OBJECTIVE To map and detect the gene responsible for congenital nuclear cataract in a Chinese family. METHODS Genomic DNA was extracted from the peripheral blood samples of members of the pedigree. Gene scan was performed using approximately 400 microsatellite markers spaced at about 10 cM intervals (ABI). Linkage analysis was carried out using a Linkage software package. Additional microsatellite markers for the positive region were selected for precise targeting, and haplotype data were processed using Cyrillic software to define the region of the disease gene. Mutation detection was carried out by sequencing candidate genes. RESULTS Suggestive evidence of linkage was detected at marker D2S325 (LOD score [Z] = 2.29, recombination fraction [theta] = 0.00). Precise targeting and haplotype analysis traced the disease gene to a 19.04 cM region bounded by D2S117 and D2S2382 on chromosome 2q32.3-q35. Direct sequencing of the candidate gene cluster revealed a G-->A transversion in exon 3 of CRYGC. CONCLUSIONS The present study has identified a novel nonsense mutation in CRYGC associated with congenital nuclear cataracts in a Chinese family.