Genotypic Analysis of ABCA4 Coding Sequence in Thai Patients with Stargardt Disease

Objective: To study the mutational spectrum of the ABCA4 gene in Thai patients with Stargardt disease. Materials and Methods: DNA sequencing of all 50 exons of the ABCA4 gene was performed in nine Thai patients with clinically diagnosed Stargardt disease. Results: Amino acid sequence variation in the ABCA4 gene was found in five patients. Six missense mutations, c.71G>A, c.635G>A, c.1268A>G, c.3626T>C, c.4283C>T, and c.5761G>A, previously associated with Stargardt disease, were identified in our cohort. The variant c.1268A>G was the most prevalent in our study. Conclusion: In this cohort, only 56% of Thai Stargardt patients had missense mutations in the ABCA4 gene. Mutations in the non-coding regions of the ABCA4 or mutations in other genes may be responsible for Stargardt phenotypes in the remaining patients. Our findings are the first to reveal the mutational spectrum of ABCA4 leading to Stargardt disease in the Thai population and demonstrate a potential for ABCA4 screening as well as the importance of genetic variability in Thai patients with clinically suspected Stargardt disease.