Mutation screening and genotype phenotype correlation of α-crystallin, γ-crystallin, and GJA8 gene in congenital cataract

摘要

Purpose: To screen α-crystallin (CRYAB),γ-crystallin (CRYGC and CRYGD), and Connexin 50 (Cx-50or GJA8) genes in congenital cataract patients and controls. Methods: Thirty clinically diagnosedcongenital cataract cases below 3 years of age from northern India,presenting at Dr. R. P. Centre for Ophthalmic Sciences (AIIMS, NewDelhi, India) were enrolled in this study. Genomic DNA was extractedfrom peripheral blood, all coding and exon/intron regions wereamplified using PCR and direct sequencing was performed to detect anynucleotide variation. ProtScale and Discovery Studio programs were usedfor insilico and structural analysis of non-synonymous mutations. Results: DNA sequencing analysis of CRYAB,CRYGC, CRYGD, and GJA8 showed a total of six variations ofwhich two were novel (CRYGC:p.R48H and GJA8:p.L281C) andfour have been previously reported (CRYAB: rs11603779TG, 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 andc.T564C) were found in 90% of the patients. Insilico and structuralanalysis data suggested that two novel non-synonymous mutations alteredthe stability and solvent accessibility of γC-crystallin and Cx-50proteins which may lead to lens opacification. Conclusions: We observed two novelnonsynonymous variations and four reported variations in CRYAB,CRYGC, CRYGD, and GJA8. The p.R48H variation inγC-crystallin may disrupt the normal structure of lens and can causecataract. Cx50 is responsible for joining the lens cells into afunctional syncytium and a mutation (p.L281C) in GJA8 may leadto lens opacification resulting in cataract formation. This studyfurther expands the mutation spectrum of congenital cataract and helpunderstanding how mutant proteins lead to opacification of lens.