, glaucoma, and corneal endothelial dystrophies. Tear sample was sent for herpes simplex viral (HSV) antigen testing. Genomic DNA from peripheral blood was screened for mutations in all exons of SLC4A11 by direct sequencing. Full-thickness penetrating keratoplasty was done and corneal button was sent for histopathological examination.Results: Slit-lamp findings revealed bilateral diffuse corneal edema and left eye spheroidal degeneration with scarring. Increased corneal thickness (762 μm and 854 μm in the right and left eyes, respectively), normal intraocular pressure (12 mmHg and 16 mmHg in the right and left eyes, respectively), inconclusive confocal scan, and specular microscopy, near normal tear film parameters, were the other clinical features. HSV-polymerase chain reaction was negative. Histopathological examination revealed markedly thickened Descemet's membrane with subepithelial spheroidal degeneration. SLC4A11 screening showed a novel variant p.Ser415Asn, reported mutation p.Cys386Arg and two polymorphisms, all in the heterozygous state and not identified in 100 controls.Conclusions: The study shows, for the first time, compound heterozygous SLC4A11 mutations impair protein function leading to delayed onset of the disease. [ABSTRACT FROM AUTHOR]

Chudley-McCullough syndrome (CMS) is a rare autosomal recessive disorder characterized by sensorineural deafness, agenesis of the corpus callosum, frontal polymicrogyria, interhemispheric cyst, and ventricular enlargement. CMS is caused by mutations in the GPSM2 gene, but until now no more than eight different mutations are on record. We describe two dizygotic twins with a novel homozygous loss-of-function mutation (c.1093C > T; p.Arg365). While one child developed hydrocephalus-prompting shunt implantation immediately after birth, the other sibling did not. The combination of sensorineural hearing loss and partial agenesis of the corpus callosum is a highly recognizable clinico-radiological entity that should prompt mutational analysis of the GPSM2 gene. [ABSTRACT FROM AUTHOR]

Genetic heterogeneity has made the identification of genes related to hearing impairment a challenge. In the absence of a clear phenotypic aetiology, recurrence risk estimates are often based on family segregation and may be imprecise. We profiled by oligonucleotide array- CGH patients presenting non-syndromic hearing loss with presumptive autosomal recessive ( n = 50) or autosomal dominant ( n = 50) patterns of inheritance. Rare copy number variants ( CNVs) were detected in 12 probands; four of the detected CNVs comprised genes previously associated with hearing loss ( POU4F3, EYA4, USH2A, and BCAP31) and were considered causative, stressing the contribution of genomic imbalance to non-syndromic deafness. In six cases, segregation of the CNVs in pedigrees excluded them as causative. In one case, segregation could not be investigated, while in another case, a point mutation likely explains the phenotype. These findings show that the presumptive patterns of inheritance were incorrect in at least two cases, thereby impacting genetic counselling. In addition, we report the first duplication reciprocal to the rare ABCD1, BCAP31, and SLC6A8 contiguous deletion syndrome; as with most microduplication syndromes, the associated phenotype is much milder than the respective microdeletion and, in this case, was restricted to hearing impairment. [ABSTRACT FROM AUTHOR]

Autosomal recessive polycystic kidney disease (ARPKD) is usually detected late in pregnancies in embryos with large echogenic kidneys accompanied by oligohydramnios. Hundreds of private pathogenic variants have been identified in the large PKHD1 gene in various populations. Yet, because of the large size of the gene, segregation analysis of microsatellite polymorphic markers residing in the PKDH1 locus has commonly been utilized for prenatal diagnosis. Keeping in mind the limitations of this strategy, we utilized it for testing 7 families with affected fetuses or newborns, of which in 5 at least one parent was Ashkenazi, and identified that the same haplotype was shared by the majority of the Ashkenazi parents (7/9). This led us to suspect that they carry the same founder mutation. Whole Exome analysis of DNA from a fetus of one of the families detected an already known pathogenic variant c.3761_3762delCCinsG, an indel variant resulting in frameshift (p.Ala1254GlyfsX49). This variant was detected in 9 parents (5 families), of them 7 individuals were Ashkenazi and one Moroccan Jew who shared the same haplotype, and one Ashkenazi, who carried the same variant on a recombinant haplotype. Screening for this variant in 364 Ashkenazi individuals detected 2 carriers. These findings suggest that although c.3761_3762delCCinsG is considered one of the frequent variants detected in unrelated individuals, and was thought to have occurred independently on various haplotypes, it is in fact a founder mutation in the Ashkenazi population. [ABSTRACT FROM AUTHOR]

Background: Hepatorenal fibrocystic diseases (HRFCDs) are a group of monogenic disorders characterized by developmental abnormalities involving the liver and kidney. In this study, we performed genotype and phenotype analyses of children with HRFCDs to determine the distribution of underlying diseases. Methods: A total of 36 children with HRFCDs were recruited, with genetic tests being performed in 22 patients and 14 patients diagnosed clinically as having autosomal recessive polycystic kidney disease (ARPKD). Results: In children with HRFCDs, ARPKD was the most common disease, found in 16/36 (44.4 %), followed by nephronophthisis 13 (NPHP13) in 11/36 (30.6 %) and Meckel-Gruber syndrome type 3 (MKS3) in 4/36 (11.1 %). Renal function deteriorated faster in children with NPHP13. The main hepatic pathology was Caroli disease in the NPHP13 patients, while most other patients had Caroli syndrome or congenital hepatic fibrosis. Of note, three of four MKS3 patients had an accompanying choledochal cyst. No ARPKD patient had other organ involvement, while several NPHP13 patients had ocular and/or neurodevelopmental involvement. In contrast, all MKS3 patients had severe ocular and neurodevelopmental involvement. Conclusions: NPHP13 is a major disease in the HRFCD category, and thorough evaluation of its clinical features, including kidney, liver and other organ involvement, may aid in the differential diagnosis of HRFCD. [ABSTRACT FROM AUTHOR]

The autosomal recessive cerebellar ataxias (ARCA) affect both the central and the peripheral nervous systems. They are also characterized by a relatively high level of genetic heterogeneity with well over 40 genes already implicated. The present study aimed to identify the gene mutation responsible for a complex phenotype comprising cerebellar ataxia and intellectual disability segregating in an Omani consanguineous family. Homozygosity-guided exome data analysis identified a novel frameshift mutation (c.2319_2322del) within the sorting nexin 14 gene (SNX14), which predicts complete absence of the SNX14 encoded protein. Segregation within the family of the sequence variation is consistent with its pathogenic role. Importantly, loss-of-function mutations in SNX14 have recently been described as a cause of a clinically distinguishable recessive syndrome consisting of cerebellar atrophy, ataxia, coarsened facial features, and intellectual disability. This study expands the genetic diversity of ataxia genes in the Omani population and have important implications for the clinical and molecular diagnosis of this condition in affected individuals. [ABSTRACT FROM AUTHOR]

Berardinelli-Seip congenital lipodystrophy (BSCL) is an autosomal recessive disorder, characterized by the generalized absence of subcutaneous fat and muscular hypertrophy. Meanwhile other signs and symptoms have already been reported with this genetic disorder. Herein, we report an infant with BSCL, who was referred to our center because of acromegaloid and muscular appearance from the age of three months. He had dark skin, hypertrichosis prominent subcutaneous vessels and organomegaly in physical examination. Genetic study showed novel homozygous mutations in the AGPAT2 gene, which confirmed diagnosis of BSCL in this patient. Although clinical suspicious could help us to make diagnosis of congenital disorders, definite diagnosis relies on genetic studies. [ABSTRACT FROM AUTHOR]

Background: Autosomal recessive polycystic kidney disease (ARPKD) is an early-onset form of polycystic kidney disease that often leads to devastating outcomes for patients. ARPKD is caused by mutations in the PKHD1 gene, an extensive gene that encodes for the ciliary protein fibrocystin/polyductin. Next-generation sequencing is presently the best option for molecular diagnosis of ARPKD. Our aim was to set up the first study of ARPKD patients from the Czech Republic, to determine the composition of their mutations and genotype-phenotype correlations, along with establishment of next-generation sequencing of the PKHD1 gene that could be used for the diagnosis of ARPKD patients. Methods: Mutational analysis of the PKHD1 gene was performed in 24 families using the amplicon-based nextgeneration sequencing (NGS) technique. In patients without 2 causal mutations identified by NGS, subsequent MLPA analysis of the PKHD1 gene was carried out. Results: Two underlying mutations were detected in 54 % of families (n = 13), one mutation in 13 % of families (n = 3), and in 33 % of families (n=8) no mutation could be detected. Overall, seventeen different mutations (5 novel) were detected, including deletion of one exon. The detection rate in our study reached 60 % in the entire cohort of patients; but 90 % in the group of patients who fulfilled all clinical criteria of ARPKD, and 42 % in the group of patients with unknown kidney pathology. The most frequent mutation was T36M, accounting for nearly 21 % of all identified mutations. Conclusions: Next-generation sequencing of the PKHD1 gene is a very useful method of molecular diagnosis in patients with a full clinical picture of ARPKD, and it has a high detection rate. Furthermore, its relatively low costs and rapidity allow the molecular genetic analysis of patients without the full clinical criteria of ARPKD, who might also have mutations in the PKHD1 gene. [ABSTRACT FROM AUTHOR]

Familial multiple intestinal atresias is an autosomal recessive disease with or without combined immunodeficiency. In the last year, several reports have described mutations in the gene TTC7A as causal to the disease in different populations. However, exact correlation between different genotypes and various phenotypes are not clear. In this study, we report identification of novel compound heterozygous mutations in TTC7A gene in a Malay girl with familial multiple intestinal atresias and severe combined immunodeficiency ( MIA-SCID) by whole exome sequencing. We found two mutations in TTC7A: one that destroyed a putative splicing acceptor at the junction of intron 17/exon 18 and one that introduced a stop codon that would truncate the last two amino acids of the encoded protein. Reviewing the recent reports on TTC7A mutations reveals correlation between the position and nature of the mutations with patient survival and clinical manifestations. Examination of public databases also suggests carrier status for healthy individuals, making a case for population screening on this gene, especially in populations with suspected frequent founder mutations. [ABSTRACT FROM AUTHOR]

Autosomal recessive polycystic kidney disease is among the most common inherited ciliopathies and is caused by mutations in the polycystic kidney and hepatic disease 1 (PKHD1) gene. Despite its great phenotypic variability, this condition is usually diagnosed during the neonatal and early infantile periods. We report a 37+3-gestational- week neonate presenting with fatal autosomal recessive polycystic kidney disease who died at 28 hours of life from severe respiratory failure. The familial history is significant because a previous sibling died in utero at 24+2 weeks of gestational age and was diagnosed with polycystic kidney disease based on prenatal ultrasonography and autopsy. Our patient's autopsy revealed findings compatible with polycystic kidney disease. In addition, a PKHD1 gene study of peripheral blood leukocytes identified the compound heterozygote mutation c.274C>T(p.Arg92Trp), as well as the novel heterozygous nonsense mutation c.2770C>T(p.Gln924*). [ABSTRACT FROM AUTHOR]

Background: In the present study, we report on a couple who underwent prenatal genetic diagnosis for autosomal recessive polycystic kidney disease (ARPKD). Case presentation: This healthy couple had previously had a healthy boy but had experienced two consecutive neonatal deaths due to respiratory distress resulting from pulmonary hypoplasia caused by oligohydramnios. The woman consulted our facility after she realized she was pregnant again. We promptly performed a carrier test for the PKHD1 gene by target exome sequencing of samples from the couple. A pathogenic mutation was identified only in the paternal allele (c.9008C>T, p.S3003F). The mutation was confirmed by Sanger sequencing of the DNA from formalin-fixed, paraffin-embedded, kidney tissue of the second neonate patient and was not found in the healthy sibling. We then performed haplotype analyses using microsatellite markers scattered throughout the PKHD1 gene. DNA from the amniocentesis was determined to belong to a carrier, and the couple decided to continue with the pregnancy, obtaining a healthy newborn. Subsequent detailed examination of the exome data suggested higher read depth at exons 45 and 46. Multiplex ligation-dependent probe amplification allowed identification of duplication of these two exons. This case suggests the potential usefulness of target exome sequencing in the prenatal diagnosis of the PKHD1 gene in ARPKD. Conclusions: This is the first report of intragenic duplication in the PKHD1 gene in ARPKD. [ABSTRACT FROM AUTHOR]

Charcot–Marie–Tooth disease is a group of genetically heterogeneous disorders characterized by a sensorimotor polyneuropathy with subsequent muscle atrophy, areflexia, and sensory loss. More than 60 genes have been linked to Charcot–Marie–Tooth phenotypes, including IGHMBP2 . Until recently, mutations in IGHMBP2 were exclusively associated with spinal muscular atrophy with respiratory distress (SMARD1). We present a sibling pair with a novel homozygous truncating mutation in IGHMBP2 . The patients presented with childhood-onset distal weakness, wasting in the upper and lower limbs, areflexia and decreased sensation, but no respiratory involvement. Exome sequencing was performed and a homozygous variant was identified (c.2601_2604del; p.Lys868Profs*109). Sanger sequencing confirmed the presence of this variant in a homozygous state in the two affected siblings, while both parents were heterozygous. Further analyses showed decreased mRNA and IGHMBP2 protein in a lymphoblast cell line derived from one of the siblings. We demonstrate the utility of next-generation sequencing in reaching a molecular diagnosis for a heterogeneous condition such as Charcot–Marie–Tooth. Taken together, our data and that from the literature suggest that the spectrum of clinical presentations associated with mutations in IGHMBP2 may be secondary, at least in part, to the amount of residual protein. [ABSTRACT FROM AUTHOR]

Background: Neonatal autosomal-recessive polycystic kidney disease (ARPKD) is associated with pulmonary hypoplasia and severe respiratory distress. There is no published information on long-term lung function in ARPKD survivors.Methods: Pulmonary function tests, including spirometry and diffusion capacity, were performed in a nationwide cohort of Finnish paediatric patients with ARPKD. The annual incidence of respiratory infections and the need for permanent asthma medication were also evaluated in this population.Results: Pulmonary function in 11 children surviving the neonatal period was good when measured after a median follow-up time of 10.4 years (range 5.4-16.1 years). None of the patients required oxygen supplementation, and only one patient had asthma. Patients who had received ventilator therapy during infancy had significantly lower maximal instantaneous forced expiratory flow (MEF%) (66%; 43-93% vs 105%; 63-110%; p=0.048) and forced expiratory volume/forced vital capacity (0.76; 0.7-0.81 vs 0.89; 0.77-0.91; p=0.03) than patients without a history of mechanical ventilation, suggesting tendency for airway obstruction in the former group of patients. The frequency of respiratory infections did not differ from Finnish paediatric population in general.Conclusions: The results of pulmonary function tests were within reference values for most patients with ARPKD, which suggested good long-term lung prognosis. Lung function tests should be considered for patients with ARPKD with a history of mechanical ventilation during infancy. [ABSTRACT FROM AUTHOR]

MYH9-related disease ( MYH9- RD) is a rare autosomal dominant disease caused by mutation of MYH9, the gene encoding for the heavy chain of non-muscle myosin IIA ( NMMHC-IIA). MYH9- RD patients have macrothrombocytopenia and granulocyte inclusions (pathognomonic sign of the disease) containing wild-type and mutant NMMHC-IIA. During life they might develop sensorineural hearing loss, cataract, glomerulonephritis, and elevation of liver enzymes. One of the MYH9 mutations, p. R705H, was previously reported to be associated with DFNA17, an autosomal dominant non-syndromic sensorineural hearing loss without any other features associated. We identified the same mutation in two unrelated families, whose four affected individuals had not only hearing impairment but also thrombocytopenia, giant platelets, leukocyte inclusions, as well as mild to moderate elevation of some liver enzymes. Our data suggest that DFNA17 should not be a separate genetic entity but part of the wide phenotypic spectrum of MYH9- RD characterized by congenital hematological manifestations and variable penetrance and expressivity of the extra-hematological features. [ABSTRACT FROM AUTHOR]

Background: Oculocutaneous albinism (OCA) is an autosomal recessive disorder. The most common type OCA1 and OCA2 are caused by homozygous or compound heterozygous mutations in the tyrosinase gene (TYR) and OCA2 gene, respectively. Objective: The purpose of this study was to evaluate the molecular basis of oculocutaneous albinism in four Chinese families. Patients and Methods: Four non-consanguineous OCA families were included in the study. The TYR and OCA2 genes of all individuals were amplified by polymerase chain reaction (PCR), sequenced and compared with a reference database. Results: Four patients with a diagnosis of oculocutaneous albinism, presented with milky skin, white or light brown hair and nystagmus. Genetic analyses demonstrated that patient A was compound heterozygous for c.1037-7T.A, c.1037-10_11delTT and c.1114delG mutations in the TYR gene; patient B was heterozygous for c.593C>T and c.1426A>G mutations in the OCA2 gene, patients C and D were compound heterozygous mutations in the TYR gene (c.549_550delGT and c.896G>A, c.832C>T and c.985T>C, respectively). The heterozygous c.549_550delGT and c.1114delG alleles in the TYR gene were two novel mutations. Interestingly, heterozygous members in these pedigrees who carried c.1114delG mutations in the TYR gene or c.1426A>G mutations in the OCA2 gene presented with blond or brown hair and pale skin, but no ocular disorders when they were born; the skin of these patients accumulated pigment over time and with sun exposure. Conclusion: This study expands the mutation spectrum of oculocutaneous albinism. It is the first time, to the best of our knowledge, to report that c.549_550delGT and c.1114delG mutations in the TYR gene were associated with OCA. The two mutations (c.1114delG in the TYR gene and c.1426A>G in the OCA2 gene) may be responsible for partial clinical manifestations of OCA. [ABSTRACT FROM AUTHOR]

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous, autosomal recessive disorder that results from functional and ultrastructural abnormalities of motile cilia. Patients with PCD have diverse clinical phenotypes that include chronic upper and lower respiratory tract infections, situs inversus, heterotaxy with or without congenital heart disease, and male infertility, among others. In this report, the carrier frequencies for eleven mutations in eight PCD-associated genes (DNAI1, DNAI2, DNAH5, DNAH11, CCDC114, CCDC40, CCDC65, and C21orf59) that had been found in individuals of Ashkenazi Jewish descent were investigated in order to advise on including them in existing clinical mutation panels for this population. Results showed relatively high carrier frequencies for the DNAH5 c.7502G>C mutation (0.58%), the DNAI2 c.1304G>A mutation (0.50%), and the C21orf59 c.735C>G mutation (0.48%), as well as lower frequencies for mutations in DNAI1, CCDC65, CCDC114, and DNAH11 (0.10- 0.29%). These results suggest that several of these genes should be considered for inclusion in carrier screening panels in the Ashkenazi Jewish population. [ABSTRACT FROM AUTHOR]