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Background: Counseling for whole-exome sequencing (WES) could benefit from aligning parents' pre- and post-disclosure attitudes. A few studies have qualitatively compared parents' pre- and post-disclosure attitudes toward receiving WES results for their child in a diagnostic setting. This study explored these attitudes in the context of children with a developmental delay., Methods: Semi-structured interviews were conducted with parents (n = 27) of 16 children undergoing diagnostic WES in trio-analysis, both before and after receiving results., Results: Three key insights emerged. First, the distinction between hoping and expecting was relevant for shaping parents' experiences with receiving results related to the primary indication. Second, parents of young children whose development of autonomous capacities was uncertain sometimes found themselves in a situation resembling a Catch-22 when confronted with decisions about unsolicited findings (UFs): an important reason for consenting to WES was to gain a better picture of how the child might develop, but in order to make responsible choices about UFs, some ideas of their child's development is needed. Third, default opt-ins and opt-outs helped parents fathom new kinds of considerations for accepting or declining UFs in different categories, thereby aiding decision-making., Conclusion: Results from this study are relevant for counseling and policy development., (© 2023 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.)

Background: Massively parallel sequencing techniques, such as whole exome sequencing (WES) and whole genome sequencing (WGS), may reveal unsolicited findings (UFs) unrelated to the diagnostic aim. Such techniques are frequently used for diagnostic purposes in pediatric cases of developmental delay (DD). Yet policy guidelines for informed consent and return of UFs are not well equipped to address specific moral challenges that may arise in these children's situations., Discussion: In previous empirical studies conducted by our research group, we found that it is sometimes uncertain how children with a DD will develop and whether they could come to possess capacities for autonomous decision-making in the future. Parents sometimes felt this brought them into a Catch-22 like situation when confronted with choices about UFs before undergoing WES in trio-analysis (both the parents' and child's DNA are sequenced). An important reason for choosing to consent to WES was to gain more insight into how their child might develop. However, to make responsible choices about receiving or declining knowledge of UFs, some idea of their child's future development of autonomous capacities is needed. This undesirable Catch-22 situation was created by the specific policy configuration in which parents were required to make choices about UFs before being sequencing (trio-analysis). We argue that this finding is relevant for reconfiguring current policies for return of UFs for WES/WGS and propose guidelines that encompass two features. First, the informed consent process ought to be staged. Second, differing guidelines are required for withholding/disclosing a UF in cases of DD appropriate to the level of confidence there is about the child's future developmental of autonomous capacities., Conclusion: When combined with a dynamic consent procedure, these two features of our guidelines could help overcome significant moral challenges that present themselves in the situations of children undergoing genomic sequencing for clarifying a DD., (© 2023. The Author(s).)

Whole-genome sequencing (WGS) can provide valuable health insight for research participants or patients. Opportunities to be sequenced are increasing as direct-to-consumer (DTC) testing becomes more prevalent, but it is still fairly unusual to have been sequenced. We offered WGS to fourteen professionals with pre-existing familiarity with an interest in human genetics - healthcare, science, policy and art. Participants received a hard drive containing their personal sequence data files (.BAM,.gvcf), without further explanation or obligation, to consider how experiencing WGS firsthand might influence their professional attitudes. We performed semi-structured pre- and post-sequencing interviews with each participant to identify key themes that they raised after being sequenced. To evaluate how their experience of the procedure evolved over time, we also conducted a questionnaire to gather their views 3 years after receiving their genomic data. Participants were generally satisfied with the experience (all 14 participants would choose to participate again). They mostly decided to participate out of curiosity (personal) and to learn from the experience (professional). Whereas most participants slightly developed their original perspective on genetic data, a small selection of them radically changed their views over the course of the project. We conclude that personal experience of sequencing provides an interesting alternative perspective for experts involved in leading, planning, implementing or researching genome sequencing services. Moreover, the personal experience may provide professionals with a better understanding of the challenges visitors of the Genetics Clinic of the Future may face., (© 2022. The Author(s).)

The overall diagnostic yield of massively parallel sequencing-based tests in patients with chronic kidney disease (CKD) is 30% for paediatric cases and 6-30% for adult cases. These figures should encourage nephrologists to frequently use genetic testing as a diagnostic means for their patients. However, in reality, several barriers appear to hinder the implementation of massively parallel sequencing-based diagnostics in routine clinical practice. In this article we aim to support the nephrologist to overcome these barriers. After a detailed discussion of the general items that are important to genetic testing in nephrology, namely genetic testing modalities and their indications, clinical information needed for high-quality interpretation of genetic tests, the clinical benefit of genetic testing and genetic counselling, we describe each of these items more specifically for the different groups of genetic kidney diseases and for CKD of unknown origin., (© The Author(s) 2021. Published by Oxford University Press on behalf of the ERA.)

In a previous study we found that parents of children with developmental delay (DD) favoured acceptance of unsolicited findings (UFs) for medically actionable conditions in childhood, but that preferences diverged for UFs with no medical actionability, or only in adulthood, and regarding carrier status. Sometimes the child's future autonomy formed a reason for withholding UFs for the present, despite an unfavourable prognosis concerning the child's cognitive capabilities. This might be different for children undergoing whole exome sequencing (WES) for reasons other than DD and who are expected to exert future autonomy. This is the focus of the current study. We conducted nine qualitative, semi-structured interviews with parents of children, ages <1-15, after consenting to WES, but prior to feedback of results, and with three adolescent children. Several parents wished to receive any information that might in whatever way be relevant to the health and well-being of their child, and to a lesser extent wished the inclusion of information about non-actionable disorders and information concerning carrier status of autosomal recessive disorders. Although parents understood the rationale behind the centre's UFs disclosure policy, they also felt that they needed this information in order to be able to exert their parental responsibility and take good care of a child still dependent on them. Parents reason from their notion of parental responsibility but are also inclined to take adolescent children's preferences seriously and acknowledge the child's incipient autonomy as a ground for granting an increasing degree of self-determination on the road to adulthood.

We performed a large outcome study at group and individual level in which the goals of genetic counselling were operationalized into cognitive and affective outcomes: empowerment, perceived personal control and anxiety. We then examined which socio-demographic and clinical variables were associated with changes in these outcomes. Data came from 1479 counselees who completed questionnaires (GCOS-18, PPC and STAI) at three time points: before the start of genetic counselling, after the first consultation and after the results of genetic counselling were disclosed. Results showed that at group level empowerment, perceived personal control and anxiety improved significantly after the whole genetic counselling process. Effect-sizes were medium for empowerment and small for the other outcomes. At individual level, 48% of counselees improved in empowerment, 21% in perceived personal control and 17% in anxiety. Around 10% of counselees worsened on all outcomes. Only 'reason for referral' and 'genetic test result' were significantly associated with changes in outcomes. This study demonstrated improvements among counselees in cognitive and affective outcomes after genetic counselling at group level. However, our results also suggest that there are opportunities for improvement at individual level, as many counselees remained stable and some even worsened on all outcomes. Routine outcome monitoring could help to explore the needs of counselees and could help to identify counselees who worsen.

RNA polymerase III (Pol III) is an essential 17-subunit complex responsible for the transcription of small housekeeping RNAs such as transfer RNAs and 5S ribosomal RNA. Biallelic variants in four genes (POLR3A, POLR3B, and POLR1C and POLR3K) encoding Pol III subunits have previously been found in individuals with (neuro-) developmental disorders. In this report, we describe three individuals with biallelic variants in POLR3GL, a gene encoding a Pol III subunit that has not been associated with disease before. Using whole exome sequencing in a monozygotic twin and an unrelated individual, we detected homozygous and compound heterozygous POLR3GL splice acceptor site variants. RNA sequencing confirmed the loss of full-length POLR3GL RNA transcripts in blood samples of the individuals. The phenotypes of the described individuals are mainly characterized by axial endosteal hyperostosis, oligodontia, short stature, and mild facial dysmorphisms. These features largely fit within the spectrum of phenotypes caused by previously described biallelic variants in POLR3A, POLR3B, POLR1C, and POLR3K. These findings further expand the spectrum of POLR3-related disorders and implicate that POLR3GL should be included in genetic testing if such disorders are suspected.

Background: Steroid-sensitive nephrotic syndrome (SSNS), the most common form of nephrotic syndrome in childhood, is considered an autoimmune disease with an established classic HLA association. However, the precise etiology of the disease is unclear. In other autoimmune diseases, the identification of loci outside the classic HLA region by genome-wide association studies (GWAS) has provided critical insights into disease pathogenesis. Previously conducted GWAS of SSNS have not identified non-HLA loci achieving genome-wide significance., Methods: In an attempt to identify additional loci associated with SSNS, we conducted a GWAS of a large cohort of European ancestry comprising 422 ethnically homogeneous pediatric patients and 5642 ethnically matched controls., Results: The GWAS found three loci that achieved genome-wide significance, which explain approximately 14% of the genetic risk for SSNS. It confirmed the previously reported association with the HLA-DR/DQ region (lead single-nucleotide polymorphism [SNP] rs9273542, P =1.59×10 -43 ; odds ratio [OR], 3.39; 95% confidence interval [95% CI], 2.86 to 4.03) and identified two additional loci outside the HLA region on chromosomes 4q13.3 and 6q22.1. The latter contains the calcium homeostasis modulator family member 6 gene CALHM6 (previously called FAM26F ). CALHM6 is implicated in immune response modulation; the lead SNP (rs2637678, P =1.27×10 -17 ; OR, 0.51; 95% CI, 0.44 to 0.60) exhibits strong expression quantitative trait loci effects, the risk allele being associated with lower lymphocytic expression of CALHM6 ., Conclusions: Because CALHM6 is implicated in regulating the immune response to infection, this may provide an explanation for the typical triggering of SSNS onset by infections. Our results suggest that a genetically conferred risk of immune dysregulation may be a key component in the pathogenesis of SSNS., (Copyright © 2019 by the American Society of Nephrology.)

Patient empowerment has been identified as a key outcome goal in genetic counselling, and a patient reported outcome measure (PROM) has been developed to measure empowerment in genetic services: the Genetic Counselling Outcome Scale (GCOS). Here we validate the GCOS for a large and diverse Dutch study sample of 2194 patients referred to two clinical genetic centres for counselling about a wide range of conditions (heart disease, neurological disorders, cancer, congenital syndromes, intellectual disability and prenatal pathology). Our results suggest that the GCOS consists of a hierarchical 6-factor structure, with a main scale for empowerment and six subscales: uncertainty about heredity, hope, negative emotions, knowledge about the condition, knowledge about genetic services and uncertainty about the treatment. Six of the original 24 GCOS items were removed due to low factor loadings and small inter-item correlations. Internal consistency and test-retest reliability of the main scale and most subscales were satisfactory. Convergent validity was confirmed by moderate positive and moderate/strong negative associations between the GCOS main scale and other validated outcome measures. Responsiveness was comparable to that of other validated outcome measures. We saw significant improvement in the GCOS main scale and all the subscales after the first genetic counselling session. This study contributes to the international validation process of the GCOS, with the ultimate goal of using this instrument as a PROM, with empowerment as an outcome measure, to evaluate and improve the quality of genetic counselling in various clinical genetics settings.

A mutation in GDF6 was recently found to underlie a multiple synostoses syndrome. In this report, we describe the second family with GDF6-related multiple synostoses syndrome (SYNS4), caused by a novel c.1287C>A/p.Ser429Arg mutation in GDF6. In addition to synostoses of carpal and/or tarsal bones, at least 6 of 10 affected patients in this family have been diagnosed with mild to moderate hearing loss. In four of them otosclerosis was said to be present, one patient had hearing loss due to severe stapes fixation at the age of 6 years, providing evidence that hearing loss in the GDF6-related multiple synostoses syndrome can be present in childhood. Two others had surgery for stapes fixation at adult age. We hypothesize that, identical to the recently published GDF6-related multiple synostoses family, the p.Ser429Arg mutation also leads to a gain of function. The previously reported c.1330T>A/pTyr444Asn mutation was located in a predicted Noggin and receptor I interacting domain and the gain of function was partly due to resistance of the mutant GDF6 to the BMP-inhibitor Noggin. The results in our family show that mutations predicting to affect the type II receptor interface can lead to a similar phenotype and that otosclerosis presenting in childhood can be part of the GDF6-related multiple synostoses syndrome., (© 2017 Wiley Periodicals, Inc.)

Mutations in SCN2A, a gene encoding the voltage-gated sodium channel Nav1.2, have been associated with a spectrum of epilepsies and neurodevelopmental disorders. Here, we report the phenotypes of 71 patients and review 130 previously reported patients. We found that (i) encephalopathies with infantile/childhood onset epilepsies (≥3 months of age) occur almost as often as those with an early infantile onset (<3 months), and are thus more frequent than previously reported; (ii) distinct phenotypes can be seen within the late onset group, including myoclonic-atonic epilepsy (two patients), Lennox-Gastaut not emerging from West syndrome (two patients), and focal epilepsies with an electrical status epilepticus during slow sleep-like EEG pattern (six patients); and (iii) West syndrome constitutes a common phenotype with a major recurring mutation (p.Arg853Gln: two new and four previously reported children). Other known phenotypes include Ohtahara syndrome, epilepsy of infancy with migrating focal seizures, and intellectual disability or autism without epilepsy. To assess the response to antiepileptic therapy, we retrospectively reviewed the treatment regimen and the course of the epilepsy in 66 patients for which well-documented medical information was available. We find that the use of sodium channel blockers was often associated with clinically relevant seizure reduction or seizure freedom in children with early infantile epilepsies (<3 months), whereas other antiepileptic drugs were less effective. In contrast, sodium channel blockers were rarely effective in epilepsies with later onset (≥3 months) and sometimes induced seizure worsening. Regarding the genetic findings, truncating mutations were exclusively seen in patients with late onset epilepsies and lack of response to sodium channel blockers. Functional characterization of four selected missense mutations using whole cell patch-clamping in tsA201 cells-together with data from the literature-suggest that mutations associated with early infantile epilepsy result in increased sodium channel activity with gain-of-function, characterized by slowing of fast inactivation, acceleration of its recovery or increased persistent sodium current. Further, a good response to sodium channel blockers clinically was found to be associated with a relatively small gain-of-function. In contrast, mutations in patients with late-onset forms and an insufficient response to sodium channel blockers were associated with loss-of-function effects, including a depolarizing shift of voltage-dependent activation or a hyperpolarizing shift of channel availability (steady-state inactivation). Our clinical and experimental data suggest a correlation between age at disease onset, response to sodium channel blockers and the functional properties of mutations in children with SCN2A-related epilepsy., (© The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Objective: To detect determinants for photoparoxysmal EEG response (PPR) in SCN1A-related Dravet syndrome (DS)., Methods: Data were studied from nationwide medical histories and EEGs of DS-patients (n=53; 31 males, age 2-19years). Detailed questionnaires on visual stimuli were completed by parents (n=49)., Results: PPR was found in 22 patients (42%; median age 1.25yr), and repeatedly in 17%. PPR (17% of 249 intermittent photic stimulation (IPS)-EEGs) occurred more often with optimal IPS protocols (OR 2.11 [95%CI 1.09-4.13]) and in EEGs showing spontaneous epileptiform abnormalities (OR 5.08 [95%CI 2.05-12.55]). PPR-positive patients tended to be younger at first (p=0.072) and second seizure (p=0.049), showed severe intellectual disability (p=0.042), and had more often spontaneous occipital epileptiform abnormalities (p<0.001). Clinical sensitivity was reported in medical files in 22% of patients and by parents in 43% (self-induction 24%). Clinical or EEG proven visual sensitivity was detected in 65% of cases., Conclusions: Sensitivity to visual stimuli is very common in DS and more often noticed by parents than confirmed by EEG. Detection of PPR improves with repetitive tests using accurate IPS protocols., Significance: Photosensitivity is an important feature in DS and seems to be a marker of the severity of the disorder. Therefore repeated standardized IPS should be encouraged., (Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Parents' preferences for unsolicited findings (UFs) from diagnostic whole-exome sequencing (WES) for their children remain largely unexplored. Our aim was to gain insight into parental considerations favoring acceptance/decline of UFs pertaining to their child. We conducted 20 qualitative, semistructured interviews with parents (n=34) of children with a developmental delay, aged <1 to 17 years, after consenting to WES, but before feedback of results. Key findings from our study were that all parents favored acceptance of UFs for medically actionable conditions in childhood, but that preferences and considerations diverged for UFs with no medical actionability, or only in adulthood, and regarding carrier-status. Sometimes non-medical utility considerations (considerations of usefulness of knowing UFs, not rooted in (preventive) medical treatment or controls) were given in favor of disclosure of UFs. Sometimes the child's future autonomy formed a reason to withhold UFs at present, despite an unfavorable prognosis concerning the child's cognitive capabilities. Some parents only preferred receiving UFs if these findings were directly related to their reasons for seeking a diagnosis. These findings are essential for developing morally responsible policy and for counseling. Further research should focus on whether considerations of non-medical utility alone can justify disclosure of UFs and whether reasons for seeking a diagnosis place further constraints on what UFs may be returned/withheld. How parents can be aided in contemplating different scenarios regarding their child's future development also deserves further inquiry.

Background: Our clinical observations and two earlier studies indicate familial clustering to be involved in chronic chilblains. Demonstrating phenotypic familial aggregation is a next step to investigate the origin of familial clustering., Objective: This study was initiated to assess evidence for phenotypic familial aggregation in chronic chilblains., Methods: Using a case-control family design in a primary care setting, we computed the familial relative risk of at least one episode of chronic chilblains during life with 95% confidence intervals (CIs). The study population consisted of 192 relatives of 31 case probands (at least one confirmed episode of chronic chilblains). The control population consisted of 178 relatives of 31 sex- and age-matched index controls (no history of chronic chilblains)., Results: The familial relative risk of chronic chilblains was 3.6 (95% CI 1.9-7.3). Additional sensitivity analysis shows similar figures., Conclusion: We demonstrate robust phenotypic familial aggregation in chronic chilblains., (© The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Proximal duplications of chromosome 1q are rare chromosomal abnormalities. Most patients with this condition present with neurological, urogenital, and congenital heart disease and short life expectancy. Mosaicism for trisomy 1q10q23.3 has only been reported once in the literature. Here we discuss a second case: a girl with a postnatal diagnosis of a de novo pure mosaic trisomy 1q1023.3 who has no urogenital or cardiac anomalies.

Objectives: This study aimed to describe seizure precipitants in Dravet syndrome (DS) compared with other epilepsies., Methods: Seizure precipitants as reported in a Dutch cohort of patients with DS with pathogenic SCN1A mutations (n=71) were compared with those of a cohort with childhood epilepsy (n=149) and of a community-based cohort with epilepsy (n=248); for all three Dutch cohorts, the same type of questionnaire was used. Seizure precipitants were categorized as 'fever', 'visual stimuli', 'sleep deprivation', 'stress, including physical exercise', 'auditory stimuli', and 'other'., Results: For 70 (99%) of 71 patients with DS, at least one seizure precipitant was recalled by parents. Seizure precipitants that were reported in more than half of the cohort with DS were as follows: having a fever (97%), having a cold (68%), taking a bath (61%), having acute moments of stress (58%), and engaging in physical exercise (56%). Seizure precipitants freely recalled by parents were often related to ambient warmth or cold-warmth shifts (41%) and to various visual stimuli (18%). Patients with DS had more positive seizure precipitant categories (median 4) compared with the cohort with childhood epilepsy (median 2) and the community-based cohort with epilepsy (median 0) (p<0.001) and showed the highest percentage in each category (all p<0.001). Within the category 'stress, including physical exercise', physical exercise was more often reported to provoke seizures in stress-sensitive patients in the cohort with DS than in the cohort with childhood epilepsy (78% vs. 35%, p<0.001). In the cohort with childhood epilepsy, physical exercise was more often reported in fever-sensitive children than in other children (25% vs. 12%, p=0.042)., Conclusions: Our study shows a high prevalence of a range of seizure precipitants in DS. Our results underscore elevated body temperature as an important seizure precipitant, whether caused by fever, warm bath, ambient warmth, or physical exercise. Knowledge of these seizure precipitants may improve preventive strategies in the otherwise difficult treatment of DS., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background/aims: Mutations in the inwardly-rectifying K(+)-channel KCNJ10/Kir4.1 cause autosomal recessive EAST syndrome (epilepsy, ataxia, sensorineural deafness and tubulopathy). KCNJ10 is expressed in the distal convoluted tubule of the kidney, stria vascularis of the inner ear and brain glial cells. Patients diagnosed clinically with EAST syndrome were genotyped and mutations in KCNJ10 were studied functionally., Methods: Patient DNA was amplified and sequenced, and new mutations were identified. Mutant and wild-type KCNJ10 constructs were cloned and heterologously expressed in Xenopus oocytes. Whole-cell K(+) currents were measured by 2-electrode voltage clamping and channel expression was analysed by Western blotting., Results: We identified 3 homozygous mutations in KCNJ10 (p.F75C, p.A167V and p.V91fs197X), with mutation p.A167V previously reported in a compound heterozygous state. Oocytes expressing wild-type human KCNJ10 showed inwardly rectified currents, which were significantly reduced in all of the mutants (p < 0.001). Specific inhibition of KCNJ10 currents by Ba(2+) demonstrated a large residual function in p.A167V only, which was not compatible with causing disease. However, co-expression with KCNJ16 abolished function in these heteromeric channels almost completely., Conclusion: This study provides an explanation for the pathophysiology of the p.A167V KCNJ10 mutation, which had previously not been considered pathogenic on its own. These findings provide evidence for the functional cooperation of KCNJ10 and KCNJ16. Thus, in vitro ascertainment of KCNJ10 function may necessitate co-expression with KCNJ16., (© 2013 S. Karger AG, Basel.)

Pontocerebellar hypoplasia is a group of autosomal recessive neurodegenerative disorders with prenatal onset. The common characteristics are cerebellar hypoplasia with variable atrophy of the cerebellum and the ventral pons. Supratentorial involvement is reflected by variable neocortical atrophy, ventriculomegaly and microcephaly. Mutations in the transfer RNA splicing endonuclease subunit genes (TSEN54, TSEN2, TSEN34) were found to be associated with pontocerebellar hypoplasia types 2 and 4. Mutations in the mitochondrial transfer RNA arginyl synthetase gene (RARS2) were associated with pontocerebellar hypoplasia type 6. We studied a cohort of 169 patients from 141 families for mutations in these genes, of whom 106 patients tested positive for mutations in one of the TSEN genes or the RARS2 gene. In order to delineate the neuroradiological and clinical phenotype of patients with mutations in these genes, we compared this group with 63 patients suspected of pontocerebellar hypoplasia who were negative on mutation analysis. We found a strong correlation (P < 0.0005) between TSEN54 mutations and a dragonfly-like cerebellar pattern on magnetic resonance imaging, in which the cerebellar hemispheres are flat and severely reduced in size and the vermis is relatively spared. Mutations in TSEN54 are clinically associated with dyskinesia and/or dystonia and variable degrees of spasticity, in some cases with pure generalized spasticity. Nonsense or splice site mutations in TSEN54 are associated with a more severe phenotype of more perinatal symptoms, ventilator dependency and early death. In addition, we present ten new mutations in TSEN54, TSEN2 and RARS2. Furthermore, we show that pontocerebellar hypoplasia type 1 together with elevated cerebrospinal fluid lactate may be caused by RARS2 mutations.

Autosomal-recessive cerebellar ataxias comprise a clinically and genetically heterogeneous group of neurodegenerative disorders. In contrast to their dominant counterparts, unraveling the molecular background of these ataxias has proven to be more complicated and the currently known mutations provide incomplete coverage for genotyping of patients. By combining SNP array-based linkage analysis and targeted resequencing of relevant sequences in the linkage interval with the use of next-generation sequencing technology, we identified a mutation in a gene and have shown its association with autosomal-recessive cerebellar ataxia. In a Dutch consanguineous family with three affected siblings a homozygous 12.5 Mb region on chromosome 3 was targeted by array-based sequence capture. Prioritization of all detected sequence variants led to four candidate genes, one of which contained a variant with a high base pair conservation score (phyloP score: 5.26). This variant was a leucine-to-arginine substitution in the DUF 590 domain of a 16K transmembrane protein, a putative calcium-activated chloride channel encoded by anoctamin 10 (ANO10). The analysis of ANO10 by Sanger sequencing revealed three additional mutations: a homozygous mutation (c.1150&#95;1151del [p.Leu384fs]) in a Serbian family and a compound-heterozygous splice-site mutation (c.1476+1G>T) and a frameshift mutation (c.1604del [p.Leu535X]) in a French family. This illustrates the power of using initial homozygosity mapping with next-generation sequencing technology to identify genes involved in autosomal-recessive diseases. Moreover, identifying a putative calcium-dependent chloride channel involved in cerebellar ataxia adds another pathway to the list of pathophysiological mechanisms that may cause cerebellar ataxia., (Copyright © 2010 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Wolf-Hirschhorn syndrome is characterized by severe growth and mental retardation, microcephaly, seizures and 'Greek helmet' facies, caused by partial deletion of the short arm of chromosome 4. Growth charts are given from 0-4 years of age, based on the study of 101 individuals. Use of these specific growth charts is recommended, because standard growth charts are inapplicable for patients with WHS.

The kidney is the principal organ responsible for the regulation of the body Mg(2+) balance. Identification of the gene defect in hypomagnesemia with secondary hypocalcemia recently elucidated transient receptor potential melastatin 6 (TRPM6) as the gatekeeper in transepithelial Mg(2+) transport, whereas its homolog, TRPM7, is implicated in cellular Mg(2+) homeostasis. The aim of this study was to determine the tissue distribution in mouse and regulation of TRPM6 and TRPM7 by dietary Mg(2+) and hormones. This study demonstrates that TRPM6 is expressed predominantly in kidney, lung, cecum, and colon, whereas TRPM7 is distributed ubiquitously. Dietary Mg(2+) restriction in mice resulted in hypomagnesemia and renal Mg(2+) and Ca(2+) conservation, whereas a Mg(2+)-enriched diet led to increased urinary Mg(2+) and Ca(2+) excretion. Conversely, Mg(2+) restriction significantly upregulated renal TRPM6 mRNA levels, whereas a Mg(2+) enriched diet increased TRPM6 mRNA expression in colon. Dietary Mg(2+) did not alter TRPM7 mRNA expression in mouse kidney and colon. In addition, it was demonstrated that 17beta-estradiol but not 1,25-dihydroxyvitamin D(3) or parathyroid hormone regulates TRPM6 renal mRNA levels. Renal TRPM7 mRNA abundance remained unaltered under these conditions. The renal TRPM6 mRNA level in ovariectomized rats was significantly reduced, whereas 17beta-estradiol treatment normalized TRPM6 mRNA levels. In conclusion, kidney, lung, cecum, and colon likely constitute the main sites of active Mg(2+) (re)absorption in the mouse. In addition, Mg(2+) restriction and 17beta-estradiol upregulated renal TRPM6 mRNA levels, whereas a Mg(2+)-enriched diet stimulated TRPM6 mRNA expression in colon, supporting the gatekeeper function of TRPM6 in transepithelial Mg(2+) transport.

Familial partial lipodystrophy (FPLD) results from coding sequence mutations either in LMNA, encoding nuclear lamin A/C, or in PPARG, encoding peroxisome proliferator-activated receptor gamma (PPARgamma). The LMNA form is called FPLD2 (MIM 151660), and the PPARG form is called FPLD3 (MIM 604367). We now report a 21-yr-old female with FPLD and no coding sequence mutations in either LMNA or PPARG. She was heterozygous for a novel A>G mutation at position -14 of intron B upstream of PPARG exon 1 within the promoter of the PPARgamma4 isoform. Her less severely affected father, who had features of the metabolic syndrome and a paucity of limb and gluteal fat, was also heterozygous for -14A>G. This mutation was absent among 600 alleles from normal Caucasians. A minimal promoter sequence bearing the mutation had significantly reduced promoter activity when used to drive reporter expression in in vitro expression in two cell lines, compared with the wild-type sequence. This is the first report of a human mutation in the promoter of a PPARgamma isoform. Because the mutation affects PPARgamma4 expression and is associated with FPLD, this implies that PPARgamma4 might be important for fat depot distribution and metabolism in vivo.

Type I pseudohypoaldosteronism (PHA-1) is a rare salt wasting syndrome occurring soon after birth, characterized by apathy and severe dehydration accompanied by hyponatremia, hyperkalemia, and metabolic acidosis despite high plasma aldosterone concentrations. The molecular defect involved in the systemic autosomal recessive form of the syndrome has been identified. Mutations in all three genes encoding the epithelial sodium channel (ENaC) lead to a decrease in the channel function, resulting in the disease. We report here two new cases of the autosomal recessive form of PHA-1 in the same family. We found a new homozygous mutation of the gene encoding the alpha ENaC subunit (alphaR492stop). The function of the mutated ENaC channel was assessed in the Xenopus laevis oocyte expression system. The mutant ENaC activity measured with the two-electrode voltage clamp method was drastically decreased compared with the wild type activity, in agreement with the salt-losing phenotype.

A 16-year-old female had mutations in both alleles of the gene encoding her sodium-chloride cotransporter; one of these mutations is newly described. Her clinical findings were not typical because of the absence of hypocalciuria in 24-h urine samples, her maximum urine osmolality (U(osm)) was only 802 mosmol/kg H(2)O, and her plasma magnesium (Mg) concentration (P(Mg)) was easily maintained in the normal range with oral Mg supplements for 1 month. In detailed studies, the calcium/creatinine ratio in spot urines with a U(osm) >700 mosmol/kg H(2)O was very low, except during Mg therapy. Renal medullary function did not appear to be compromised because she had a non-urea U(osm)of approximately 600 mosmol/kg H(2)O, reflecting a very high non-urea osmole excretion rate (due to KCl supplements). At age 18 years, her P(Mg) became persistently low despite Mg therapy. We conclude that the clinical criteria for a provisional diagnosis of Gitelman syndrome should be revised. Hypocalciuria may only be evident initially in concentrated spot urine samples. Urine concentrating ability should include an analysis of the non-urea U(osm), especially when patients are taking large KCl supplements.

Background: At present the genetic defect for autosomal recessive and autosomal dominant hypophosphataemic rickets with hypercalciuria (HHRH) is unknown. Type II sodium/phosphate cotransporter (NPT2) gene is a serious candidate for being the causative gene in either or both autosomal recessive and autosomal dominant HHRH. In the present study we tested this hypothesis in one autosomal recessive family., Methods: The gene structure of human NPT2 is known. We tested the complete open reading frame in the affected siblings by polymerase chain reaction in combination with automatic DNA sequencing for the presence of mutations., Results: We did not observe disease-causing mutations in the NPT2 gene of the affected siblings. A T855C polymorphism resulting in a histidine to arginine transition was present in the open reading frame of NPT2. The polymorphism was present in both affected as well as unaffected family members., Conclusion: The hypothesis that a defect in the NPT2 gene could be an underlying cause for autosomal recessive HHRH could not be sustained in our study.

Parkinson's disease (PD) is a multifactorial disorder, caused by a combination of age, genetics and environmental factors. Nigral cells are susceptible to multiple causes of derangement of normal cell function, all of which may contribute to the same Parkinson phenotype. Autosomal dominant alpha-synuclein-gene PD represents one of the pure genetic forms, whereas cases of sporadic PD probably depend more on age and environmental factors, MPTP-Parkinsonism being the purest example of an environmentally caused Parkinson phenotype. This review suggests that pesticides-herbicides, smoking and head trauma probably represent the most eligible candidates for environmental factors involved in provoking PD or influencing its natural course.

Sarcolipin (SLN) is a low-molecular-weight protein that copurifies with the fast-twitch skeletal muscle sarcoplasmic reticulum Ca2+ ATPase (SERCA1). Genomic DNA and cDNA encoding human sarcolipin (SLN) were isolated and characterized and the SLN gene was mapped to chromosome 11q22-q23. Human, rabbit, and mouse cDNAs encode a protein of 31 amino acids. Homology of SLN with phospholamban (PLN) suggests that the first 7 hydrophilic amino acids are cytoplasmic, the next 19 hydrophobic amino acids form a single transmembrane helix, and the last 5 hydrophilic amino acids are lumenal. The cytoplasmic and transmembrane sequences are not well conserved among the three species, but the lumenal sequence is highly conserved. Like SERCA1, SLN is highly expressed in rabbit fast-twitch skeletal muscle, but it is expressed to a lower extent in slow-twitch muscle and to an even lower extent in cardiac muscle, where SERCA2a and PLN are highly expressed. It is expressed in only trace amounts in pancreas and prostate. SLN and PLN genes resemble each other in having two small exons, with their entire coding sequences lying in exon 2 and a large intron separating the two segments. Brody disease is an inherited disorder of skeletal muscle function, characterized by exercise-induced impairment of muscle relaxation. Mutations in the ATP2A1 gene encoding SERCA1 have been associated with the autosomal recessive inheritance of Brody disease in three families, but not with autosomal dominant inheritance of the disease. A search for mutations in the SLN gene in five Brody families, four of which were not linked to ATP2A1, did not reveal any alterations in coding, splice junction or promoter sequences. The homozygous deletion of C438 in the coding sequence of ATP2A1 in Brody disease family 3, leading to a frameshift and truncation following Pro147 in SERCA1, is the fourth ATP2A1 mutation to be associated with autosomal recessive Brody disease., (Copyright 1997 Academic Press.)

Background: To ascertain whether changes in proteoglycans are involved in the pathogenesis of the nephrotic syndrome in Denys-Drash syndrome (DDS), we analysed the glycosaminoglycan (GAG) content and composition of the glomerular basement membrane (GBM) in one child with this disorder and in children of comparable age who had died from unrelated disorders., Methods: The diagnosis of DDS was confirmed by the presence of a previously described mutation in the WT1 gene (a tumour suppressor gene). The GAG content and composition of the GBM and tubular basement membrane (TBM), both in the Denys-Drash patient as well as age-matched control infants, was analysed by biochemical studies and indirect immunofluorescence studies. Finally we investigated the urinary GAG excretion of the Drash patient., Results: The biochemical studies revealed that the total GAG content in the GBM as well as TBM was comparable in the Drash patient and the control group. However, the GAG composition of the GBM of the patient was clearly different, with relatively more chondroitin sulphate. The urinary GAG content (expressed as mg GAG/mmol creatinine) was elevated in the Denys-Drash patient due to an increased heparan sulphate (HS(GAG)) excretion. Indirect immunofluorescence (IF) studies for the core protein of human GBM heparan sulphate proteoglycan (HSPG) showed a similar linear staining of all renal basement membranes in the patient and the controls. A monoclonal antibody directed against the HS chain of HSPG (MoAb 403) displayed a strong GBM and a weak TBM staining of normal kidneys. Kidney tissue from the Drash patient displayed a reduced staining of the GBM with MoAb 403. IF studies for chondroitin sulphate proteoglycan (CSPG) showed increased staining of the mesangium and glomerular capillary loops in the Denys-Drash patient which is in agreement with the biochemical studies. No discernible differences in distribution or quality of staining with antibodies against collagen type IV and laminin were observed., Conclusions: These biochemical and immunohistochemical results indicate that in our patient the proteoglycan composition of the GBM is altered. This alteration may play a role in the pathogenesis of proteinuria in this syndrome.