Investigating the association between OPA1 polymorphisms and glaucoma: comparison between normal tension and high tension primary open angle glaucoma
OPA1, the gene responsible for autosomal dominant optic atrophy, represents a good candidate gene for glaucoma, as there are similarities in the clinical phenotype and OPA1 is expressed in the optic nerve. Single nucleotide polymorphisms on intervening sequence (IVS) 8 of the OPA1gene (genotype IVS8+4 C/T;+32T/C) were recently found to be strongly associated with normal tension glaucoma (NTG). In order to investigate whether this association exists in patients with high-tension glaucoma (HTG), 90 well-characterized HTG patients were examined for the presence of these OPA1 polymorphisms by PCR amplification followed by bi-directional sequencing. Five out of 90 HTG subjects (5.6%; 95% CI 1.8–12.5) were found to carry the OPA1 genotype IVS 8+4 C/T; +32 T/C, compared with 32/163 (19.6%; 95% CI 13.8–26.6) NTG subjects [χ2=9.2, P=0.002, OR 4.1 (95% CI 1.6–11.1)], and 7/186 (3.8%; 95% CI 1.5–7.6) control subjects [χ2=0.47, P=0.49, OR 1.5 (95% CI 0.5–4.9)]. These results indicate that unlike NTG, the OPA1 genotype IVS8+4 C/T,+32T/C is not significantly associated with high-tension primary open angle glaucoma, and suggest genetic heterogeneity between the conditions.