论文部分内容阅读
PURPOSE. To study some functional candidate genes in cataract families of Indi an descent. METHODS. Nine Indian families, clinically documented to have congeni tal/childhood cataracts, were screened for mutations in candidate genes such as CRYG (A→D), CRYBB2, and GJA8 by PCR analyses and sequencing. Genomic DNA sample s of either probands or any representative affected member of each family were P CR amplified and sequenced commercially. Documentation of single nucleotide poly morphisms (SNPs) and candidate mutations was done through BLAST SEARCH(http://ww w.ncbi.nlm.nih.gov/ blast/Blast.- cgi?). RESULTS. Several single nucleotide polymorphisms in CRYG, CRYBB2, and G JA8 genes were observed. Because they do not co-segregate with the phenotype, t hey were excluded as candidates for the cataract formation in these patients. However, a substitution (W151C in exon 6 of CRYBB2) was identi fied as the most likely causative mutation underlying the phenotype of central n uclear cataract in all affected members of family C176. Protein structural inter pretations demonstrated that no major structural alterations could be predicted and that even the hydrogen bonds to the neighboring Leu166 were unchanged. Surpr isingly, hydropathy analysis of the mutant βB2-crystallin featuring the amino acids at position 147 to 155, further increased the hydrophobicity, which might impair the solubility of the mutant protein. Finally, the Cys residue at positio n 151 might possibly be involved in intramolecular disulphide bridges with other cysteines during translation, possibly leading to dramatic structural changes. CONCLUSIONS. Exon 6 of CRYBB2 appears to be a critical region susceptible for mu tations leading to lens opacity.
METHODS. Nine Indian families, clinically documented to have congeni tal / childhood cataracts, were screened for mutations in candidate genes such as CRYG (A → D), CRYBB2, and GJA8 by PCR analyzes and sequencing. Genomic DNA sample s of either probands or any representative affected member of each family were P CR amplified and sequenced commercially. Documentation of single nucleotide poly morphisms (SNPs) and candidate mutations was done through BLAST SEARCH (http RESULTS: Several single nucleotide polymorphisms in CRYG, CRYBB2, and G JA8 genes were observed. Because they do not co-segregate with the phenotype, t hey were excluded as candidates for the cataract formation in these patients. However, a substitution (W151C in exon 6 of CRYBB2) was identi fied as the most likely causative mutation underlying the phenotype of central n uclear cataract in a ll affected members of family C176. Protein structural inter pretations said that no major structural alterations could be predicted and that even the hydrogen bonds to the neighboring Leu166 were unchanged. Surpr isingly, hydropathy analysis of the mutant βB2-crystallin featuring the amino acids at position 147 to 155, further increased the hydrophobicity, which might impair the solubility of the mutant protein. Finally, the Cys residue at positio n 151 might possibly be involved in intramural disulphide bridges with other cysteines during translation, possibly leading to dramatic structural changes. CONCLUSIONS Exon 6 of CRYBB2 appears to be a critical region susceptible for mu tations leading to lens opacity.