title: A novel Cx50 (GJA8) p.H277Y mutation associated with autosomal dominant congenital cataract identified with targeted next-generation sequencing.
abstract: BACKGROUND
  To unravel the molecular genetic background responsible for autosomal dominant congenital pulverulent nuclear cataracts in a four-generation Chinese family.
  
  
  METHODS
  Family history data were collected, ophthalmological examinations were performed, and genomic DNA was extracted from peripheral blood of the family members. The candidate genes were captured and sequenced by targeted next-generation sequencing, and the results were confirmed by Sanger sequencing. The structure modelling of the protein was displayed based on Swiss-Model Server, and its possible changes in the secondary structure were predicted using Antheprot 2000 software. The chemical dissimilarity and possible functional impact of an amino acid substitution were performed with Grantham score, PolyPhen-2, and SIFT predictions. Protein distributions were assessed by confocal microscopy.
  
  
  RESULTS
  A novel heterozygous c.829C > T transition that led to the substitution of a highly conserved histidine by tyrosine at codon 277 (p.H277Y) in the coding region of connexin50 (Cx50, GJA8) was identified. Bioinformatics analysis showed that the mutation likely altered the secondary structure of the protein by replacing the helix of the COOH-terminal portion with a turn. The mutation was predicted to be moderately conservative by Grantham score and to be deleterious by both PolyPhen-2 and SIFT with consistent results. In addition, when expressed in COS1 cells, the mutation led to protein accumulation and caused changes in Cx 50 protein localization pattern.
  
  
  CONCLUSIONS
  This is a novel missense mutation [c.829C > T, (p.H277Y)] identified in exon 2 of Cx50. Our findings expand the spectrum of Cx50 mutations that are associated with autosomal dominant congenital pulverulent nuclear cataract.
authors.affiliation: Department of Ophthalmology, Shanghai First People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Chong
authors.initials: C
authors.lastname: Chen
authors.forename: Qiao
authors.initials: Q
authors.lastname: Sun
authors.forename: Mingmin
authors.initials: M
authors.lastname: Gu
authors.forename: Kun
authors.initials: K
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Sun
authors.forename: Xun
authors.initials: X
authors.lastname: Xu
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D044466:Asian People / Q000235:genetics; D001483:Base Sequence; D015153:Blotting, Western; D002386:Cataract / Q000235:genetics*; D002648:Child; D002681:China / Q000453:epidemiology; D017630:Connexins / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010375:Pedigree; D017433:Protein Structure, Secondary; D014162:Transfection; D055815:Young Adult; D000099264:Connexin 50
chemical_list: D017630:Connexins; D000099264:Connexin 50