OBJECTIVETo identify the mutations in the gap junction protein alpha3/alpha8 gene (GJA3 or GJA8) in the Chinese family with autosomal dominant congenital cataract (ADCC).

METHODSAll subjects(5 family members and 100 unrelated control individuals)were undergone comprehensive ophthalmic examination, and genomic DNA was extracted from peripheral blood (5 mL). The exons and flanking introns of GJA3/GJA8 genes were amplified by polymerase chain reaction (PCR). Purified PCR products were then sequenced directly for screening disease-causing mutations.

RESULTSUpon bidirectional sequence analysis, a G-->A transition at nucleotide 138 (c.138G>A)in exon 2 of GJA8 was found, resulting in synonymous mutation of glycine (GGG) to glycine (GGA). An additional G-->T transvertion at nucleotide 139 (c.139G>T) in exon 2 of GJA8, resulting in a missense mutation of asparagines (GAU) to tyrosine (UAU) at codon 47 (D47Y). These two alterations were not seen in all unaffected members and 100 unrelated control individuals. Bioinformatic analyses also showed that a highly conserved region was located at Asp47. Meanwhile no sequence variations for GJA3 were detected from the 3 affected members.

CONCLUSIONA novel disease-causing mutation (D47Y) of GJA8 gene in a Chinese family with ADCC is reported.