Prevalence of Optineurin Mutations in Adults with Primary Open Angle Glaucoma in Ghana, West Africa

Abstract

Abstract: : Purpose: Sequence variants in the gene coding for optineurin (OPTN) have been associated with primary open angle glaucoma (POAG) (Rezaie et al., Science, 2002). The predominant phenotype in individuals with reported variations in OPTN has been normal–tension glaucoma (NTG). Two OPTN variants have been observed in multiple probands: the disease allele E50K which substitutes a glutamate for a lysine at codon 50 and the risk–associated allele M98K which substitutes a methionine for a lysine at codon 98. The purpose of this study is to investigate the prevalence of OPTN in patients with POAG in Ghana, West Africa. Methods: The Ghana Ministry of Health and the Duke University IRB approved the protocol for this study. Informed consent was obtained from all study subjects. Duke investigators (PC,LWH,RRA) screened patients for POAG at the Emmanuel Eye Clinic in Accra, Ghana. POAG was defined as the presence of glaucomatous optic neuropathy in the absence of any secondary causes. Age and sex–matched unaffected controls were obtained in patients with an IOP < 22 mmHg and normal appearing optic nerves. DNA was extracted from blood samples from affecteds and controls. Exons 4 and 5, containing the E50K and M98K alleles were sequenced and screened using standard PCR amplification and sequencing protocols. Results: One hundred and forty–eight unrelated affecteds with POAG and 96 controls were recruited. No E50K mutations were found in affecteds or controls. The M98K risk–associated allele was found in 29.1% of affecteds and 27.1% of controls. The difference was not statistically significant (p= 0.738). Conclusions: Reported variations in OPTN do not appear to play a significant role in the genetic etiology of POAG in this West African population. These results are similar to findings by other investigators and further support the contention that polymorphisms of OPTN are not associated with the pathogenesis of high tension POAG. Screening of remaining exons of OPTN is in progress.

Keywords: gene screening • genetics • intraocular pressure