CRYGD) and two genes coding for gap junctional channel protein (GJA3, GJA8), one gene coding for heat-shock tran-

Congenital cataracts are a significant cause of visual impairment in childhood. They have a high incidence and are a significant cause of vision loss world wide causing approximately one tenth of childhood blindness [1]. Roughly 50% of congenital cataracts are hereditary and family studies have revealed that approximately 30% of children with bilateral isolated congenital cataract had a genetic basis [2]. Congenital cataract is phenotypically and genetically heterogeneous. To date, congenital cataracts, isolated or syndromic forms, have been mapped to 27 genetic loci, and the disease-associated mutations have been identified in 18 genes, including those coding for αA-crystallin [3,4], αB-crystallin [5], βA1-crystallin [6,7], βB1-crystallin [8], βB2-crystallin [9], γC-crystallin [10], γD-crystallin [11-13], beaded filament structural protein 2 [14], heat shock transcription factor 4 [15], gap junction protein alpha-3 [16], gap junction protein alpha-8 [17], paired-like homeodomain transcription factor-3 [18,19], ferritin [20], galactokinase 1 [21], glucosaminyl(Nacetyl)transferase 2 [22], major intrinsic protein of lens fiber (MIP) [23], lens intrinsic membrane protein 2 (LIM2) [24], and paired box gene 6 [25]. Among them, 12 distinct genes have been identified to cause nonsyndromic autosomal dominant cataracts, including seven genes coding for crystallin (CRYAA, CRYAB, CRYBA1/A3, CRYBB1, CRYBB2, CRYGC, CRYGD) and two genes coding for gap junctional channel protein (GJA3, GJA8), one gene coding for heat-shock transcription factor 4 gene (HSF4), one gene coding for major intrinsic protein (MIP), and one gene coding for beaded filament structural protein 2 (BFSP2). Also, a mutation in CRYGS with autosomal dominant cataract in humans was recently reported [26]. In our study, we performed linkage analysis on a four generation Chinese family with nuclear golden crystal cataracts by using STRs markers on 12 ADCC loci and haplotype analysis with makers on 2q33-q35. A missense mutation in exon 2 of the CRYGD gene was identified, which is responsible for the disease in this pedigree.