Genetic investigation of ocular developmental genes in 52 patients with anophthalmia/microphthalmia

Mutation in eye developmental genes has been reported to cause anophthalmia and microphthalmia. However, in India, especially in the Western Indian population, such reports are scarce. Hence, the present study aims to investigate mutations in 15 ocular developmental genes in patients with anophthalmia and microphthalmia in the western region of India.

Genomic DNA was isolated from the blood of 52 individuals affected with microphthalmia and anophthalmia, and 50 healthy normal controls. Polymerase chain reaction (PCR) was carried out for 15 genes including BMP4, CRYBA4, FOXE3, GDF6, GJA3, GJA8, MITF, OTX2, PAX6, PITX3, RAX, SIX3, SIX6, SOX2, and VSX2 using gene-specific primers spanning the exon-intron boundaries and part of a promoter region. The amplified PCR products were purified and then subjected to Sanger's bi-directional sequencing. Nucleotide variations were examined using a basic local alignment search tool (BLAST).

Bi-directional sequencing identified 8 novel and 14 known variations. Out of this, the variations GJA3-c.92T>A; p.Ile31Asn, SOX2-c.542C>A; p.Pro181Gln and SOX2-c.541_542delinsGA; p.Pro181Glu were found to be deleterious by in silico analysis. The GJA3-p.Ile31Asn mutation was identified in a patient with bilateral microphthalmia, microcornea, and membranous cataract. The SOX2-p.Pro181Gln and SOX2-p.Pro181Glu mutations were identified in patients with isolated bilateral microphthalmia and microphthalmia with microcornea, respectively. A novel nondeleterious missense variation was identified in the GJA8 gene in a patient with anophthalmia.

These results support the crucial role of GJA3 and SOX2 in eye development and indicate a detailed functional study to understand the molecular mechanisms underlying the disease pathology.