Expansion of Human-Specific GGC Repeat in Neuronal Intranuclear Inclusion Disease-Related Disorders.

Neuronal intranuclear inclusion disease (NIID) is a slowly progressing neurodegenerative disease characterized by eosinophilic intranuclear inclusions in the nervous system and multiple visceral organs. The clinical manifestation of NIID varies widely, and both familial and sporadic cases have been reported. Here we have performed genetic linkage analysis and mapped the disease locus to 1p13.3-q23.1; however, whole-exome sequencing revealed no potential disease-causing mutations. We then performed long-read genome sequencing and identified a large GGC repeat expansion within human-specific NOTCH2NLC. Expanded GGC repeats as the cause of NIID was further confirmed in an additional three NIID-affected families as well as five sporadic NIID-affected case subjects. Moreover, given the clinical heterogeneity of NIID, we examined the size of the GGC repeat among 456 families with a variety of neurological conditions with the known pathogenic genes excluded. Surprisingly, GGC repeat expansion was observed in two Alzheimer disease (AD)-affected families and three parkinsonism-affected families, implicating that the GGC repeat expansions in NOTCH2NLC could also contribute to the pathogenesis of both AD and PD. Therefore, we suggest defining a term NIID-related disorders (NIIDRD), which will include NIID and other related neurodegenerative diseases caused by the expanded GGC repeat within human-specific NOTCH2NLC.

Identification of the Largest SCA36 Pedigree in Asia: with Multimodel Neuroimaging Evaluation for the First Time.

Spinocerebellar ataxias (SCAs) are a large group of hereditary neurodegenerative diseases characterized by ataxia and dysarthria. Due to high clinical and genetic heterogeneity, many SCA families are undiagnosed. Herein, using linkage analysis, WES, and RP-PCR, we identified the largest SCA36 pedigree in Asia. This pedigree showed some distinct clinical characteristics. Cognitive impairment and gaze palsy are common and severe in SCA36 patients, especially long-course patients. Although no patients complained of hearing loss, most of them presented with hearing impairment in objective auxiliary examination. Voxel-based morphometry (VBM) demonstrated a reduction of volumes in cerebellum, brainstem, and thalamus (corrected P < 0.05). Reduced volumes in cerebellum were also found in presymptomatic carriers. Resting-state functional MRI (R-fMRI) found reduced ReHo values in left cerebellar posterior lobule (corrected P < 0.05). Diffusion tensor imaging (DTI) demonstrated a reduction of FA values in cerebellum, midbrain, superior and inferior cerebellar peduncle (corrected P < 0.05). MRS found reduced NAA/Cr values in cerebellar vermis and hemisphere (corrected P < 0.05). Our findings could provide new insights into management of SCA36 patients. Detailed auxiliary examination are recommended to assess hearing or peripheral nerve impairment, and we should pay more attention to eye movement and cognitive changes in patients. Furthermore, for the first time, our multimodel neuroimaging evaluation generate a full perspective of brain function and structure in SCA36 patients.

Expansion of GGC repeat in the human-specific NOTCH2NLC gene is associated with essential tremor.

Essential tremor is one of the most common movement disorders. Despite its high prevalence and heritability, the genetic aetiology of essential tremor remains elusive. Up to now, only a few genes/loci have been identified, but these genes have not been replicated in other essential tremor families or cohorts. Here we report a genetic study in a cohort of 197 Chinese pedigrees clinically diagnosed with essential tremor. Using a comprehensive strategy combining linkage analysis, whole-exome sequencing, long-read whole-genome sequencing, repeat-primed polymerase chain reaction and GC-rich polymerase chain reaction, we identified an abnormal GGC repeat expansion in the 5' region of the NOTCH2NLC gene that co-segregated with disease in 11 essential tremor families (5.58%) from our cohort. Clinically, probands that had an abnormal GGC repeat expansion were found to have more severe tremor phenotypes, lower activities of daily living ability. Obvious genetic anticipation was also detected in these 11 essential tremor-positive families. These results indicate that abnormal GGC repeat expansion in the 5' region of NOTCH2NLC gene is associated with essential tremor, and provide strong evidence that essential tremor is a family of diseases with high clinical and genetic heterogeneities.

Coding mutations in NUS1 contribute to Parkinson's disease.

Whole-exome sequencing has been successful in identifying genetic factors contributing to familial or sporadic Parkinson's disease (PD). However, this approach has not been applied to explore the impact of de novo mutations on PD pathogenesis. Here, we sequenced the exomes of 39 early onset patients, their parents, and 20 unaffected siblings to investigate the effects of de novo mutations on PD. We identified 12 genes with de novo mutations (MAD1L1, NUP98, PPP2CB, PKMYT1, TRIM24, CEP131, CTTNBP2, NUS1, SMPD3, MGRN1, IFI35, and RUSC2), which could be functionally relevant to PD pathogenesis. Further analyses of two independent case-control cohorts (1,852 patients and 1,565 controls in one cohort and 3,237 patients and 2,858 controls in the other) revealed that NUS1 harbors significantly more rare nonsynonymous variants (P = 1.01E-5, odds ratio = 11.3) in PD patients than in controls. Functional studies in Drosophila demonstrated that the loss of NUS1 could reduce the climbing ability, dopamine level, and number of dopaminergic neurons in 30-day-old flies and could induce apoptosis in fly brain. Together, our data suggest that de novo mutations could contribute to early onset PD pathogenesis and identify NUS1 as a candidate gene for PD.

Familial paroxysmal kinesigenic dyskinesia is associated with mutations in the KCNA1 gene.

Paroxysmal kinesigenic dyskinesia (PKD) is a heterogeneous movement disorder characterized by recurrent dyskinesia attacks triggered by sudden movement. PRRT2 has been identified as the first causative gene of PKD. However, it is only responsible for approximately half of affected individuals, indicating that other loci are most likely involved in the etiology of this disorder. To explore the underlying causative gene of PRRT2-negative PKD, we used a combination strategy including linkage analysis, whole-exome sequencing and copy number variations analysis to detect the genetic variants within a family with PKD. We identified a linkage locus on chromosome 12 (12p13.32-12p12.3) and detected a novel heterozygous mutation c.956 T>G (p.319 L>R) in the potassium voltage-gated channel subfamily A member 1, KCNA1. Whole-exome sequencing in another 58 Chinese patients with PKD who lacked mutations in PRRT2 revealed another novel mutation in the KCNA1 gene [c.765 C>A (p.255 N>K)] within another family. Biochemical analysis revealed that the L319R mutant accelerated protein degradation via the proteasome pathway and disrupted membrane expression of the Kv1.1 channel. Electrophysiological examinations in transfected HEK293 cells showed that both the L319R and N255K mutants resulted in reduced potassium currents and respective altered gating properties, with a dominant negative effect on the Kv1.1 wild-type channel. Our study suggests that these mutations in KCNA1 cause the Kv1.1 channel dysfunction, which leads to familial PKD. The current study further extended the genotypic spectrum of this disorder, indicating that Kv1.1 channel dysfunction maybe one of the underlying defects in PKD.

Long-read sequencing identified intronic repeat expansions in SAMD12 from Chinese pedigrees affected with familial cortical myoclonic tremor with epilepsy.

BACKGROUND: The locus for familial cortical myoclonic tremor with epilepsy (FCMTE) has long been mapped to 8q24 in linkage studies, but the causative mutations remain unclear. Recently, expansions of intronic TTTCA and TTTTA repeat motifs within SAMD12 were found to be involved in the pathogenesis of FCMTE in Japanese pedigrees. We aim to identify the causative mutations of FCMTE in Chinese pedigrees. METHODS: We performed genetic linkage analysis by microsatellite markers in a five-generation Chinese pedigree with 55 members. We also used array-comparative genomic hybridisation (CGH) and next-generation sequencing (NGS) technologies (whole-exome sequencing, capture region deep sequencing and whole-genome sequencing) to identify the causative mutations in the disease locus. Recently, we used low-coverage (~10×) long-read genome sequencing (LRS) on the PacBio Sequel and Oxford Nanopore platforms to identify the causative mutations, and used repeat-primed PCR for validation of the repeat expansions. RESULTS: Linkage analysis mapped the disease locus to 8q23.3-24.23. Array-CGH and NGS failed to identify causative mutations in this locus. LRS identified the intronic TTTCA and TTTTA repeat expansions in SAMD12 as the causative mutations, thus corroborating the recently published results in Japanese pedigrees. CONCLUSIONS: We identified the pentanucleotide repeat expansion in SAMD12 as the causative mutation in Chinese FCMTE pedigrees. Our study also suggested that LRS is an effective tool for molecular diagnosis of genetic disorders, especially for neurological diseases that cannot be positively diagnosed by conventional clinical microarray and NGS technologies.

Exome sequencing identifies POU4F3 as the causative gene for a large Chinese family with non-syndromic hearing loss.

Hearing impairment, or deafness (in its most severe form), is one of the most common human sensory disorders. There have been several reports of autosomal dominant mutations in the POU4F3 gene, which is associated with non-syndromic hearing loss. In this study, we identified a novel heterozygous mutation (c.602delT, p.L201fs) in the gene POU4F3 by taking advantage of whole-exome sequencing, which was validated by Sanger sequencing and completely co-segregated within a large hearing impaired Chinese family. We have focused on this pedigree since 2002, and we have mapped a deafness locus named DFNA42 (which has been renamed DFNA52, OMIM entry 607683) via a genome-wide scan. Furthermore, we analyzed this mutational variant and found that it was located at the beginning of the first functional domain of POU4F3, which could theoretically impair the function of POU4F3. We have identified a novel frameshift mutation in the POU4F3 gene. Further functional studies of variants of this specific gene are needed to illustrate the pathogenic mechanism(s) that underlie hearing impairment.

miR-222 attenuates cisplatin-induced cell death by targeting the PPP2R2A/Akt/mTOR Axis in bladder cancer cells.

Increased miR-222 levels are associated with a poor prognosis in patients with bladder cancer. However, the role of miR-222 remains unclear. In the present study, we found that miR-222 enhanced the proliferation of both the T24 and the 5637 bladder cancer cell lines. Overexpression of miR-222 attenuated cisplatin-induced cell death in bladder cancer cells. miR-222 activated the Akt/mTOR pathway and inhibited cisplatin-induced autophagy in bladder cancer cells by directly targeting protein phosphatase 2A subunit B (PPP2R2A). Blocking the activation of Akt with LY294002 or mTOR with rapamycin significantly prevented miR-222-induced proliferation and restored the sensitivity of bladder cancer cells to cisplatin. These findings demonstrate that miR-222 modulates the PPP2R2A/Akt/mTOR axis and thus plays a critical role in regulating proliferation and chemotherapeutic drug resistance. Therefore, miR-222 may be a novel therapeutic target for bladder cancer.

Identification of PRRT2 as the causative gene of paroxysmal kinesigenic dyskinesias.

Paroxysmal kinesigenic dyskinesias is a paroxysmal movement disorder characterized by recurrent, brief attacks of abnormal involuntary movements induced by sudden voluntary movements. Although several loci, including the pericentromeric region of chromosome 16, have been linked to paroxysmal kinesigenic dyskinesias, the causative gene has not yet been identified. Here, we identified proline-rich transmembrane protein 2 (PRRT2) as a causative gene of paroxysmal kinesigenic dyskinesias by using a combination of exome sequencing and linkage analysis. Genetic linkage mapping with 11 markers that encompassed the pericentromeric of chromosome 16 was performed in 27 members of two families with autosomal dominant paroxysmal kinesigenic dyskinesias. Then, the whole-exome sequencing was performed in three patients from these two families. By combining the defined linkage region (16p12.1-q12.1) and the results of exome sequencing, we identified an insertion mutation c.649_650InsC (p.P217fsX7) in one family and a nonsense mutation c.487C>T (p.Q163X) in another family. To confirm our findings, we sequenced the exons and flanking introns of PRRT2 in another three families with paroxysmal kinesigenic dyskinesias. The c.649_650InsC (p.P217fsX7) mutation was identified in two of these families, whereas a missense mutation, c.796C>T (R266W), was identified in another family with paroxysmal kinesigenic dyskinesias. All of these mutations completely co-segregated with the phenotype in each family. None of these mutations was identified in 500 normal unaffected individuals of matched geographical ancestry. Thus, we have identified PRRT2 as the first causative gene of paroxysmal kinesigenic dyskinesias, warranting further investigations to understand the pathogenesis of this disorder.

[Analysis of CX32 gene mutation and related clinical features in Chinese Han Charcot-Marie-Tooth families].

OBJECTIVE: To analyze the mutation of CX32 gene and related clinical features in Chinese Han patients with Charcot-Marie-Tooth (CMT) disease. METHODS: Thirty-four CMT families, from 2004 to 2011 at Departments of Neurology, Xiangya Hospital, Third Xiangya Hospital and National Key Laboratory of Medical Genetics, were selected for CX32 mutation screening after the exclusion of the PMP22 duplication and male-to-male transmission. Mutation analysis was carried out by polymerase chain reaction (PCR) plus direct sequencing. Analyses of clinical, electrophysiological and pathological features in 11 patients from 6 CMTX1 families were performed by 2 neurologists. RESULTS: Five CX32 gene mutations were detected in 6 CMT families: c.37G > A, c.65G > A, c.246C > G, c.256A > G and c.533A > G. Among them, c.246C > G and c.533A > G were firstly reported. The clinical manifestations included progressive distal muscle atrophy and weakness, areflexia, sensory abnormalities and pes vacus. Nerve conduction velocity ranged from 21.7 to 49.3 m/s. Both demyelination and axonal degeneration were detected in nerve biopsy. CONCLUSIONS: CMT1X has a frequency of around 9% in our study. The male patients tend to have more serious clinical features and their electrophysiological and pathological changes are intermediate. CX32 mutation analysis helps to confirm the genetic diagnosis of CMT so as to provide genetic counseling and reproductive guidance and elucidate its pathogenesis.

Loss of the collagen IV modifier prolyl 3-hydroxylase 2 causes thin basement membrane nephropathy.

The glomerular filtration barrier (GFB) produces primary urine and is composed of a fenestrated endothelium, a glomerular basement membrane (GBM), podocytes, and a slit diaphragm. Impairment of the GFB leads to albuminuria and microhematuria. The GBM is generated via secreted proteins from both endothelial cells and podocytes and is supposed to majorly contribute to filtration selectivity. While genetic mutations or variations of GBM components have been recently proposed to be a common cause of glomerular diseases, pathways modifying and stabilizing the GBM remain incompletely understood. Here, we identified prolyl 3-hydroxylase 2 (P3H2) as a regulator of the GBM in an a cohort of patients with albuminuria. P3H2 hydroxylates the 3' of prolines in collagen IV subchains in the endoplasmic reticulum. Characterization of a P3h2ΔPod mouse line revealed that the absence of P3H2 protein in podocytes induced a thin basement membrane nephropathy (TBMN) phenotype with a thinner GBM than that in WT mice and the development of microhematuria and microalbuminuria over time. Mechanistically, differential quantitative proteomics of the GBM identified a significant decrease in the abundance of collagen IV subchains and their interaction partners in P3h2ΔPod mice. To our knowledge, P3H2 protein is the first identified GBM modifier, and loss or mutation of P3H2 causes TBMN and focal segmental glomerulosclerosis in mice and humans.

TGM6 identified as a novel causative gene of spinocerebellar ataxias using exome sequencing.

Autosomal-dominant spinocerebellar ataxias constitute a large, heterogeneous group of progressive neurodegenerative diseases with multiple types. To date, classical genetic studies have revealed 31 distinct genetic forms of spinocerebellar ataxias and identified 19 causative genes. Traditional positional cloning strategies, however, have limitations for finding causative genes of rare Mendelian disorders. Here, we used a combined strategy of exome sequencing and linkage analysis to identify a novel spinocerebellar ataxia causative gene, TGM6. We sequenced the whole exome of four patients in a Chinese four-generation spinocerebellar ataxia family and identified a missense mutation, c.1550T-G transition (L517W), in exon 10 of TGM6. This change is at a highly conserved position, is predicted to have a functional impact, and completely cosegregated with the phenotype. The exome results were validated using linkage analysis. The mutation we identified using exome sequencing was located in the same region (20p13-12.2) as that identified by linkage analysis, which cross-validated TGM6 as the causative spinocerebellar ataxia gene in this family. We also showed that the causative gene could be mapped by a combined method of linkage analysis and sequencing of one sample from the family. We further confirmed our finding by identifying another missense mutation c.980A-G transition (D327G) in exon seven of TGM6 in an additional spinocerebellar ataxia family, which also cosegregated with the phenotype. Both mutations were absent in 500 normal unaffected individuals of matched geographical ancestry. The finding of TGM6 as a novel causative gene of spinocerebellar ataxia illustrates whole-exome sequencing of affected individuals from one family as an effective and cost efficient method for mapping genes of rare Mendelian disorders and the use of linkage analysis and exome sequencing for further improving efficiency.

[Linkage analysis of susceptibility loci in 2 target chromosomes in pedigrees with paranoid schizophrenia and undifferentiated schizophrenia].

OBJECTIVE: To investigate the relationship of susceptibility loci in chromosomes 1q21-25 and 6p21-25 and schizophrenia subtypes in Chinese population. METHODS: A genomic scan and parametric and non-parametric analyses were performed on 242 individuals from 36 schizophrenia pedigrees, including 19 paranoid schizophrenia and 17 undifferentiated schizophrenia pedigrees, from Henan province of China using 5 microsatellite markers in the chromosome region 1q21-25 and 8 microsatellite markers in the chromosome region 6p21-25, which were the candidates of previous studies. All affected subjects were diagnosed and typed according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revised (DSM-IV-TR; American Psychiatric Association, 2000). All subjects signed informed consent. RESULTS: In chromosome 1, parametric analysis under the dominant inheritance mode of all 36 pedigrees showed that the maximum multi-point heterogeneity Log of odds score method (HLOD) score was 1.33 (α = 0.38). The non-parametric analysis and the single point and multi-point nonparametric linkage (NPL) scores suggested linkage at D1S484, D1S2878, and D1S196. In the 19 paranoid schizophrenias pedigrees, linkage was not observed for any of the 5 markers. In the 17 undifferentiated schizophrenia pedigrees, the multi-point NPL score was 1.60 (P= 0.0367) at D1S484. The single point NPL score was 1.95(P= 0.0145) and the multi-point NPL score was 2.39 (P= 0.0041) at D1S2878. Additionally, the multi-point NPL score was 1.74 (P= 0.0255) at D1S196. These same three loci showed suggestive linkage during the integrative analysis of all 36 pedigrees. In chromosome 6, parametric linkage analysis under the dominant and recessive inheritance and the non-parametric linkage analysis of all 36 pedigrees and the 17 undifferentiated schizophrenia pedigrees, linkage was not observed for any of the 8 markers. In the 19 paranoid schizophrenias pedigrees, parametric analysis showed that under recessive inheritance mode the maximum single-point HLOD score was 1.26 (α = 0.40) and the multi-point HLOD was 1.12 (α = 0.38) at D6S289 in the chromosome 6p23. In nonparametric analysis, the single-point NPL score was 1.52 (P= 0.0402) and the multi-point NPL score was 1.92 (P= 0.0206) at D6S289. CONCLUSION: Susceptibility genes correlated with undifferentiated schizophrenia pedigrees from D1S484, D1S2878, D1S196 loci, and those correlated with paranoid schizophrenia pedigrees from D6S289 locus are likely present in chromosome regions 1q23.3 and 1q24.2, and chromosome region 6p23, respectively.

[Mutation analysis of LITAF, RAB7, LMNA and MTMR2 genes in Chinese Charcot-Marie-Tooth disease.].

The purpose of this study was to understand the mutation features of lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF), ras-associated protein RAB7 (RAB7), lamin A/C (LMNA) and myotubularin-related protein 2 (MTMR2) genes in Chinese Charcot-Marie-Tooth disease (CMT) patients. Mutation analysis of LITAF gene was carried out using PCR combined with DNA sequencing, and mutation analysis of RAB7 gene by PCR-single strand conformation polymorphism (PCR-SSCP) combined with DNA sequencing in 33 CMT patients including 6 probands of autosomal domi-nated CMT families and 27 sporadic patients; mutation analysis of LMNA and MTMR2 genes was observed using PCR-SSCP combined with DNA sequencing in 41 CMT patients, including 14 probands of autosomal recessive CMT fami-lies and 27 sporadic patients. Two sequence variations c.269G-->A and c.274A-->G were detected in LITAF gene and two sequence variations c.1243G-->A and c.1910C-->T were detected in LMNA gene. No sequence variation was found in RAB7 and MTMR2 gene. Variations of c.269G-->A in LITAF gene and c.1243G-->A, c.1910C-->T in LMNA gene are newly found SNPs in this study. Variation of c.274A-->G in LITAF gene is known SNP reported in SNP database. Mutations in LITAF, RAB7, LMNA, and MTMR2 genes are rare in Chinese CMT patients.

Mutation analysis of CAPN1 in Chinese populations with spastic paraplegia and related neurodegenerative diseases.

BACKGROUND: Mutations in CAPN1 have recently been reported to cause the spastic paraplegia 76 (SPG76) subtype of hereditary spastic paraplegia (HSP). To investigate the role of CAPN1 in spastic paraplegia and other neurodegenerative diseases, including spinocerebellar ataxia (SCA), early-onset Parkinson's disease (EOPD), and amyotrophic lateral sclerosis (ALS) we conducted a mutation analysis of CAPN1 in a cohort of Chinese patients with SPG, SCA, EOPD, and ALS. METHODS: Variants of CAPN1 were detected in the three cohorts by Sanger or whole-exome sequencing, and all exons and exon-intron boundaries of CAPN1 were analysed. RESULTS: A novel CAPN1 splicing variant (NM_001198868: c.338-1G > A) identified in a familial SPG/SCA showed a complex phenotype, including spastic paraplegia, ataxia, and extensor plantar response. This mutation was confirmed by Sanger sequencing and completely co-segregated with the phenotypes. Sequencing of the cDNA from the three affected patients detected a guanine deletion (c.340_340delG) that was predicted to result in an early stop codon after 61 amino acids (p. D114Tfs*62). No CAPN1 pathogenic mutation was found in the EOPD or ALS groups. CONCLUSION: Our data reveal a novel CAPN1 mutation found in patients with SPG/SCA and emphasize the spastic and ataxic phenotypes of SPG76, but CAPN1 may not play a major role in EOPD and ALS.

[Mutation analysis of MFN2 gene in Chinese patients with Charcot-Marie-Tooth disease].

OBJECTIVE: To analyze MFN2 gene mutation in Chinese patients Charcot-Marie-Tooth disease (CMT) and to establish a quick and effective diagnostic method. METHODS: Through denaturing high-performance liquid chromatography (DHPLC) combined with DNA sequencing, MFN2 gene mutation analysis was carried out in 35 Chinese CMT2 patients including 9 probands of CMT2 pedigree and 26 sporadic CMT2 patients. RESULTS: The investigators found three abnormal sequence variations in MFN2 gene: c.281G-->A, c.395G-->A and c.408A-->T. c.395G-->A (C132T) was a novel causative missense mutation firstly reported while c.281G-->A (R94Q) a hotspot mutation and c.408A-->T (V136V) a single nucleotide polymorphism (SNP). The accuracy and specificity of DHPLC detection reached up to 100%. CONCLUSION: Through DHPLC combined with DNA sequencing, MFN2 mutations are detected in Chinese CMT2 patients. There are two causative missense mutations: c.395G-->A (C132T) and c.281G-->A (R94Q) and one SNP c.408A-->T (V136V). Such a method is an effective and economic diagnostic screening tool of MFN2 gene in CMT patients on a large scale.

[Mutations of Cx26 gene in patients with NSHL and intracellular distribution of two mutants].

To analyze the frequencies and characteristics of Cx26 gene mutations in Chinese patients with nonsyndromic hearing loss (NSHL) and investigate the intracellular localization of two mutants, 139 unrelated familial cases with non-syndromic hearing loss were screened for mutation in Cx26 gene by direct sequencing. Two mutants, p.F115C and p.V37I, were structured into pEGFP vectors and transfected into Hela cells to detect their expression and fluorescent localization in cells. Cx26 variations were detected in 31 patients, with a detection rate of 22.3%. The 10 variations included 6 types of mutations and 4 types of polymorphisms. A novel variation p.F115C was found. The fluorescent localization assay of the two mutants p.F115C and p.V37I showed no difference from the wild-type, indicating that both mutants did not impair the formation of the gap junctions.

[Mutation screening of 20 candidate genes located in chromo-some 5q31-5q32 for DFNA52 locus].

Previously, we mapped the DFNA52 (OMIM: 607683) locus to an 8.8 cM interval between STR D5S2056 and D5S638 on human chromosome 5q31.1-q32 in a large consanguineous Chinese family with congenital sensorineural hearing loss. Positional candidate cloning approach was applied to analyze the candidate genes in this region. We analyzed 20 genes according to cochlear expression pattern, which were also located in the DFNA52 interval as candidate genes. Sequencing of the coding and splice site regions of these genes did not reveal any potentially pathogenic mutations segregating with the disease, implying that none of these genes are likely virulence gene for DFNA52.

[A novel mutation of CYP1B1 gene in primary congenital glaucoma].

OBJECTIVE: To investigate the distribution of the CYP1B1 (Cytochrome P450, family 1, subfamily B, polypeptide 1) gene mutations in primary congenital glaucoma (PCG) in Hunan Province. METHODS: Case-control study. Thirteen cases of PCG from different districts of Hunan province were collected in this study. Direct sequencing was used to evaluate the coding and the promoter regions of the CYP1B1 gene in PCG patients. RESULTS: A novel pathogenic mutation (c.C319G, L107V) was identified in a PCG patient in our study and it was a missense mutation in exon 2. Additionally, four single nucleotide polymorphisms(SNPs) were found in PCG patients, including R48G, A119S, V432L and D449D. CONCLUSION: A novel CYP1B1 gene mutation (L107V) may be the cause for primary congenital glaucoma in Hunan Province.