Sequencing of the coding regions of the CRYGA, B, C, and D genes showed the presence of a heterozygous C>A transversion in exon 2 of CRYGD that is associated with cataracts in this family.
Mutation screening was performed in the cataract candidate genes coding for crystallins and connexin 50 by sequencing of polymerase chain reaction (PCR) products amplified from blood leukocyte DNA samples of eight family members.
The mutation observed in CRYAA in the present family highlights the phenotypic heterogeneity of the disorder in relation to the genotype, as an identical mutation has previously been reported in an American family with a different type of cataract.
The cataract locus in this family constellation was mapped to 1q21.1 and 21.44 cM interval between D1S2344 and D1S2844, which were known to flank the gene coding Connexin 50 (Cx50) or gap junction protein alpha-8 (GJA8).
A novel nonsense mutation in CRYGC was detected in a Chinese family with consistent autosomal dominant congenital nuclear cataract, providing clear evidence of a relationship between the genotype and the corresponding cataract phenotype.
A c.752T-->C mutation in exon 6 of CRYBB1 gene, which resulted in a heterozygous S228P mutation in predicted protein, was found to cosegregate with cataract in the family.
A missense mutation, Gly154Glu, was found in LIM2 in one family with four individuals diagnosed with autosomal recessive cataract from two generations.
The HSF4 mutations have been reported in four families with autosomal dominant cataracts and, recently, in a single kindred with autosomal recessive congenital cataract.