Abstract
Purpose: :
The phenotypes of AMD vary by ethnicity, which may reflect differences in genetic risk factors and/or environmental pressures. For instance, PCV has been reported to account for 54.7% of all cases of wet AMD in an Asian population whereas in Whites, PCV is estimated to only make up 8-13%. Therefore, the aim of this research is to provide further understanding of the genetic factors of AMD (PCV, CNV) in Asians.
Methods: :
We conducted a case-control GWAS of PCV and CNV in a clinical cohort of AMD cases using ethnic matched controls from a population based study (Singapore Prospective Study Program) of Chinese participants. The diagnoses of CNV and PCV were made based on fundus examination, fluorescein angiography and indocyanine green angiography findings.
Results: :
This cohort comprised 247 individuals with wet AMD (121 PCV and 126 CNV) (mean age = 68.63 yrs (PCV), 72.95 yrs (CNV)). Controls for analysis were >55 years of age and had normal fundal images (N=154; mean age = 62.33 yrs). Analyses were performed on direct genotyped SNPs only. No association reaching genome-wide significance (p<5x10-8) was found. However, several SNPs across the genome showed suggestive associations (p-values between 5x10-4 and 5x10-8) in areas harbouring genes involved in pathways that may affect or are known to affect the eye, including: CRIM1 and COL4A4 (chr 2), LIFR and Homer1 (chr 5), RP1L1 (chr 8), PTPRD (chr 9), MAP2K6 (chr 17) and ABCG1 (chr 21). Of the known genes associated with wet AMD, SNPs in the HTRA1 gene showed high suggestion for association with CNV (leading SNP: rs3750847; p = 1.69 x 10-6; additive OR: 3.67 [95%CI: 2.16-6.25]) while for PCV, SNPs in CFH showed evidence for association (leading SNP: rs800292; p = 4.13 x 10-4; additive OR: 0.45 [95%CI: 0.29 -0.70]).
Conclusions: :
We replicated associations of previously implicated wet AMD SNPs, particularly those identified in Asian populations. Observed regions of suggestive associations warrant further investigation in order to fully elucidate their involvement in the progression of PCV and/or CNV, especially to understand the AMD phenotype and prevalence differences between ethnicities.
Keywords: genetics • gene mapping • age-related macular degeneration