Abstract
Abstract: :
Purpose: OPA1, the gene responsible for autosomal dominant optic atrophy, represents a good candidate gene for glaucoma as the clinical phenotypes are similar, and OPA1 is expressed in the optic nerve. Single nucleotide polymorphisms on intervening sequence (IVS) 8 of the OPA1 gene (genotype IVS 8 +4 C/T; +32 T/C) were recently found to be strongly associated with normal tension glaucoma (NTG). The aim of this study was to investigate this association in patients with high-tension glaucoma (HTG). Methods: Ninety well-characterized HTG patients were examined for the presence of these OPA1 polymorphisms by PCR amplification followed by bi-directional sequencing. The frequency of the polymorphisms found was compared with that of a cohort of 163 NTG subjects and 186 population controls. The inclusion criteria were the presence of typical glaucomatous optic neuropathy with compatible visual field loss and open angles on gonioscopy. NTG patients had mean IOP without treatment that was consistently less than or equal to 21 mm Hg on diurnal testing, while HTG patients had IOP consistently greater than 21 mm Hg. Hg. Results: A total of 90 HTG patients were included in the study. All patients were Caucasian, and there were 42 (46.7%) females. 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 to 32/163 (19.6%; 95% CI 13.8-26.6) NTG subjects (chi sq= 9.2, p= 0.002, OR 4.1 [95% CI 1.6 to 11.1]), and 7/186 (3.8%; 95% CI 1.5-7.6) control subjects (chi sq=0.47, p=0.49, OR 1.5 [95% CI 0.5 to 4.9]). Conclusion: The OPA1 genotype IVS 8 +4 C/T, +32 T/C, found to be strongly associated with the occurrence of NTG, is not significantly associated with high-tension primary open angle glaucoma. These results suggest underlying genetic heterogeneity between the conditions.
Keywords: 420 genetics • 444 intraocular pressure • 498 optic disc