Age-related macular degeneration-associated variants at chromosome 10q26 do not significantly alter ARMS2 and HTRA1 transcript levels in the human retina

PURPOSE Multiple studies demonstrate a strong association between three variants at chromosome 10q26 - rs10490924, del443ins54, and rs11200638 - near the age-related maculopathy susceptibility 2 (ARMS2) and high-temperature requirement factor A1 (HTRA1) genes with susceptibility to age-related macular degeneration (AMD). In different reports, the del443ins54 and rs11200638 variants are suggested to affect ARMS2 mRNA stability and/or HTRA1 mRNA expression, respectively. The goal of this study is to examine whether these AMD-associated variants alter expression levels of ARMS2 and HTRA1 in human retina samples. METHODS Genomic DNA and total RNA were obtained from 35 human retinas (three young controls, average age=32 years; twenty aged controls, average age=72 years; and twelve AMD retinas, average age=77 years) using standard procedures. As ARMS2 exhibits higher expression in the human placenta, we also included eighteen placenta samples in our analysis. Four polymorphisms - rs2736911, rs10490924, del443ins54, and rs11200638 - were genotyped by PCR followed by sequencing. Expression of ARMS2, HTRA1 and three endogenous control genes (rRNA [rRNA], hypoxanthine phosphoribosyltransferase 1 [HPRT1], and glyceraldehyde-3-phosphate dehydrogenase [GAPDH]) was measured by real-time quantitative RT-PCR using Taqman gene expression or SYBR Green assays. RESULTS ARMS2 and HTRA1 mRNA levels did not show a significant difference in expression among the control (young and elderly) and AMD retinas. No association of del443ins54 and rs11200638 variants was detected with mRNA expression levels of ARMS2 or HTRA1 in the retina. Human placenta samples showed high variability in expression levels. CONCLUSIONS We did not find association between AMD susceptibility variants at 10q26 and steady-state expression levels of either ARMS2 or HTRA1 in the human retina.