Abstract
1) Background: CFH and HTRA1 genes are traditional markers of increased risk of AMD across populations. Recent findings suggest that additional genes, for instance, in the dystrophin-associated protein complex might be promising markers for AMD. 2) Methods: Here, we performed a case-control study to assess the effect of SGCD single nucleotide polymorphisms (SNPs), a member of this protein family, on AMD diagnosis and phenotype. We performed a case-control study of 134 cases with 134 unpaired controls. Cases were 60 years or older (CARMS grade 4-5, as assessed by experienced ophthalmologists following the AAO guidelines), without other retinal disease or history of vitreous-retinal surgery. Controls were outpatients aged 60 years or older, with no drusen or RPE changes on fundus exam and negative family history of AMD. We examined SNPs in the SGCD gene: rs931798, rs140617, rs140616, and rs970476 by sequencing and RT-PCR. Genotyping quality check and univariate analyses were performed with PLINK v.1.9. Furthermore, logistic regression models were done in SAS v.9.4 and haplotype configurations in R v.3.3.1. 3) Results: After adjusting for clinical covariates, the G/A genotype of the SGCD gene (rs931798) significantly increases the odds of being diagnosed with AMD in 81% (1.81, 95%CI 1.06-3.14, p=0.031), especially the geographic atrophy phenotype (1.82, 95%CI 1.03-3.21, p=0.038) compared to the G/G homozygous. Moreover, the GATT haplotype in this gene (rs931798, rs140617, rs140616, and rs970476) is associated with lower odds of AMD (Adjusted OR 0.13, 95%CI 0.02-0.91, p=0.041). 4) Conclusions: SGCD is a promising gene for AMD research. Further corroboration in other populations is warranted.