Lack of Association of IVS8+4 C/T and IVS8+32 T/C Polymorphisms in the OPA1 Gene With Normal Tension Glaucoma in Patients From Singapore, India and Japan

Abstract

Abstract: : Purpose:The IVS8+4 C/T;+32T/C polymorphisms in the OPA1 gene were found to be associated with normal tension glaucoma (NTG) in British Caucasian subjects. We have investigated the association of these polymorphisms in NTG subjects from Singapore, India and Japan. Methods: The inclusion criteria for NTG was the presence of glaucomatous optic neuropathy (defined as loss of neuro retinal rim with a cup:disc ratio of 0.6 or greater) with compatible visual field loss and open angles on gonioscopy, and a mean IOP without treatment that was consistently < 21 mm Hg on diurnal testing. The exon 8 of the OPA1 gene was PCR amplified and then subjected to bi–directional sequencing using BigDye Terminator v3.1 chemistries and analyzed on an ABI PRISM 3100/310 Genetic Analyser. Results: A cohort of 53 Singaporean Chinese, 50 Asian Indians and 42 Japanese were included in the study. There was not any significant difference in the distribution of these two polymorphisms in the 3 ethnic groups. The data when compared with unrelated healthy controls did not reveal any significant difference. There were racial differences in the prevalence of these OPA1 polymorphisms. The IVS8+4C/T variant appears to be rare in these Asian populations compared to Caucasians, while the IVS8+32 T/C change was found to be common in Asian Indians. Conclusions: The results indicate that OPA1 polymorphisms are not associated with NTG in the Singaporeans, Indians and Japanese.

Keywords: genetics • clinical (human) or epidemiologic studies: risk factor assessment • gene modifiers