title: Mutation screening and genotype phenotype correlation of α-crystallin, γ-crystallin and GJA8 gene in congenital cataract.
abstract: OBJECTIVE
  To screen α-crystallin (CRYAB), γ-crystallin (CRYGC and CRYGD), and Connexin 50 (Cx-50 or GJA8) genes in congenital cataract patients and controls.
  
  
  METHODS
  Thirty clinically diagnosed congenital cataract cases below 3 years of age from northern India, presenting at Dr. R. P. Centre for Ophthalmic Sciences (AIIMS, New Delhi, India) were enrolled in this study. Genomic DNA was extracted from peripheral blood, all coding and exon/intron regions were amplified using PCR and direct sequencing was performed to detect any nucleotide variation. ProtScale and Discovery Studio programs were used for insilico and structural analysis of non-synonymous mutations.
  
  
  RESULTS
  DNA sequencing analysis of CRYAB, CRYGC, CRYGD, and GJA8 showed a total of six variations of which two were novel (CRYGC:p.R48H and GJA8:p.L281C) and four have been previously reported (CRYAB: rs11603779T>G, GJA8: p.L268L, CRYGD: p.R95R, and c.T564C). Both the novel changes, in CRYGC and GJA8 were found in 16.6% of the patients. Previously reported nucleotide alterations (CRYGD:p.R95R and c.T564C) were found in 90% of the patients. Insilico and structural analysis data suggested that two novel non-synonymous mutations altered the stability and solvent accessibility of γC-crystallin and Cx-50 proteins which may lead to lens opacification.
  
  
  CONCLUSIONS
  We observed two novel nonsynonymous variations and four reported variations in CRYAB, CRYGC, CRYGD, and GJA8. The p.R48H variation in γC-crystallin may disrupt the normal structure of lens and can cause cataract. Cx50 is responsible for joining the lens cells into a functional syncytium and a mutation (p.L281C) in GJA8 may lead to lens opacification resulting in cataract formation. This study further expands the mutation spectrum of congenital cataract and help understanding how mutant proteins lead to opacification of lens.
authors.affiliation: Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Manoj
authors.initials: M
authors.lastname: Kumar
authors.forename: Tushar
authors.initials: T
authors.lastname: Agarwal
authors.forename: Sudarshan
authors.initials: S
authors.lastname: Khokhar
authors.forename: Manoj
authors.initials: M
authors.lastname: Kumar
authors.forename: Punit
authors.initials: P
authors.lastname: Kaur
authors.forename: Tara Sankar
authors.initials: TS
authors.lastname: Roy
authors.forename: Rima
authors.initials: R
authors.lastname: Dada
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002386:Cataract / Q000151:congenital* / Q000235:genetics* / Q000473:pathology; D002675:Child, Preschool; D019295:Computational Biology; D017630:Connexins / Q000737:chemistry / Q000235:genetics*; D004252:DNA Mutational Analysis; D005136:Eye Proteins / Q000737:chemistry / Q000235:genetics*; D056726:Genetic Association Studies; D005820:Genetic Testing; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007223:Infant; D007231:Infant, Newborn; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011487:Protein Conformation; D016415:Sequence Alignment; D038203:alpha-Crystallin B Chain / Q000235:genetics; D038201:alpha-Crystallins / Q000737:chemistry / Q000235:genetics*; D038222:gamma-Crystallins / Q000737:chemistry / Q000235:genetics*; D000099264:Connexin 50
chemical_list: D017630:Connexins; D005136:Eye Proteins; D038203:alpha-Crystallin B Chain; D038201:alpha-Crystallins; D038222:gamma-Crystallins; D000099264:Connexin 50; C059215:CRYAB protein, human; C504903:CRYGD protein, human; C522806:Crygc protein, human