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Purpose. To identify the molecular etiology of a Chinese family with nonsyndromic macular dystrophy. Methods. Ophthalmic examinations were performed, and genomic DNA was extracted from available family members. Whole exome sequencing of two members (the proband and her unaffected mother) and Sanger sequencing in available family members were performed to screen potential pathogenic variants. Results. Novel compound heterozygous variants, c.1066C>T (p.Pro356Ser) and c.1102+2T>C, in the major facilitator superfamily domain containing 8 gene (MFSD8) were suspected to be involved in this family’s macular dystrophy phenotype. The novel c.1066C>T variant in the MFSD8 gene probably resulted in substitution of serine for proline at the 356th residue and was predicted to be “uncertain significance” through in silico analyses. The novel c.1102+2T>C variant in the MFSD8 gene was likely to affect the splicing form and predicted to be “pathogenic.” Conclusion. The novel compound heterozygous variants, c.1066C>T (p.Pro356Ser) and c.1102+2T>C, in the MFSD8 gene are likely responsible for the isolated macular dystrophy phenotype in this family. This study enlarged the MFSD8 gene mutant spectrum and might provide more accurate genetic counseling for this family.

Parkinson's disease (PD) is the fastest-growing neurodegenerative disorder. Aging, environmental factors, and genetics are considered as risk factors. The alpha-synuclein gene (SNCA), the first pathogenic gene identified in a familial form of PD, was indisputably involved as a heritable component for familial and sporadic PD. In this study, whole-exome sequencing and Sanger sequencing were performed to evaluate the association between the SNCA gene variants and PD. The genetic data of 438 clinically diagnosed patients with PD and 543 matched control populations of the Han Chinese were analyzed. The literature review of SNCA variants for 231 cases reported in 89 articles was extracted from the PubMed and the Movement Disorder Society Genetic mutation database. No potentially causative variant(s) in the SNCA gene, excepting two single-nucleotide nonsynonymous variants c.158C>T (p.A53V, rs542171324) and c.349C>T (p.P117S, rs145138372), were detected. There was no statistically significant difference in the genotypic or allelic frequencies for either variant between the PD group and the control group (all P > 0.05). No copy number variants of the SNCA gene were detected. The results of this study suggest that the variants in the exons of the SNCA gene may have less or no role in the development of PD in the Han Chinese populations. The literature review suggests that psychiatric signs and cognitive decline/dementia were more common among patients with SNCA duplication or triplication (psychiatric signs: χ2 = 7.892, P = 0.005; cognitive decline/dementia: χ2 = 8.991, P = 0.003).

Primary ciliary dyskinesia (PCD) is a group of genetically and clinically heterogeneous disorders with motile cilia dysfunction. It is clinically characterized by oto‐sino‐pulmonary diseases and subfertility, and half of the patients have situs inversus (Kartagener syndrome). To identify the genetic cause in a Han‐Chinese pedigree, whole‐exome sequencing was conducted in the 37‐year‐old proband, and then, Sanger sequencing was performed on available family members. Minigene splicing assay was applied to verify the impact of the splice‐site variant. Compound heterozygous variants including a splice‐site variant (c.1974‐1G>C, rs1359107415) and a missense variant (c.7787G>A, p.(Arg2596Gln), rs780492669), in the dynein axonemal heavy chain 11 gene (DNAH11) were identified and confirmed as the disease‐associated variants of this lineage. The minigene expression in vitro revealed that the c.1974‐1G>C variant could cause skipping over exon 12, predicted to result in a truncated protein. This discovery may enlarge the DNAH11 variant spectrum of PCD, promote accurate genetic counselling and contribute to PCD diagnosis.

In this report, we described a large Han-Chinese family which presents with various phenotypes from unaffected to manifested nystagmus in females. Infantile nystagmus (IN) is characterized by bilateral, involuntary, and periodic eyeball oscillation, occurring at birth or within the first 6 months. The most common inheritance pattern of IN is an X-linked form with incomplete penetrance among females, and the FERM domain containing 7 gene (FRMD7) is a main disease-causing gene. A combination of exome sequencing and Sanger sequencing, as well as detailed clinical examinations were performed on the Chinese IN family. An FRMD7 c.47T>C (p.Phe16Ser) variant was proposed as the disease-causing variant. Incomplete penetrance was found in females with the FRMD7 c.47T>C variant, and hemizygous male affected subjects presented more severe manifestations compared to heterozygous female affected subjects. These findings could enhance genetic counseling and antenatal diagnosis of IN.

Background Haemophilia A (HA), inherited via an X-linked recessive pattern, is the most common severe lifelong bleeding disorder caused by mutations in the coagulation factor VIII gene (F8). It has significant socio-economic effects due to its long course of disease and high cost of care. These impacts argue for a more accurate genetic diagnosis in an increasingly complex clinical environment. Methods A three-generation Han-Chinese family with mild HA was recruited in the study. Exome sequencing was performed in the index case to detect potential disease-causing mutations, and Sanger sequencing was applied to verify the mutation in the family. Results A hemizygous c.602G > A variant in the F8 gene, leading to a single amino acid substitution at codon 201 from glycine to glutamic acid (p.G201E) within the factor VIII (FVIII) A1 domain, was identified in the HA family. This mutation detected in the proband was found in his affected sibling, while it was absent in the unaffected family member and the two hundred ethnically-matched controls. The mutation affects an evolutionary conserved residue, which may impact the tertiary structure of FVIII. Conclusion The study findings should provide for more dependable and precise genetic counseling which may assist in perfecting family management.

Background: Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an autosomal-dominant, inherited, systemic, vascular disorder primarily involving the small arteries. It is characterized by migraine, recurrent ischemic strokes, cognitive decline, and dementia. Mutations in the Notch receptor 3 gene (NOTCH3) and the HtrA serine peptidase 1 gene (HTRA1) are 2 genetic causes for CADASIL. The NOTCH3 gene, located on chromosome 19p13.12, is the most common disease-causing gene in CADASIL. Objective: To investigate genetic causes in 2 unrelated Han-Chinese patients with presentations strongly suggestive of CADASIL. Methods: Exome sequencing was performed on both patients and potential pathogenic mutations were validated by Sanger sequencing. Results: This study reports on 2 unrelated Han-Chinese patients with presentations strongly suggestive of CADASIL, identifying that NOTCH3 mutations were the genetic cause. A common mutation, c.268C>T (p.Arg90Cys), and a novel mutation, c.331G>T (p.Gly111Cys) in the NOTCH3 gene, were detected and confirmed in the patients, respectively, and were predicted to be deleterious based on bioinformation analyses. Conclusions: We identified 2 NOTCH3 mutations as likely genetic causes for CADASIL in these 2 patients. Our findings broaden the mutational spectrum of the NOTCH3 gene accountable for CADASIL. Clinical manifestations supplemented with molecular genetic analyses are critical for accurate diagnosis, the provision of genetic counseling, and the development of therapies for CADASIL.

Background Macular corneal dystrophy (MCD), a rare autosomal recessive disorder, is caused by pathogenic mutations in the carbohydrate sulfotransferase 6 gene (CHST6) and is characterized by bilateral progressive stromal clouding and vision loss. Corneal transplantation is often necessary. This study aimed to identify disease-causing mutations in a Han-Chinese MCD patient. Methods A 37-year-old female diagnosed with MCD was recruited. The clinical materials were observed and described, and peripheral blood sample was extracted. Whole exome sequencing (WES) and Sanger sequencing were used to reveal genetic defects. The pathogenicity of identified mutations was assessed using in silico analysis. Results The patient had typical features of MCD, including decreased vision, multiple irregular gray-white corneal opacities, and corneal thinning. A novel nonsense mutation c.544C>T (p.Gln182Ter) and a validated missense mutation c.631C>G (p.Arg211Gly) were identified in the CHST6 gene coding region, both classified as "pathogenic" following the American College of Medical Genetics and Genomics standards and guidelines. Conclusions This study reports a Han-Chinese MCD patient with a novel nonsense mutation c.544C>T (p.Gln182Ter) and a recurrent missense mutation c.631C>G (p.Arg211Gly), which expand the spectrum of genetic mutations. The results of this study extend genotype-phenotype correlations between the CHST6 gene mutations and MCD clinical findings, contributing to a more accurate diagnosis and the development of potential gene-targeted MCD therapies. Keywords Carbohydrate sulfotransferase 6 gene (CHST6); compound heterozygous mutations; Han Chinese family; macular corneal dystrophy (MCD).

Limb-girdle muscular dystrophies (LGMD) are hereditary genetic disorders characterized by progressive muscle impairment which predominantly include proximal muscle weaknesses in the pelvic and shoulder girdles. This article describes an attempt to identify genetic cause(s) for a LGMD pedigree via a combination of whole exome sequencing and Sanger sequencing. Digenic variants, the titin gene (TTN) c.19481T>G (p.Leu6494Arg) and the trafficking protein particle complex 11 gene (TRAPPC11) c.3092C>G (p.Pro1031Arg), co-segregated with the disease phenotype in the family, suggesting their possible pathogenicity.

Heterotaxy (HTX), a condition characterized by internal organs not being arranged as expected relative to each other and to the left-right axis, is often accompanied with congenital heart disease (CHD). The purpose was to detect the pathogenic variants in a Chinese family with HTX and CHD. A non-consanguineous Han Chinese family with HTX and CHD, and 200 unrelated healthy subjects were enlisted. Exome sequencing and Sanger sequencing were applied to identify the genetic basis of the HTX family. Compound heterozygous variants, c.3426-1G>A and c.4306C>T (p.(Arg1436Trp)), in the dynein axonemal heavy chain 11 gene (DNAH11) were identified in the proband via exome sequencing and further confirmed by Sanger sequencing. Neither c.3426-1G>A nor c.4306C>T variant in the DNAH11 gene was detected in 200 healthy controls. The DNAH11 c.3426-1G>A variant was predicted as altering the acceptor splice site and most likely affecting splicing. The DNAH11 c.4306C>T variant was predicted to be damaging, which may reduce the phenotype severity. The compound heterozygous variants, c.3426-1G>A and c.4306C>T, in the DNAH11 gene might be the pathogenic alterations resulting in HTX and CHD in this family. These findings broaden the variant spectrum of the DNAH11 gene and increase knowledge used in genetic counseling for the HTX family.

Background Tuberous sclerosis complex (TSC) is an autosomal dominant disorder with a variety of clinical findings. Variants in the TSC complex subunit 1 gene (TSC1) or the TSC complex subunit 2 gene (TSC2) are responsible for TSC. Methods Physical examinations, computed tomography scans, and light microscopy analyses were performed on the TSC patient from a Han-Chinese pedigree. Whole-exome sequencing combined with Sanger sequencing were performed on the family members. Results The TSC patient showed typical clinical features, including facial angiofibromas, gingival fibromas, a shagreen patch, hypomelanotic macules, ungual fibromas, subependymal nodules, multiple pulmonary cysts, and renal hamartomas. A de novo heterozygous c.5146delG (p.Ala1716Profs*110) variant in the TSC2 gene was identified in the TSC patient of the Han-Chinese family. To our knowledge, this is the first report of the TSC2 c.5146delG variant associated with TSC. Conclusion The study expanding the disease-causing variant spectrum, suggests that whole-exome sequencing combined with Sanger sequencing may be a method for TSC diagnosis and differential diagnosis, and may facilitate the development of genetic counseling and targeted gene therapy for this disease.

The function and position of the internal organs within the human body are based on left-right (LR) asymmetry. Human LR asymmetry disorders are characterized by abnormal LR asymmetric arrangement of the internal organs resulting from defective embryonic nodal cilia and nodal signaling pathway. The coiled-coil domain containing 114 gene (CCDC114) is related to the biogenesis of cilia and attachment of the outer dynein arms (ODAs) to the axoneme of cilia. Mutations in the CCDC114 gene are reported to cause a subtype of primary ciliary dyskinesia (PCD) named ciliary dyskinesia, primary, 20 (CILD20). Patients with CCDC114 mutations present with a type of ciliopathy with high clinical heterogeneity. In the present study, a Han-Chinese patient with situs inversus was recruited. Exome sequencing was performed on this patient combined with variant validation by Sanger sequencing. A homozygous variant c.584T>C (p.L195P) in the CCDC114 gene was identified as the likely genetic cause for situs inversus in this patient. The findings of our study extend the mutational spectrum of the CCDC114 gene, and contribute to clarifying the pathogenesis of human ciliopathies and benefit genetic counseling.

Familial amyloid polyneuropathies (FAPs) are life-threatening, autosomal dominant diseases resulting, in most instances, from transthyretin gene (TTR) variants. A small number of TTR variants lead to leptomeningeal amyloidosis (LA), which is a rare FAP subtype with late-onset central nervous system (CNS) impairment symptoms. Previous studies suggest that LA's CNS selectivity was due to complete endoplasmic reticulum-associated degradation of highly destabilized mutants in peripheral tissues. LA's later age at onset (AAO) was due to lower choroid plexus secretory efficacy. This study reports on a family with LA, including six symptomatic and three presymptomatic members. The LA diagnosis was confirmed by leptomeningeal enhancement on contrast MRI, elevated cerebrospinal fluid protein levels, and positive Congo red staining. The predominant symptoms included headaches, dizziness, vomiting, hallucinations, and cognitive impairments which associated with obstructive hydrocephalus. The TTR p.D38G variant with the lowest secretory efficacy was identified as the genetic cause by whole exome sequencing. The family had a statistically significantly earlier mean AAO of 31.3 ± 7.4 (p = 0.001). These uncommon phenotypes indicate unknown factors influencing the progress of CNS impairment via TTR mutants. Medical imaging examinations suggest the potential early diagnosis value of contrast MRI and the importance of ependyma involvement in LA. LA genetic and clinical data were reviewed and summarized. These findings expand the FAPs' phenotypic spectrum and are valuable in FAP diagnosis, treatment, and further research.

GNE myopathy is a rare, recessively inherited, early adult‐onset myopathy, characterized by distal and proximal muscle degeneration which often spares the quadriceps. It is caused by mutations in the UDP‐N‐acetylglucosamine 2‐epimerase/N‐acetylmannosamine kinase gene (GNE). This study aimed to identify the disease‐causing mutation in a three‐generation Han‐Chinese family with members who have been diagnosed with myopathy. A homozygous missense mutation, c.1627G>A (p.V543M) in the GNE gene co‐segregates with the myopathy present in this family. A GNE myopathy diagnosis is evidenced by characteristic clinical manifestations, rimmed vacuoles in muscle biopsies and the presence of biallelic GNE mutations. This finding broadens the GNE gene mutation spectrum and extends the GNE myopathy phenotype spectrum.

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder primarily characterized by multiple cafe-au-lait macules, peripheral neurofibromas, skinfold freckling, and Lisch nodules. The causative genetic factor is the neurofibromin 1 gene (NF1), which encodes a Ras GTPase-activating protein called neurofibromin. NF1 variants may lead to loss of neurofibromin function and activation of downstream cell growth. This study aims to discover the disease-causing variants responsible for NF1 in two Han Chinese families by using exome sequencing combined with Sanger sequencing. A recurrent missense variant c.269T>C (p.Leu90Pro) and a novel nonsense variant c.2993dupA (p.Tyr998*) in the NF1 gene were identified. These variants co-segregated with the disorder in the pedigrees and were absent in the normal controls. The results broaden the NF1 mutation spectrum responsible for NF1. This may be helpful in genetic counseling, clinical management, and gene-targeted therapies for NF1.

Essential tremor (ET) is one of the most common adult-onset movement disorders. ET and Parkinson's disease (PD) overlap clinically and pathologically, which prompted this investigation into the association of PD risk variants in ET patients. This study was designed to explore the role of variants of two PD-related genes LRRK1 and LRRK2 in a Han Chinese ET population.Genetic analysis of LRRK1, rs2924835, and LRRK2, rs34594498, rs34410987, and rs33949390 variants was conducted on 200 Han Chinese patients with ET and 434 ethnically matched normal controls.No statistically significant differences were identified in either genotypic or allelic frequencies of variants between the ET patients and the control cohort (all p 0.05). Haplotype analysis of three LRRK2 variants (rs34594498, rs34410987, and rs33949390) showed no haplotypes displayed an association with ET risk (all p 0.05).The data suggest that LRRK1 variant (rs2924835) and LRRK2 variants (rs34594498, rs34410987, and rs33949390) are not associated with ET in this Han Chinese population.

Tourette syndrome (TS) is a complex neuropsychiatric disorder with chronic motor and vocal tics. Though the etiology is elusive, strong evidence for a genetic contribution to TS has been established. To date, various chromosomal or genetic alterations have been implicated in its pathogenesis. Recently, the deletion in the arylacetamide deacetylase gene (AADAC) was reported to be associated with TS. To investigate the association between the AADAC gene variants and TS, we conducted genetic analysis of the AADAC gene in 200 Han Chinese patients and 300 ethnicity-matched normal controls. Two variants, including a heterozygous splice-site variant, c.361 + 1G > A (rs762169706), and a missense variant, c.744A > T (p.R248S, rs186388618), were identified in two unrelated patients. The c.361 + 1G > A variant, absent in 300 ethnicity-matched controls, led to the deletion of exon 2 in AADAC mRNA, probably associated with development of TS. The c.744A > T variant, predicted to be damaging, was identified in two normal controls. The findings indicate that the AADAC gene c.361 + 1G > A variant may be a potential candidate factor for TS development, though further investigations are warranted.

Background/Aims: Epidermolytic palmoplantar keratoderma (EPPK) is an autosomal dominant genodermatosis. It is characterized by diffuse yellow keratoses on the palmoplantar epidermis, with an erythematous border. The keratin 9 gene (KRT9) and less frequently the keratin 1 gene (KRT1) are responsible for EPPK. This study aims to identify and analyse genetic defects responsible for EPPK in a Han Chinese pedigree. Methods: A four-generation Han Chinese pedigree containing five individuals affected with EPPK was recruited. Exome sequencing, Sanger sequencing, and bioinformatics tools were conducted to identify the mutation in this pedigree. HaCaT cells were transfected with either wild-type or mutated KRT9. Confocal laser immunofluorescence assay, imaging processing, and statistical analysis were performed to evaluate wild-type and mutant KRT9 groups. Results: A novel heterozygous c.1369C>T transition (p.Leu457Phe) in exon 6 of the KRT9 gene was identified in four patients. It co-segregated with the disorder in the family. Functional analysis showed that withdrawal of the filament network from the cell periphery and particle formation were present in about 10% of Leu457Phe-transfected HaCaT cells, while approximately 3% of cells transfected with wild-type KRT9 showed this phenotype. The particles in mutant group were larger than that in wild-type group (P-value < 0.05). Conclusion: The variant may be the disease-causing missense mutation and produce dominant negative effects by interrupting keratin network formation. This study indicates the pathogenic role of the KRT9 gene mutation in this pedigree with EPPK, and may be helpful in genetic counseling, prenatal diagnosis and gene-targeted therapies of EPPK.

Familial amyloid polyneuropathy (FAP) is a dominantly inherited disorder. This study aims to explore the genetic features of a Han Chinese family with FAP, characterized by bloating, alternating diarrhea and constipation, and weakness in his feet. Amyloid presented histologically in the vessel walls of hepatic portal area and nerves of the surgically excised liver specimens from the proband by hematoxylin and eosin staining. Amyloid deposition was further confirmed with Congo red treatment. A c.349G>T transversion (p.Ala117Ser) in TTR gene exon 4 was identified in the proband with typical autonomic neuropathy and peripheral motor neuropathy, as well as in his asymptomatic son. The variant was not detected in 200 normal ethnically matched controls. These findings provide new insights into FAP cause and diagnosis and have implications for genetic counseling.

Usher syndrome (USH) is an autosomal recessive disorder characterized by sensorineural hearing loss, progressive visual loss and night blindness due to retinitis pigmentosa (RP), with or without vestibular dysfunction. The purpose of this study was to detect the causative gene in a consanguineous Chinese family with USH. A c.3696_3706del (p.R1232Sfs*72) variant in the myosin VIIa gene (MYO7A) was identified in the homozygous state by exome sequencing. The co‑segregation of the MYO7A c.3696_3706del variant with the phenotype of deafness and progressive visual loss in the USH family was confirmed by Sanger sequencing. The variant was absent in 200 healthy controls. Therefore, the c.3696_3706del variant may disrupt the interaction between myosin VIIa and other USH1 proteins, and impair melanosome transport in retinal pigment epithelial cells. Notably, bilateral auditory brainstem responses were absent in two patients of the USH family, while distortion product otoacoustic emissions were elicited in the right ears of the two patients, consistent with clinical diagnosis of unilateral auditory neuropathy spectrum disorder. These data suggested that the homozygous c.3696_3706del variant in the MYO7A gene may be the disease‑causing mutation for the disorder in this family. These findings broaden the phenotype spectrum of the MYO7A gene, and may facilitate understanding of the molecular pathogenesis of the disease, and genetic counseling for the family.

Muscular dystrophy‐dystroglycanopathy (MDDG) is a genetically and clinically heterogeneous group of muscular disorders, characterized by congenital muscular dystrophy or later‐onset limb‐girdle muscular dystrophy accompanied by brain and ocular abnormalities, resulting from aberrant alpha‐dystroglycan glycosylation. Exome sequencing and Sanger sequencing were performed on a six‐generation consanguineous Han Chinese family, members of which had autosomal recessive MDDG. Compound heterozygous mutations, c.1338+1G>A (p.H415Kfs*3) and c.1457G>C (p.W486S, rs746849558), in the protein O‐mannosyltransferase 1 gene (POMT1), were identified as the genetic cause. Patients that exhibited milder MDDG manifested as later‐onset progressive proximal pelvic, shoulder girdle and limb muscle weakness, joint contractures, mental retardation and elevated creatine kinase, without structural brain or ocular abnormalities, were further genetically diagnosed as MDDGC1. The POMT1 gene splice‐site mutation (c.1338+1G>A) which leads to exon 13 skipping and results in a truncated protein may contribute to a severe phenotype, while the allelic missense mutation (p.W486S) may reduce MDDG severity. These findings may expand phenotype and mutation spectrum of the POMT1 gene. Clinical diagnosis supplemented with molecular screening may result in more accurate diagnoses of, prognoses for, and improved genetic counselling for this disease.

Background Ellis‐van Creveld syndrome (EVC), a very rare genetic skeletal dysplasia, is clinically characterized by a tetrad consisting of chondrodystrophy, polydactyly, ectodermal dysplasia, and cardiac anomalies. The aim of this study was to identify the genetic defect for EVC in a five‐generation consanguineous Han‐Chinese pedigree. Methods A five‐generation, 12‐member Han‐Chinese pedigree was enrolled in this study. Exome sequencing was applied in the proband to screen potential genetic variant(s), and then Sanger sequencing was used to identify the variant in family members and 200 unrelated ethnicity‐matched controls. Results A novel homozygous variant, c.2014C>T, p.(Q672*), in the EvC ciliary complex subunit 1 gene (EVC), was detected in the patient, which was cosegregated with the disease in the family and absent in the controls. Conclusion The identified novel homozygous EVC variant, c.2014C>T, p.(Q672*), was responsible for EVC in this Han‐Chinese pedigree. The findings in this study extend the EVC mutation spectrum and may provide new insights into EVC causation and diagnosis with implications for genetic counseling and clinical management.

Kartagener syndrome (KS), a subtype of primary ciliary dyskinesia (PCD), is characterized by bronchiectasis, chronic sinusitis, male infertility and situs inversus. KS is a genetically heterogeneous disease that is inherited in an autosomal recessive form; however, X-linked inheritance has also been reported. As of this writing [late 2020], at least 34 loci, most of which have known genes, have been reported in the literature as associating with KS. In the present study, we identified a frame shift mutation, c.167delG (p.G56Dfs*26), in the coiled-coil domain containing 151 gene (CCDC151) responsible for KS in a Han-Chinese family. To our knowledge, this is the first report of a CCDC151 c.167delG mutation in the KS patient. These findings may expand the CCDC151 mutation spectrum of KS, and contribute to future genetic counseling and gene-targeted therapy for this disease.

Retinitis pigmentosa (RP), the most common type of inherited retinal degeneration causing blindness, initially manifests as severely impaired rod function followed by deteriorating cone function. Mutations in the rhodopsin gene (RHO) are the most common cause of autosomal dominant RP (adRP). The present study aims to identify the disease-causing mutation in a numerous, four-generation Han-Chinese family with adRP detected by whole exome sequencing and Sanger sequencing. Afflicted family members present classic adRP along with heterogeneous clinical phenotypes including differing refractive errors, cataracts, astigmatism and epiretinal membranes. A missense mutation, c.403C>T (p.R135W), in the RHO gene was identified in nine subjects and it co-segregated with family members. The mutation is predicted to be disease-causing and results in rhodopsin protein abnormalities. The present study extends the genotype–phenotype relationship between RHO gene mutations and adRP clinical findings. The results have implications for familial genetic counseling, clinical management and developing RP target gene therapy strategies.

Background:Alport syndrome (AS) is an inherited familial nephropathy, characterized by progressive hematuric nephritis, bilateral sensorineural hypoacusis and ocular abnormalities. X-linked AS (XLAS) is the major AS form and is clinically heterogeneous, and it is associated with defects in the collagen type IV alpha 5 chain gene (COL4A5).Objective:The purpose of this research is to detect the genetic defect responsible for renal disorder in a 3-generation Han-Chinese pedigree.Methods:Detailed family history and clinical data of the family members were collected and recorded. Whole exome sequencing (WES) was applied in the proband to screen potential genetic variants, and then Sanger sequencing was used to verify the variant within the family. Two hundred unrelated ethnically matched normal individuals (male/female: 100/100, age 37.5 ± 5.5 years) without renal disorder were recruited as controls.Results:Three patients (I:1, II:1 and II:2) presented microscopic hematuria and proteinuria, and the patient I:1 developed uremia and end stage renal disease (ESRD) by age 55 and showed sensorineural hearing loss. Patient II:2 developed mild left ear hearing loss. Cataracts were present in patients I:1 and II:1. A COL4A5 gene missense variant, c.2156G>A (p.G719E), located in the Gly-X-Y repeats of exon 28, was identified to co-segregate with the renal disorder in this family. The variant was absent in 200 ethnically matched controls.Conclusion:By conducting WES and Sanger sequencing, a COL4A5 missense variant, c.2156G>A (p.G719E), was identified to co-segregate with the renal disorder, and it is possible that this variant is the genetic cause of the disorder in this family. Our study may extend the mutation spectrum of XLAS and may be useful for genetic counseling of this family. Further functional studies associated with genetic deficiency are warranted in the following research.

Breast cancer (BC) is the most common female cancer found worldwide. It is responsible for 25% of all cancer patients in females. Hereditary BC accounts for about 5–10% of all BC cases. The breast cancer 1 gene (BRCA1) and the breast cancer 2 gene (BRCA2) are the two most-studied BC susceptibility genes. Genetic testing for disease-causing mutations in BRCA1, BRCA2, and other BC susceptibility genes is strongly recommended for members of families having a BC family history. The present study found a heterozygous c.5722_5723del mutation in the BRCA2 exon 11 of a large Han-Chinese BC family using whole exome sequencing and Sanger sequencing. It may cause DNA double-strand breaks repair dysfunction by disturbing homologous recombination, further resulting in BC. The study findings may help supplement and further improve genetic testing strategies and BC risk estimation methodologies in China.

Background Osteogenesis imperfecta (OI), a genetically determined connective tissue disorder, is characterized by increased bone fragility and reduced bone mass. Clinical presentation severity ranges from very mild types with nearly no fractures to intrauterine fractures and perinatal lethality. It can be accompanied by blue sclerae, dentinogenesis imperfecta (DI), hearing loss, muscle weakness, ligament laxity, and skin fragility. This study sought to identify pathogenic gene variants in a four‐generation Han Chinese family with OI type I. Methods In order to unveil the molecular genetic factors underlying the disease phenotype, whole exome sequencing in a member, with OI type I, of a Han Chinese family from Hunan, China was performed. The variant identified by whole exome sequencing was further tested by Sanger sequencing in the family members. Results A heterozygous missense variant (NM_000089.3: c.3197G>T; NP_000080.2: p.Gly1066Val) in the collagen type I alpha 2 chain gene (COL1A2) was identified in four patients. It co‐segregated with the disease in the family. Conclusion The sequence variant may be a disease‐causing factor resulting in abnormal type I procollagen synthesis and leading to OI type I. This finding has significant implications for genetic counseling and clinical monitoring of high‐risk families and may be helpful for understanding pathogenic mechanism of OI and developing therapies.

Stargardt disease (STGD1, OMIM 248200) is a common hereditary juvenile or early adult onset macular degeneration. It ultimately leads to progressive central vision loss. Here, we sought to identify gene mutations associated with STGD1 in a three-generation Han Chinese pedigree by whole exome sequencing and Sanger sequencing. Two novel potentially pathogenic variants in a compound heterozygous state, c.3607G>T (p.(Gly1203Trp)) and c.6722T>C (p.(Leu2241Pro)), in the ATP binding cassette subfamily A member 4 gene (ABCA4) were identified as contributing to the family’s STGD1 phenotype. These variants may impact the ABCA4 protein structure and reduce the retinal-activated ATPase activity, leading to abnormal all-trans retinal accumulation in photoreceptor outer segments and in retinal pigment epithelium cells. The present study broadens the mutational spectrum of the ABCA4 responsible for STGD1. A combination of whole exome sequencing and Sanger sequencing is likely to be a time-saving and cost-efficient approach to screen pathogenic variants in genetic disorders caused by sizable genes, as well as avoiding misdiagnosis. These results perhaps refine genetic counseling and ABCA4-targetted treatments for families affected by STGD1.

Objective Thin basement membrane nephropathy (TBMN), an autosomal dominant inherited condition in general, is characterized clinically by persistent hematuria and pathologically by thinning of glomerular basement membrane. TBMN is occasionally accompanied with proteinuria, hypertension and renal impairment in some cases. The aim of this study is to explore the genetic defect in a Chinese pedigree with familial hematuria. Design and methods A four-generation Chinese Han pedigree with familial hematuria was recruited. Exome sequencing was conducted in the proband diagnosed as TBMN, followed by verification in the proband and other family members with Sanger sequencing. Results A novel missense variant, c.4616C > G (p.S1539C), in the fibronectin 1 gene (FN1), was identified, and it co-segregated with the disease condition in the family. It was not observed in 100 normal controls. Conclusions A missense variant in the FN1 gene is possibly responsible for familial hematuria or TBMN in this family, which may broaden the phenotype and mutation spectrums of the FN1 gene. A male patient in this family progressed to end-stage renal disease requiring kidney transplantation, supporting that familial hematuria or TBMN may not always be as benign as generally thought. The findings may have new implications for clinical monitoring and genetic counseling of the family, and may also help understand the pathogenesis.

Type II collagen, comprised of three identical alpha-1(II) chains, is the major collagen synthesized by chondrocytes, and is found in articular cartilage, vitreous humour, inner ear and nucleus pulposus. Mutations in the collagen type II alpha-1 gene (COL2A1) have been reported to be responsible for a series of abnormalities, known as type II collagenopathies. To date, 16 definite disorders, inherited in an autosomal dominant or recessive pattern, have been described to be associated with the COL2A1 mutations, and at least 405 mutations ranging from point mutations to complex rearrangements have been reported, though the underlying pathogenesis remains unclear. Significant clinical heterogeneity has been reported in COL2A1-associated type II collagenopathies. In this review, we highlight current knowledge of known mutations in the COL2A1 gene for these disorders, as well as genetic animal models related to the COL2A1 gene, which may help us understand the nature of complex phenotypes and underlying pathogenesis of these conditions.

Parkinson's disease (PD) is a common age-dependent neurodegenerative movement disorder related to multiple factors, and genetic factors play an important role in the pathogenesis of PD. Variants in the methylenetetrahydrofolate reductase gene (MTHFR), a gene encoding a folate-dependent enzyme that is involved in homocysteine metabolism, have been reported to be associated with PD. To explore the role of the MTHFR gene in the development of PD in Chinese Han population, we analyzed two MTHFR variants (rs1801131 and rs1801133) in a patient cohort consisting of 512 patients with PD from mainland China and a control cohort consisting of 512 age, gender and ethnicity matched normal subjects. Statistically significant differences in genotypic and allelic frequencies were detected in the MTHFR variant rs1801133 (P=0.022 and 0.007, respectively; odds ratio=0.780, 95% confidence interval=0.651-0.934). In addition, the A-T haplotype of rs1801131-rs1801133 showed a protective role against PD development (P=0.007, odds ratio=0.779, 95% confidence interval=0.650-0.933). Our results suggested that the T allele of rs1801133 variant and A-T haplotype of rs1801131-rs1801133 in the MTHFR gene may decrease the risk of developing PD in Chinese Han population from mainland China.

Background & objectives: Alport syndrome (AS) is an inherited disorder characterized by glomerulonephritis and end-stage renal disease (ESRD). The aim of this study was to identify the gene responsible for the glomerulopathy in a Chinese family with autosomal dominant AS using exome sequencing. Methods: A 4-generation, 30-member Chinese Han family was enrolled in this study. Exome sequencing was conducted in the proband of the family, and then direct sequencing was performed in family members of the pedigree and 100 normal controls. Results: A novel frameshift mutation, c.3213delA (p.Gly1072GlufsFNx0169), in the collagen type IV alpha-4 gene (COL4A4) was found to be the genetic cause. Neither sensorineural hearing loss nor ocular abnormalities were present in the patients of this family. Other clinical features, such as age of onset, age of ESRD occurring and disease severity, varied among the patients of this family. Interpretation & conclusions: A novel frameshift mutation, c.3213delA (p.Gly1072GlufsFNx0169) in the COL4A4 gene, was identified in the Chinese pedigree with autosomal dominant AS. Our findings may provide new insights into the cause and diagnosis of AS and also have implications for genetic counselling.

Protein O-mannosyltransferase 1 (POMT1) is a critical enzyme participating in the first step of protein O-mannosylation. Mutations in the coding gene, POMT1, have been described to be related to a series of autosomal recessive disorders associated with defective alpha-dystroglycan glycosylation, later termed muscular dystrophy-dystroglycanopathies (MDDGs). MDDGs are characterized by a broad phenotypic spectrum of congenital muscular dystrophy or later-onset limb-girdle muscular dystrophy, accompanied by variable degrees of intellectual disability, brain defects, and ocular abnormalities. To date, at least 76 disease-associated mutations in the POMT1 gene, including missense, nonsense, splicing, deletion, insertion/duplication, and insertion-deletion mutations, have been reported in the literature. In this review, we highlight the present knowledge of the identified disease-associated POMT1 gene mutations and genetic animal models related to the POMT1 gene. This review may help further normative classification of phenotypes, assist in definite clinical and genetic diagnoses, and genetic counseling, and may comprehensively improve our understanding of the basis of complex phenotypes and possible pathogenic mechanisms involved.

Retinitis pigmentosa (RP) is a group of hereditary, degenerative retinal disorders characterized by progressive retinal dysfunction, outer retina cell loss, and retinal tissue atrophy. It eventually leads to tunnel vision and legal or total blindness. Here, we aimed to reveal the causal gene and mutation contributing to the development of autosomal recessive RP (arRP) in a consanguineous family. A novel homozygous mutation, c.4845delT (p.K1616Rfs*46), in the ATP-binding cassette subfamily A member 4 gene (ABCA4) was identified. It may reduce ABCA4 protein activity, leading to progressive degeneration of both rod and cone photoreceptors. The study extends the arRP genotypic spectrum and confirms a genotype–phenotype relationship. The present study may also disclose some new clues for RP genetic causes and pathogenesis, as well as clinical and genetic diagnosis. The research findings may contribute to improvement in clinical care, therapy, genetic screening, and counseling.

Limb-girdle muscular dystrophies (LGMD) are a highly heterogeneous group of genetic myopathies characterized by progressive proximal pelvic and/or shoulder girdle muscle weakness, with the onset ages ranging from early childhood to late adulthood. The identification of these dystrophies through genetic testing will not only inform long-term prognosis but will also assist in directing care more efficiently, including more frequent cardiorespiratory monitoring and prophylactic treatments. The aim of this study was to identify the responsible gene in a five-generation Chinese Han pedigree with autosomal recessive LGMD. Exome sequencing was conducted and a novel mutation c.107788T>C (p.W35930R) in the titin gene (TTN) was identified. The mutation co-segregated with the disorder in the family and was absent in normal controls. Our discovery broadens the mutation spectrum of the TTN gene associated with LGMD2J.

Parkinson's disease (PD) is the second most common neurodegenerative disorder and has an elusive etiology. It is likely multifactorial, and genetic defects contribute to its pathogenesis. At least 25 genetic loci and 20 monogenic genes have been identified in monogenic PD. Recessive F-box protein 7 gene (FBXO7) mutations reportedly cause hereditary parkinsonism. To explore the roles of four paralogs (FBXO2, FBXO6, FBXO12, and FBXO41) in PD development, their variants (rs9614, rs28924120, rs6442117, and rs61733550, respectively) were analyzed in 502 Han Chinese patients with PD and 556 age, gender, and ethnicity-matched normal participants in mainland China. Statistically significant differences in genotypic and allelic frequencies were detected only in the FBXO2 variant rs9614 (P = 0.001 and 0.023, respectively; odds ratio 0.819, 95% confidence interval 0.690-0.973) between patients and controls. These results suggest that the FBXO2 variant rs9614 C allele may decrease the PD risk in mainland Han Chinese and may be a biomarker for PD.

Parkinson disease (PD; MIM 168600) is the second most common progressive neurodegenerative disorder characterized by a variety of motor and non-motor features. To date, at least 20 loci and 15 disease-causing genes for parkinsonism have been identified. Among them, the α-synuclein (SNCA) gene was associated with PARK1/PARK4. Point mutations, duplications and triplications in the SNCA gene cause a rare dominant form of PD in familial and sporadic PD cases. The α-synuclein protein, a member of the synuclein family, is abundantly expressed in the brain. The protein is the major component of Lewy bodies and Lewy neurites in dopaminergic neurons in PD. Further understanding of its role in the pathogenesis of PD through various genetic techniques and animal models will likely provide new insights into our understanding, therapy and prevention of PD.

Parkinson's disease (PD) is the second-most common etiologically complex neurodegenerative disease. Genetic abnormalities are thought to play an important role in the development of PD. Recently, mutations in the resistance to inhibitors of cholinesterase 3 gene (RIC3) have been reported to cause autosomal-dominant PD in Indian population. To determine whether RIC3 gene coding variant(s) are associated with PD in Han Chinese population, the RIC3 gene coding region in 218 mainland Han Chinese patients with PD and the identified variants in 242 normal controls were examined using direct sequencing analysis. Four known single nucleotide variants (c.354C>A, p.L118L, rs10839976; c.389G>A, p.C130Y, rs55990541; c.403C>T, p.P135S, rs73411617; and c.1054G>A, p.D352N, rs11826236) were identified in the RIC3 gene coding region. No significant differences were observed in either genotypic or allelic distributions between the PD patients and the normal controls (all P>0.05) for these four variants. Haplotype analysis showed that the presence of haplotype A-G-C-G (rs10839976-rs55990541-rs73411617-rs11826236) was associated with a 0.764-fold decreased risk (P=0.049, OR=0.764, 95% CI=0.585-0.999) for PD, whereas the presence of haplotype C-A-C-A was associated with a 2.143-fold increased risk (P=0.039, OR=2.143, 95% CI=1.023-4.488) for PD. The findings indicate that four variants: rs10839976, rs55990541, rs73411617 and rs11826236 in the RIC3 gene coding region may play little or no role in the development of PD. Two RIC3 gene haplotypes of four variants: A-G-C-G, and C-A-C-A might relate to either protection against or increased susceptibility to PD in the Han Chinese population, respectively.

Parkinson’s disease (PD) is one of the most common neurodegenerative disorders. Accumulated evidence confirms that genetic factors play a considerable role in PD pathogenesis. To examine whether point variants or haplotypes are associated with PD development, genotyping of 35 variants in 22 PD-related genes was performed in a well-characterized cohort of 512 Han Chinese PD patients and 512 normal controls. Both Pearson’s χ2 test and haplotype analysis were used to evaluate whether variants or their haplotypes were associated with PD in this cohort. The only statistically significant differences in genotypic and allelic frequencies between the patients and the controls were in the DnaJ heat shock protein family (Hsp40) member C10 gene (DNAJC10) variant rs13414223 (P = 0.004 and 0.002, respectively; odds ratio = 0.652, 95% confidence interval: 0.496–0.857). No other variants or haplotypes exhibited any significant differences between these two groups (all corrected P > 0.05). Our findings indicate that the variant rs13414223 in the DNAJC10 gene, a paralog of PD-related genes DNAJC6 and DNAJC13, may play a protective role in PD. This suggests it may be a PD-associated gene.

Camptodactyly is a digit deformity characterized by permanent flexion contracture of one or both fifth fingers at the proximal interphalangeal joints. Though over 60 distinct types of syndromic camptodactyly have been described, only one disease locus (3q11.2-q13.12) for nonsyndromic camptodactyly has been identified. To identify the genetic defect for camptodactyly in a four-generation Chinese Han family, exome and Sanger sequencings were conducted and a missense variant, c.1016C>T (p.S339L), in the talin 2 gene (TLN2) was identified. The variant co-segregated with disease in the family and was not observed in 12 unaffected family members or 1,000 normal controls, suggesting that p.S339L is a pathogenic mutation. Two asymptomatic carriers in the family indicated incomplete penetrance or more complicated compensated mechanism. Most of p.S339L carriers also have relatively benign cardiac phenotypes. Expression of wild and mutant TLN2 in HEK293 cells suggested the predominant localization in cytoplasm. Our data suggest a potential molecular link between TLN2 and camptodactyly pathogenesis.

Background A clinical overlap between essential tremor (ET) and Parkinson's disease (PD) has prompted investigation whether these disorders share common genetic factors. The paired-like homeodomain transcription factor 3 gene (PITX3) has been shown to play an important role for the differentiation and survival of midbrain dopaminergic neurons in the substantia nigra pars compacta. The preferential degeneration of those dopaminergic neurons is the pathological hallmark in PD. Aims of the study The purpose of this study was to evaluate whether PITX3 variants are related to susceptibility of ET in Chinese Han population. Methods Genetic analysis of two variants rs3758549 and rs4919621 of the PITX3 gene was conducted in 200 Chinese Han patients with ET and 426 controls. Results We did not identify any statistically significant difference in either genotypic or allelic frequencies of variants between the ET patients and control cohort (all P > 0.05). Haplotype analysis of two variants in the PITX3 gene showed no potential association between the haplotypes and risk of ET (all P > 0.05). Conclusions Our data suggest that PITX3 variants rs3758549 and rs4919621 are not associated with ET in Chinese Han population.

Osteopetrosis is a heritable bone condition featuring increased bone density due to defective osteoclastic bone resorption. Exome sequencing and Sanger sequencing were conducted in Han Chinese family members, some of whom had typical osteopetrosis, and a novel missense variant c.2350A>T (p.R784W) in the chloride channel 7 gene (CLCN7) was identified. This variant cosegregated with the disorder in the family but was not observed in 800 controls. The data indicate that exome sequencing is a powerful and effective molecular diagnostic tool for detecting mutations in osteopetrosis, which is a genetically and clinically heterogeneous disorder. This discovery broadens the CLCN7 gene mutation spectrum and has important implications for clinical therapeutic regimen decisions, prognosis evaluations, and antenatal diagnoses.

Autosomal recessive juvenile parkinsonism (AR-JP) is a distinct clinical and neuropathologic entity characterized by early onset parkinsonism and localized neuronal degeneration in the substantia nigra without Lewy bodies. The purpose of this study is to identify the genetic defect in a Chinese pedigree with familial AR-JP and to explore genotype-phenotype correlation. A three-generation Chinese Han pedigree with familial AR-JP was recruited in this study, and the patients in the pedigree presented with typical but heterogeneous clinical features of AR-JP and with different ages of disease onset. Exome sequencing and Sanger sequencing were conducted in the index case diagnosed as juvenile parkinsonism and a homozygous variant, c.850G > C (p.G284R), in the parkin gene was identified. The homozygous variant co-segregated with the disease in the family and was absent in 800 controls. The homozygous variant, c.850G > C (p.G284R), in the parkin gene is possibly responsible for AR-JP in this pedigree. Heterozygous c.850G > C mutation carriers were free of any neurological symptoms, consistent with a loss-of-function mechanism of the parkin mutations. These findings may provide new insights into the cause and diagnosis of AR-JP and have implications for genetic counseling.

This study demonstrates that the gap junction protein beta-2 gene (GJB2) p.R32C and p.L79Cfs*3 variants are associated to a consanguineous family with autosomal recessive non-syndromic hearing loss (ARNSHL). The p.R32C variant is found for the first time in the NSHL patients of Han Chinese origin. The finding sheds new light on the accurate genetic diagnosis and counseling for the family.ARNSHL is a highly heterogeneous genetic disease. ARNSHL usually displays non-progressive congenital or pre-lingual deafness. In this study, the aim is to detect the disease-causing mutation(s) in a Han family with ARNSHL.A consanguineous Han family with ARNSHL was enrolled. Two hundred ethnicity-matched unrelated subjects without any hearing impairments were used as normal controls. Exome sequencing and Sanger sequencing were applied to identify the causative mutation in the ARNSHL family.Compound heterozygous variants c.94C T (p.R32C) and c.235delC (p.L79Cfs*3) in the GJB2 gene were identified in the two patients of the ARNSHL family, and the heterozygous GJB2 c.94C T and c.235delC variants were identified in his unaffected father and mother, respectively. The two variants in the GJB2 gene were absent in the 200 unrelated controls.

Focal segmental glomerulosclerosis (FSGS) is the most common glomerular histological lesion associated with high‐grade proteinuria and end‐stage renal disease. Histologically, FSGS is characterized by focal segmental sclerosis with foot process effacement. The aim of this study was to identify the disease‐causing mutation in a four‐generation Chinese family with FSGS. A novel missense mutation, c.1856G>A (p.Gly619Asp), in the collagen type IV alpha‐4 gene (COL4A4) was identified in six patients and it co‐segregated with the disease in this family. The variant is predicted to be disease‐causing and results in collagen IV abnormalities. Our finding broadens mutation spectrum of the COL4A4 gene and extends the phenotypic spectrum of collagen IV nephropathies. Our study suggests that exome sequencing is a cost‐effective and efficient approach for identification of disease‐causing mutations in phenotypically complex or equivocal disorders. Timely screening for COL4A3/COL4A4 mutations in patients with familial FSGS may help both accurately diagnose and treat these patients.