P2.05: are Retinal Microvascular Phenotypes Associated with 1675G/A Polymorphism in Angiotensin Ii Receptor-2 Gene?

Background The X-linked AT2R G1675A polymorphism is located in the short intron 1 of the AT2R gene within a sequence motif conforming to a splice branch site. AT2R is expressed in the human retina, but no previous study examined the association between retinal microvascular phenotypes and the AT2R G1675A polymorphism. Methods In 340 subjects randomly selected from a Flemish population (mean age, 51.9 years; 51.5% women), we post-processed retinal images (Canon CrDGi) using IVAN software to generate the retinal arteriole and venule equivalents (CRAE and CRVE) and the arteriole-to-venule-ratio (AVR). DNA fragments including the AT2R G1675A, AT1R A1166C, ACE I/D and CYP11B2 C– 344T polymorphisms, were amplified by PCR. We applied a mixed model to assess phenotype-genotype associations while accounting for relatedness and covariables. Results CRAE, CRVE and AVR averaged 151.9 µm, 215.2 µm and 0.710, respectively. CRAE was 5.5 µm greater in women than men and decreased with age ( P <0.05). In multivariable-adjusted analyses, CRAE was higher in hemizygous and homozygous carriers of the AT2R A allele than in their G allele counterparts in both sexes combined (+4.49 µm; P = 0.014) and in men (+4.91 µm; P = 0.032) with a similar trend in women (+3.41 µm; P = 0.14). AVR was increased in the presence of the AT2R A allele compared with AT2R G hemizygotes and homozygotes (+0.024; P = 0.0082). The associations of CRAE and CRVE with other polymorphisms was not significant. Conclusions: Pending confirmation in experimental and epidemiological studies, our findings suggest that diameter of the retinal arterioles might be associated with the AT2R 1675G/A polymorphism.