Objective: To identify genetic defects associated with autosomal dominant congenital golden crystal nuclear cataract (ADCC) in a Chinese pedigree of northern China.
Methods: Clinical data were collected and the lens changes of the affected members in this family were recorded by slit lamp photography. Genomic DNA was obtained from blood leucocytes. Linkage analyses was conducted using polymorphisms of 21 microsatellite markers and mutational analyses of candidate genes was studied by direct sequencing.
Results: The maximum LOD score (1.505 at recombination fraction theta = 0.00) was obtained at markers D2S1782, D2S1384 and D2S1385 near the gamma-crystallin gene (CRYG) cluster within 2q33 - q35. Sequencing analysis of the coding regions of the CRYGA. B, C, and D genes showed that the there was a heterozygous C-->A transversion at position 109 (R36S) in exon 2 of CRYGD gene, which was co-segregated with the affected members.
Conclusions: R36S mutation in CRYGD gene results in an ADCC phenotype that is different from previous reports. This finding indicates that the presence of phenotypic heterogeneity of cataract, especially in different races. This is the first report of congenital cataract caused by R36S mutation in CRYGD gene.