Unaffected Members Research Articles

Uncovering the profile of mutations of transforming growth factor beta-induced gene in Chinese corneal dystrophy patients.

To uncover the mutations profile of transforming growth factor beta-induced (TGFBI) gene in Chinese corneal dystrophy patients and further investigate the characteristics of genotype-phenotype correlations. Forty-two subjects (6 unrelated families including 15 patients and 8 unaffected members, and 19 sporadic patients) of Chinese origin were subjected to phenotypic and genotypic characterization. The corneal phenotypes of patients were documented by slit lamp photography. Mutation screening of the coding regions of TGFBI was performed by direct sequencing. We detected four corneal dystrophy types. The most frequent phenotypes were granular corneal dystrophy (GCD) (including 3 families and 8 sporadic patients) and lattice corneal dystrophy (LCD) (including 2 families and 9 sporadic patients). The next phenotypes were corneal dystrophy of Bowman layer (CDB) (1 family and 1 sporadic patient) and epithelial basement membrane dystrophy (EBMD) (1 sporadic patient). Six distinct mutations responsible for TGFBI corneal dystrophies were identified in 30 individuals with corneal dystrophies. Those were, p.R124H mutation in 1 family and 2 sporadic patients with GCD, p.R555W mutation in 2 families and 3 sporadic patients with GCD, p.R124C mutation in 2 families and 7 sporadic patients with LCD, p.A620D mutation in 1 sporadic patient with LCD, p.H626R mutation in 1 sporadic patient with LCD, and p.R555Q in 1 family and 1 sporadic patient with CDB. No mutation was detected in the remaining 3 atypical GCD patients and 1 EBMD patient. GCD and LCD are the most frequent phenotypes in Chinese population. R555W was the most common mutation for GCD; R124C was the most common mutation for LCD. Our findings extend the mutational spectrum of TFGBI, and this is the extensively delineated TGFBI mutation profile associated with the various corneal dystrophies in the Chinese population.

A novel heterozygous missense mutation in the SASH1 gene is associated with dyschromatosis universalis hereditaria in a pedigree

Objective To investigate clinical features and molecular genetic basis of dyschromatosis universalis hereditaria (DUH) in a pedigree. Methods A detailed genetic survey and a physical examination were performed for available members in a pedigree with DUH. In addition, reflectance confocal microscopy and histopathology were carried out to observe skin lesions of the proband. Blood samples were collected from 8 family members (including 5 patients with DUH and 3 unaffected members) and 200 unrelated healthy human controls. The FlexiGene DNA kit was used to extract genomic DNA from these blood samples, and PCR was performed to amplify all coding exons and their flanking sequences of SASH1 and ABCB6 genes followed by direct DNA sequencing. Results DUH was inherited in an autosomal dominant manner in this pedigree, and occurred within 1 year after birth in 9 patients. Lesions initially appeared on the face, then gradually spread to the whole body. Among 8 surviving patients, 7 presented with irregularly shaped light brown to puce macules complicated by uniform hypopigmentation of the remaining skin, and only the elder sister of the proband showed generalized hyperpigmented macules mingled with hypopigmented macules in a reticular pattern. No abnormality was observed in oral mucosa, nails or teeth, and general status was good in the 8 patients. DNA sequencing revealed a novel heterozygous missense mutation (c.1761C > G, p.Ser587Arg) in exon 15 of the SASH1 gene in the 5 available patients, but not in the 3 unaffected individuals or 200 healthy controls. No mutation was found in the ABCB6 gene in any of the 8 family members. Conclusions Heterogeneity exists in clinical features and molecular genetic basis of DUH. The heterozygous missense mutation p.S587R in the SASH1 gene might be responsible for DUH in this family. Key words: Autosomal-dominant; Heterozygote; Mutation; Genetics; Han nationality; Genes, SASH1; Dyschromatosis universalis hereditaria

Knowledge and Uptake of Genetic Counseling and Colonoscopic Screening Among Individuals at Increased Risk for Lynch Syndrome and their Endoscopists from the Family Health Promotion Project.

Individuals whose families meet the Amsterdam II clinical criteria for hereditary non-polyposis colorectal cancer are recommended to be referred for genetic counseling and to have colonoscopic screening every 1-2 years. To assess the uptake and knowledge of guideline-based genetic counseling and colonoscopic screening in unaffected members of families who meet Amsterdam II criteria and their treating endoscopists. Participants in the Family Health Promotion Project who met the Amsterdam II criteria were surveyed regarding their knowledge of risk-appropriate guidelines for genetic counseling and colonoscopy screening. Endoscopy/pathology reports were obtained from patients screened during the study to determine the follow-up recommendations made by their endoscopists. Survey responses were compared using Fisher's Exact and the χ(2) test. Concordance in participant/provider-reported surveillance interval was assessed using the kappa statistic. Of the 165 participants, the majority (98%) agreed that genetics and family history are important predictors of CRC, and 63% had heard of genetic testing for CRC, although only 31% reported being advised to undergo genetic counseling by their doctor, and only 7% had undergone genetic testing. Only 26% of participants reported that they thought they should have colonoscopy every 1-2 years and 30% of endoscopists for these participants recommended 1-2-year follow-up colonoscopy. There was a 65% concordance (weighted kappa 0.42, 95% CI 0.24-0.61) between endoscopist recommendations and participant reports regarding screening intervals. A minority of individuals meeting Amsterdam II criteria in this series have had genetic testing and reported accurate knowledge of risk-appropriate screening, and only a small percentage of their endoscopists provided them with the appropriate screening recommendations. There was moderate concordance between endoscopist recommendations and participant knowledge suggesting that future educational interventions need to target both health-care providers and their patients.

Clinical features and gene mutation analysis of cartilage oligomeric matrix protein in a family with pseudoachondroplasia

Objective To investigate cartilage oligomeric matrix protein(COMP)gene mutation in a three-generation pedigree with two cases of pseudoachondroplasia, and to definitize genotype-phenotype correlation. Methods The clinical data and peripheral blood were collected from the patients with pseudoachondroplasia and their family members. All the 19 exons and their flanking sequences of COMP gene in two patients and three unaffected family numbers and 50 unrelated individuals were analyzed by PCR amplification and direct sequencing. Results The proband, a 6-year-old girl presented with typical clinical features of pseudoachondroplasia, including disproportionate short limb dwarfism, staggering gait, double genu varus deformity, and wider clinical and imaging long bone metaphysis. The 33-year-old father showed a similar manifestation including disproportionate short limb dwarfism and double genu varus deformity, and was performed correcting operation on lower limbs for double genu varus at the age of 10 years. DNA sequencing analysis of the COMP gene revealed a del mutation(c.1417_1419delGAC)in exon 13 in two patients with pseudoachondroplasia, but not in the other unaffected members from the pedrgree and 50 control subjects. Conclusion A del mutation c. 1417_1419delGAC of COMP gene may contribute to the disease in the pedigree. Key words: Pseudoachondroplasia; Cartilage oligomeric matrix protein; Gene mutation

Increased expression of the PI3K catalytic subunit p110δ underlies elevated S6 phosphorylation and protein synthesis in an individual with autism from a multiplex family.

BackgroundDysfunctions in the PI3K/mTOR pathway have gained a lot of attention in autism research. This was initially based on the discovery of several monogenic autism spectrum disorders with mutations or defects in PI3K/mTOR signaling components. Recent genetic studies corroborate that defective PI3K/mTOR signaling might be a shared pathomechanism in autism disorders of so far unknown etiology, but functional molecular analyses in human cells are rare. The goals of this study were to perform a functional screen of cell lines from patients with idiopathic autism for defects in PI3K/mTOR signaling, to test if further functional analyses are suitable to detect underlying molecular mechanisms, and to evaluate this approach as a biomarker tool to identify therapeutic targets.MethodsWe performed phospho-S6- and S6-specific ELISA experiments on 21 lymphoblastoid cell lines from the AGRE collection and on 37 lymphoblastoid cell lines from the Simons Simplex Collection and their healthy siblings. Cell lines from one individual with increased S6 phosphorylation and his multiplex family were analyzed in further detail to identify upstream defects in PI3K signaling associated with autism diagnosis.ResultsWe detected significantly increased S6 phosphorylation in 3 of the 21 lymphoblastoid cell lines from AGRE compared to a healthy control and in 1 of the 37 lymphoblastoid cell lines from the Simons Simplex Collection compared to the healthy sibling. Further analysis of cells from one individual with elevated S6 phosphorylation showed increased expression of the PI3K catalytic subunit p110δ, which was also observed in lymphoblastoid cells from other autistic siblings but not unaffected members in his multiplex family. The p110δ-selective inhibitor IC87114 reduced elevated S6 phosphorylation and protein synthesis in this cell line.ConclusionsOur results suggest that functional analysis of PI3K/mTOR signaling is a biomarker tool to identify disease-associated molecular defects that could serve as therapeutic targets in autism. Using this approach, we discovered impaired signaling and protein synthesis through the PI3K catalytic subunit p110δ as an underlying molecular defect and potential treatment target in select autism spectrum disorders. Increased p110δ activity was recently associated with schizophrenia, and our results suggest that p110δ may also be implicated in autism.Electronic supplementary materialThe online version of this article (doi:10.1186/s13229-015-0066-4) contains supplementary material, which is available to authorized users.

A novel splice donor site mutation in EPHA2 caused congenital cataract in a Chinese family.

Background:Congenital cataract is a rare disorder characterized by crystallin denaturation, which becomes a major cause of childhood blindness. Although more than fifty pathogenic genes for congenital cataract have been reported, the genetic causes of many cataract patients remain unknown. In this study, the aim is to identify the genetic cause of a five-generation Chinese autosomal dominant congenital cataract family.Methods:Whole exome sequencing (WES) was performed on three affected and one unaffected member of the family, known causative genes were scanned first. Sanger sequencing was used to validate co-segregation of the candidate variant in the family. The impact on the transcript and amino acid sequences of the variant was further analyzed.Results:We identified a novel splice donor site mutation c. 2825+1G >A in EPHA2 that was absent in public and in-house databases and showed co-segregation in the family. This variant resulted in an altered splice that led to protein truncation.Conclusions:The mutation we identified was responsible for congenital cataract in our studied family. Our findings broaden the spectrum of causative mutations in EPHA2 gene for congenital cataract and suggest that WES is an efficient strategy to scan variants in known causative genes for genetically heterogeneous diseases.

A novel CRX mutation by whole-exome sequencing in an autosomal dominant cone-rod dystrophy pedigree.

To identify the disease-causing gene mutation in a Chinese pedigree with autosomal dominant cone-rod dystrophy (adCORD). A southern Chinese adCORD pedigree including 9 affected individuals was studied. Whole-exome sequencing (WES), coupling the Agilent whole-exome capture system to the Illumina HiSeq 2000 DNA sequencing platform was used to search the specific gene mutation in 3 affected family members and 1 unaffected member. After a suggested variant was found through the data analysis, the putative mutation was validated by Sanger DNA sequencing of samples from all available family members. The results of both WES and Sanger sequencing revealed a novel nonsense mutation c.C766T (p.Q256X) within exon 5 of CRX gene which was pathogenic for adCORD in this family. The mutation could affect photoreceptor-specific gene expression with a dominant-negative effect and resulted in loss of the OTX tail, thus the mutant protein occupies the CRX-binding site in target promoters without establishing an interaction and, consequently, may block transactivation. All modes of Mendelian inheritance in CORD have been observed, and genetic heterogeneity is a hallmark of CORD. Therefore, conventional genetic diagnosis of CORD would be time-consuming and labor-intensive. Our study indicated the robustness and cost-effectiveness of WES in the genetic diagnosis of CORD.

A novel missense mutation in cathepsin K (CTSK) gene in a consanguineous Pakistani family with pycnodysostosis.

Deficiency of cathepsin K (CTSK), a lysosomal cysteine protease, has been shown earlier as a cause of an autosomal recessive osteosclerotic skeletal dysplasia pycnodysostosis. The objective of the present study was to identify the potential sequence variants in CTSK gene in a large consanguineous Pakistani family with pycnodysostosis. Genotyping of 4 affected and 6 unaffected members of the family was performed using polymorphic microsatellite markers linked to CTSK gene on chromosome 1q21. To screen for pathogenic mutation, exons and splice junctions of CTSK gene were polymerase chain reaction amplified from genomic DNA and sequenced directly in an automated DNA sequencer. Microsatellite analysis showed linkage of the family to CTSK gene on chromosome 1q21. Sequence analysis revealed a novel missense mutation c.728G>A (p.G243E) in exon 6 of the CTSK gene. A novel missense mutation was identified in CTSK gene in a Pakistani family with 5 individuals affected with autosomal recessive pycnodysostosis.

North Carolina Macular Dystrophy Is Caused by Dysregulation of the Retinal Transcription Factor PRDM13

To identify specific mutations causing North Carolina macular dystrophy (NCMD). Whole-genome sequencing coupled with reverse transcription polymerase chain reaction (RT-PCR) analysis of gene expression in human retinal cells. A total of 141 members of 12 families with NCMD and 261 unrelated control individuals. Genome sequencing was performed on 8 affected individuals from 3 families affected with chromosome 6-linked NCMD (MCDR1) and 2 individuals affected with chromosome 5-linked NCMD (MCDR3). Variants observed in the MCDR1 locus with frequencies <1% in published databases were confirmed using Sanger sequencing. Confirmed variants absent from all published databases were sought in 8 additional MCDR1 families and 261 controls. The RT-PCR analysis of selected genes was performed in stem cell-derived human retinal cells. Co-segregation of rare genetic variants with disease phenotype. Five sequenced individuals with MCDR1-linked NCMD shared a haplotype of 14 rare variants spanning 1 Mb of the disease-causing allele. One of these variants (V1) was absent from all published databases and all 261 controls, but was found in 5 additional NCMD kindreds. This variant lies in a DNase 1 hypersensitivity site (DHS) upstream of both the PRDM13 and CCNC genes. Sanger sequencing of 1 kb centered on V1 was performed in the remaining 4 NCMD probands, and 2 additional novel single nucleotide variants (V2 in 3 families and V3 in 1 family) were identified in the DHS within 134 bp of the location of V1. A complete duplication of the PRDM13 gene was also discovered in a single family (V4). The RT-PCR analysis of PRDM13 expression in developing retinal cells revealed marked developmental regulation. Next-generation sequencing of 2 individuals with MCDR3-linked NCMD revealed a 900-kb duplication that included the entire IRX1 gene (V5). The 5 mutations V1 to V5 segregated perfectly in the 102 affected and 39 unaffected members of the 12 NCMD families. We identified 5 rare mutations, each capable of arresting human macular development. Four of these strongly implicate the involvement of PRDM13 in macular development, whereas the pathophysiologic mechanism of the fifth remains unknown but may involve the developmental dysregulation of IRX1.

Cancer Worry, Perceived Risk and Cancer Screening in First‐Degree Relatives of Patients with Familial Gastric Cancer

Currently, there is a lack of evidence evaluating the psychological impact of cancer-related risk perception and worry in individuals at high risk for gastric cancer. We examined the relationships between perceived risk, cancer worry and screening behaviors among first-degree relatives (FDRs) of patients with familial gastric cancer. FDRs of patients diagnosed with familial gastric cancer with a non-informative genetic analysis were identified and contacted. Participants completed a telephone interview that assessed socio-demographic information, cancer risk perception, cancer worry, impact of worry on daily functioning, and screening behaviors. Twenty-five FDRs completed the telephone interview. Participants reported high levels of comparative and absolute cancer risk perception, with an average perceived lifetime risk of 54%. On the other hand, cancer-related worry scores were low, with a significant minority (12%) experiencing high levels of worry. Study participants exhibited high levels of confidence (median=70%) in the effectiveness of screening at detecting a curable cancer. Participants that had undergone screening in the past showed significantly lower levels of cancer-related worry compared to those that had never undergone screening. In conclusion, individuals at high-risk for gastric cancer perceived a very high personal risk of cancer, but reported low levels of cancer worry. This paradoxical result may be attributed to participants' high levels of confidence in the effectiveness of screening. These findings highlight the importance for clinicians to discuss realistic risk appraisals and expectations towards screening with unaffected members of families at risk for gastric cancer, in an effort to help mitigate anxiety and help with coping.

A novel phenotype-genotype correlation with an Arg555Trp mutation of TGFBI gene in Thiel-Behnke corneal dystrophy in a Chinese pedigree.

BackgroundTo investigate the molecular defects in a four-generation Chinese pedigree affected with Thiel-Behnke corneal dystrophy (TBCD). And to further study the relationship between genetic mutation and clinical manifestations.MethodsIndividuals of the pedigree were recruited for extensive ophthalmic examinations. Histological studies of two corneal buttons obtained from lamellar keratoplasty were conducted. Peripheral blood was collected in EDTA for genomic DNA isolation from leukocytes of all affected and unaffected members. All 17 exons of the TGFBI gene were screened for mutations by polymerase chain reaction and direct DNA sequencing.ResultsClinical examinations revealed a typical pattern of honeycomb-like TBCD. Histopathology study demonstrated eosinophilic deposits that were congo-red-positive and did not stain with periodic acid Schiff or Masson’s trichrome. Genetic analysis disclosed a heterozygous p. Arg555Trp mutation resulted from a missense c. 1663C > T nucleotide change in exon 12 of TGFBI gene in all affected members. Morever, a second rare variant in exon 6 of the TGFBI gene (p. Arg257Trp) also cosegregated within this family and has been confirmed to be a single nucleotide polymorphism (SNP) not previously reported.ConclusionsThe p. Arg555Trp mutation of the TGFBI gene was associated with TBCD, which revealed a novel phenotype-genotype correlation within the mutational spectrum of phenotypically diverse corneal dystrophies.

Variants in the genes DCTN2, DNAH10, LRIG3, and MYO1A are associated with intermediate Charcot-Marie-Tooth disease in a Norwegian family.

IntroductionCharcot–Marie–Tooth disease (CMT) is a heterogeneous inherited neuropathy. The number of known CMT genes is rapidly increasing mainly due to next‐generation sequencing technology, at present more than 70 CMT‐associated genes are known. We investigated whether variants in the DCTN2 could cause CMT.Material and methodsFifty‐nine Norwegian CMT families from the general population with unknown genotype were tested by targeted next‐generation sequencing (NGS) for variants in DCTN2 along with 32 CMT genes and 19 other genes causing other inherited neuropathies or neuronopathies, due to phenotypic overlap. In the family with the DCTN2 variant, exome sequencing was then carried out on all available eight family members to rule out the presence of more potential variants.ResultsTargeted NGS identified in one family a variant of DCTN2, c.337C>T, segregating with the phenotype in five affected members, while it was not present in the three unaffected members. The DCTN2 variant c.337C>T; p.(His113Tyr) was neither found in in‐house controls nor in SNP databases. Exome sequencing revealed a singular heterozygous shared haplotype containing four genes, DCTN2,DNAH10,LRIG3, and MYO1A, with novel sequence variants. The haplotype was shared by all the affected members, while the unaffected members did not have it.ConclusionsThis is the first time a haplotype on chromosome 12 containing sequence variants in the genes DCTN2,DNAH10,LRIG3, and MYO1A has been linked to an inherited neuropathy in humans.

First Identification of Compound Heterozygous FKRP Mutations in a Korean Patient with Limb-Girdle Muscular Dystrophy.

Dystroglycanopathies are a genetically and clinically heterogeneous group of muscular dystrophies that are characterized by reduced glycosylation of α-dystroglycan. Among 18 causative genes, the fukutin-related protein (FKRP; MIM 606596) gene is the most common cause in Caucasians.1 However, FKRP mutations have rarely been found in the Asian population,2 and have not been reported previously in Korea. Herein we report novel compound FKRP mutations in a patient with myopathy, which represents the first reported case in Korea. A 43-year-old female (II-4) (Fig. 1A) was the fourth child of nonconsanguineous healthy Korean parents who achieved normal motor milestones after birth. She first noticed difficulty in climbing stairs at age 7 years, but muscle weakness did not progress. At the age of 23 years the patient perceived the progression of muscle weakness and was admitted to our institute. She displayed proximal weakness, especially in the pelvic girdle muscles. Mild winged scapulae and lordosis were also observed. No sensory deficits, joint contracture, tongue hypertrophy, or mental retardation were apparent. Her serum creatine kinase level was markedly elevated, at 2,439 IU/L (reference value: <185 IU/L). An electrophysiological study revealed a generalized myogenic process. No cardiac abnormality was observed. At the last examination, when she was 43 years old, she could walk with assistance. Fig. 1 Pedigree, sequencing chromatograms, and conservation profile of the patient. A: Pedigree of a Korean patient with compound heterozygous FKRP mutations. The filled symbol indicates the affected member; open symbols indicate unaffected members. B: Sequencing ... The genetic cause of this patient's myopathy was evaluated by performing targeted sequencing of 69 myopathy-causative genes including FKRP (Supplementary Information, Supplementary Table 1, 2, and 3 in the online-only Data Supplement). DNA fragments in the target regions were enriched by solution-based hybridization capture, followed by sequencing with an Illumina Hiseq2000 platform. The sequencing data were analyzed using a standard pipeline. Variants were then filtered further based on the patient's phenotype. Compound heterozygous FKRP mutations of c.857G>C and c.1170_1171delGC were identified (Fig. 1B). The c.1170_1171delGC mutation has been reported previously in a Japanese patient with congenital muscular dystrophy.2 However, the c.857G>C mutation was novel, and was not detected in 352 healthy controls, dbSNP138, or the 1000 Genomes Database (September 2014 release). In silico analysis using SIFT and PolyPhen2 predicted this mutation to be disease-causing. Genomic evolutionary rate profiling (GERP) indicated that the affected nucleotide is highly conserved (score=4.16), as became apparent upon inspection of the amino acid sequence in the altered region of the protein (Fig. 1C). Thus, the compound heterozygous FKRP mutations of c.1170_1171delGC and c.857G>C were determined to be the underlying cause of the myopathy in this patient. FKRP mutations result in various clinical presentations from severe brain abnormality to mild limb-girdle muscular dystrophy.1 This variability makes it difficult to diagnose FKRP-related muscular dystrophy based on clinical findings alone. Therefore, a step-by-step, classical approach with assessment of muscle pathology, muscle immunoanalysis, and mutational analysis is needed for the diagnosis of FKRP-related muscular dystrophy. The findings of a recent study in Taiwan that employed this approach suggested that FKRP-related muscular dystrophy is underdiagnosed, and not rare in the Asian population.3 However, this classical approach often fails to identify the causative gene due to pathological variability and the limited power of muscle immunoanalysis. Advances in next-generation sequencing, including targeted sequencing, have enabled the rapid and cost-effective analysis of many causative genes in uncategorized muscular dystrophy.4 In the present case, compound heterozygous FKRP mutations were identified using such next-generation sequencing. In conclusion, novel compound heterozygous FKRP mutations were identified in a patient with limb-girdle muscular dystrophy; this is the first reported case in Korea.

Phenotype of Usher syndrome type II assosiated with compound missense mutations of c.721 C>T and c.1969 C>T in MYO7A in a Chinese Usher syndrome family.

To identify the pathogenic mutations in a Chinese pedigree affected with Usher syndrome type II (USH2). The ophthalmic examinations and audiometric tests were performed to ascertain the phenotype of the family. To detect the genetic defect, exons of 103 known RDs -associated genes including 12 Usher syndrome (USH) genes of the proband were captured and sequencing analysis was performed to exclude known genetic defects and find potential pathogenic mutations. Subsequently, candidate mutations were validated in his pedigree and 100 normal controls using polymerase chain reaction (PCR) and Sanger sequencing. The patient in the family occurred hearing loss (HL) and retinitis pigmentosa (RP) without vestibular dysfunction, which were consistent with standards of classification for USH2. He carried the compound heterozygous mutations, c.721 C>T and c.1969 C>T, in the MYO7A gene and the unaffected members carried only one of the two mutations. The mutations were not present in the 100 normal controls. We suggested that the compound heterozygous mutations of the MYO7A could lead to USH2, which had revealed distinguished clinical phenotypes associated with MYO7A and expanded the spectrum of clinical phenotypes of the MYO7A mutations.

A recurrent mutation of CRYGD gene in a northern Chinese family with autosomal dominant congenital nuclear cataract

Background Congenital cataract is a major cause for blindness of childhood. Genetic gene mutation accounts for almost 1/3 of congenital cataract patients. The most common inheritance type is autosomal dominant congenital cataract (ADCC). Over 100 mutations in 26 genes have been found to be associated with ADCC. Objective This study was to identify the disease-causing gene mutation in a family with ADCC. Methods This study was approved by Ethic Committee of Beijing Tongren Hospital and followed Declaration of Helsinki. A northern Chinese family with autosomal dominant congenital nuclear cataract was entrolled in Beijing Tongren Hospital in January 2011. Ocular examinations were performed and periphery blood specimens were collected from each family member under the informed consent. Genomic DNA was extracted. Twenty-one microsatellite markers around 17 ADCC genes were selected for linkage analysis, and two-point LOD score was calculated. CRYGC gene and CRYGD gene were amplified and screened for mutations using direct sequencing. ProtScale software was used to analyze the changes of hydrophobicity of the mutated protein. Co-segregation of the observed change with the disease phenotype was further detected by restriction fragment length polymorphism (RFLP). Results This family included 20 members of 4 generations, and 9 patients were examined in serial 4 passages, which conformed to autosomal dominant inheritance pattern. Clinical examination revealed binocular congenital nuclear cataract in the 9 patients. Maximum two-point LOD score was 4. 68 at marker D2S325 (θ=0). A known T→C change at position 127 of cDNA sequence was found by mutations screening of CRYGD gene. ProtScale programs showed an obvious increase of the local hydrophobicity in the mutant protein. RFLP results indicated that this missense mutation co-segregated with affected members of the family, but was absent in unaffected members and 100 unrelated controls. Conclusions c. T127C mutation of CRYGD gene appears to be the molecular pathogenesis of this ADCC family. Aberrant structure of mutant CRYGD protein caused by hydrophobicity change may lead to opacification of lens. Key words: Cataract/congenital; Cataract/genetics; DNA mutational analysis; Lens nucleus, crystalline/pathology; Pedigree; gamma-Crystallin/genetics; Mutations; Chinese

Mutation analysis of HOXD13 gene in a Chinese family affected with autosomal dominant synpolydactyly

To detect potential mutation in a Chinese family affected with autosomal-dominant synpolydactyly and to provide the basis for prenatal diagnosis. Inheritance pattern was determined by clinical examination and pedigree analysis. Blood samples were obtained from members of the family. Genomic DNA was extracted and sequenced following PCR amplification. Suspected mutation was confirmed by subclone sequencing and agarose gel electrophoresis. A 27 bp expansion mutation in exon 1 of HOXD13 was identified in all affected individuals from the family but not in unaffected members and normal controls. The mutation has caused insertion of 9 alanines in the polyalanine-expansion region of HOXD13 protein. A polyalanine-expansion within the HOXD13 probably underlies the disease in this family.

Germline mutations causing familial lung cancer.

Genetic factors are important in lung cancer, but as most lung cancers are sporadic, little is known about inherited genetic factors. We identified a three-generation family with suspected autosomal dominant inherited lung cancer susceptibility. Sixteen individuals in the family had lung cancer. To identify the gene(s) that cause lung cancer in this pedigree, we extracted DNA from the peripheral blood of three individuals and from the blood of one cancer-free control family member and performed whole-exome sequencing. We identified 41 alterations in 40 genes in all affected family members but not in the unaffected member. These were considered candidate mutations for familial lung cancer. Next, to identify somatic mutations and/or inherited alterations in these 40 genes among sporadic lung cancers, we performed exon target enrichment sequencing using 192 samples from sporadic lung cancer patients. We detected somatic 'candidate' mutations in multiple sporadic lung cancer samples; MAST1, CENPE, CACNB2 and LCT were the most promising candidate genes. In addition, the MAST1 gene was located in a putative cancer-linked locus in the pedigree. Our data suggest that several genes act as oncogenic drivers in this family, and that MAST1 is most likely to cause lung cancer.

New Insights into Genotype-phenotype Correlations in Chinese Facioscapulohumeral Muscular Dystrophy: A Retrospective Analysis of 178 Patients.

Background:Facioscapulohumeral muscular dystrophy (FSHD), a common autosomal dominant muscular disorder, is caused by contraction of the D4Z4 repeats on 4q35. The complicated genotype-phenotype correlation among different ethnic population remains a controversial subject. We aimed to refine this correlation in order to provide new information for genetic counseling.Methods:Here, a cohort of 136 Chinese families including 178 affected individuals and 137 unaffected members were investigated. Genetic analyses were performed using the p13E-11, 4qA and 4qB probes after pulsed field gel electrophoresis separation and southern blotting. A 10-grade FSHD clinical severity scale was adopted for clinical assessment. The genotype-phenotype correlation was established by linear regression analyses.Results:We observed a roughly inversed correlation between the short EcoRI fragment size and age-corrected clinical severity score in 154 symptomatic patients (P < 0.05). Compared to male patients, a significant higher proportion of females in both asymptomatic carriers and severe patients showed larger variation in the size of short EcoRI fragment. A high incidence (19/42, 45.2%) of asymptomatic (or minimally affected) carriers was found in familial members.Conclusions:Although the number of D4Z4 repeats is known as one of the critical influences on genotype-phenotype correlation, a majority of phenotypic spectrum was still incompatible with their heterozygous contraction of the D4Z4 repeat, especial in female cases. Our results suggest that there are multi-factors synergistically modulating the phenotypic expression.

Novel genes and variants associated with IgA nephropathy by co-segregating with the disease phenotypes in 10 IgAN families

BackgroundPreviously, a large proportion of the genetic components predisposing individuals to IgA nephropathy (IgAN) have been unidentified. Familial IgAN is enriched with genetic variations predisposing individuals to the disease. Whole exome sequencing is an effective way to explore disease-causing genes and gene variants. MethodsWe performed exome sequencing on the probands from each of ten IgAN families, and on one of the unaffected member from 7 of the families. Sanger sequencing, bioinformatics and co-segregation analysis were performed for all available family members to detect deleterious genetic variation. The relatedness of the families was tested by haplotype analyses. ResultsSix deleterious variants in 4 genes were observed to be associated with IgA nephropathy by co-segregating with the disease phenotypes in study families. MYCT1 p.Asp22Glufs*34 was associated with IgAN by co-segregating with its phenotypes in families 2, 7, and 9; DEFA4 p.Ala8Pro, p.Ala8Val, c.172+1G>T co-segregated in families 1, 2, and 3; ZNF543 p.Pro226Ala co-segregated in families 3, 5, and 6 and CARD8 p.Val98Lysfs*26 co-segregated in families 7 and 8. Among these genes, MYCT1, CARD8 and ZNF543 are novel. Our haplotype analyses showed that families in which the same variation(s) were co-segregating with IgAN were unrelated, except for DEFA4. Of the families carrying DEFA4, families 2 and 3 were possibly related, but not family 1, indicating that common genes/variations in these families were not due to the same founder. Interfamilial sharing of different co-segregating genes was also observed, demonstrating the polygenic nature of this disease. ConclusionsWe discovered 6 deleterious variants in 4 genes associated with familial IgAN. These genes are good candidate genes that appear to be causally related to IgAN and warrant further study.

Detection of ADAR1 gene mutation in a family with dyschromatosis symmetrica hereditaria

To detect mutation of ADAR1 gene in a family affected with dyschromatosis symmetrica hereditaria. Clinical data and blood samples of the family were collected. Potential mutation of the ADAR1 gene were scanned in 3 patients and 3 unaffected members by PCR amplification and direct sequencing. The coding sequences of the ADAR1 were also screened in 50 normal controls. A frameshift mutation (c.2252insG) of the ADAR1 gene was identified in all of the 3 patients. The same mutation was not found in the 3 unaffected members and 50 normal cases. The frameshift mutation of ADAR1 gene (c.2252insG) is probably responsible for the disease in this family.