Abstract
Purpose: :
To identify the potential pathogenic mutation over five generations of a Chinese family with congenital COPPOCK cataracts.
Methods: :
We investigated five generations of a Chinese family who are afflicted with COPPOCK cataracts. The family resides in a relatively isolated region of Northern China. There are 150 members in this large family. All participants provided informed consent in accordance with the Declaration of Helsinki. Peripheral blood samples were collected from all of the family members, and genomic DNA was then extracted from the blood samples. A gene scan was performed using about 400 primers labeled with fluorescent stain. Linkage software defined the region of the diseased gene with a Linkage analysis, and Cyrillic software processed the resulting haplotypes. Mutation detection was carried out in the candidate gene by sequencing amplified products.
Results: :
Maximum LOD score was obtained at marker D13S175(LOD score [Z] =6.82, recombination fraction [θ] =0.0. Haplotype analysis traced the disease gene to a 6.99 cM region bounded by D13S1316 and D13S1275 on chromosome13q12.11. Direct sequencing of the candidate GJA3 gene revealed a c.427G>A transition in exon 2 of GJA3 that co-segregated with the cataract in the family members and was not observed in 100 control patients. This single-nucleotide change resulted in the substitution of a highly conserved Glycine by Arginine (G143R).
Conclusions: :
The present study identified a missense mutation (G143R) in the GJA3 gene that causes autosomal dominant congenital COPPOCK cataracts in a large Chinese family.
Keywords: genetics • gene mapping • gene screening