Renin-angiotensin-aldosterone system genes and nonarteritic anterior ischemic optic neuropathy

PURPOSE Recent literature suggests a genetic component for non-arteritic anterior ischemic optic neuropathy (NAION). We examined the association of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme gene, of the M235T polymorphism of the angiotensinogen gene, and of the A1166C polymorphism of the angiotensin II type 1 receptor gene with NAION. METHODS Forty-seven patients with NAION and 76 controls, age- and gender-matched, were recruited and genotyped for renin-angiotensin-aldosterone system (RAAS) genes. Genotypes were determined by polymerase chain reaction and restriction enzyme analysis. NAION and control groups were compared in regard to the prevalence of renin-angiotensin-aldosterone system polymorphisms, and further stratified by age and gender. RESULTS NAION occurrence was not associated with the M235T polymorphism of the angiotensinogen gene and the A1166C polymorphism of the angiotensin II, type 1 receptor gene. Regarding the angiotensin-converting enzyme insertion/deletion polymorphism, our findings suggest that the II genotype could be a risk factor for NAION in younger male patients when compared to all cases and controls (p=0.033, odds ratio=5.71, confidence interval=1.152¨C28.35 and p=0.03, odds ratio=5.33, confidence interval=1.17¨C24.31 respectively). Furthermore I allele was present in all male patients younger than 55 years, making this allele a likely predisposing factor for NAION in young males. CONCLUSIONS Since NAION may occur when compromised watershed microcirculation is combined with insufficient autoregulation of systematic circulation, polymorphisms of genes involved in systematic circulation, such as the RAAS genes, may be associated with NAION occurrence. Large-scale, multicentered, controlled prospective studies are needed to further explore the effects of RAAS polymorphisms or other genetic factors on NAION susceptibility.