Alleles in the HtrA serine peptidase 1 gene alter the risk of neovascular age-related macular degeneration

Abstract

Objective: To examine if the genes encoding the pleckstrin homology domain-containing protein gene (PLEKHA1), hypothetical LOC387715/ARMS2 gene, and HtrA serine peptidase 1 gene (HTRA1) located on the long arm of chromosome 10 (10q26 region) confer risk for neovascular age-related macular degeneration (AMD) in an independent or interactive manner when controlling for complement factor H gene (CFH) genotype and smoking exposure.

Design: Retrospective matched-pair case-control study.

Participants: Hospital clinic-based sample of 134 unrelated patients with neovascular AMD who have a sibling with normal maculae (268 subjects).

Methods: Disease status was ascertained by at least 2 investigators by review of fundus photographs and/or fluorescein angiography according to the Age-Related Eye Disease Study grading scale. If necessary, a home retinal examination was performed (n = 6). A combination of direct sequencing and analysis of 8 highly polymorphic microsatellite markers was used to genotype 33 megabases of the 10q26 region on leukocyte DNA. Smoking history was obtained via a standardized questionnaire and measured in pack-years. The family-based association test, haplotype analysis, multiple conditional logistic regression, and linkage analysis were used to determine significant associations.

Main outcome measure: Neovascular AMD status.

Results: Of the 23 variants we identified in the 10q26 region, 6 were significant. Four of the 6 were novel and included 2 genotypes that reduced risk of AMD. Many single-nucleotide polymorphisms (SNPs), including the previously reported variants rs10490924 (hypothetical LOC387715/ARMS2) and rs11200638 (HTRA1), defined 2 significant haplotypes associated with increased risk of neovascular AMD. The coding HTRA1 SNP rs2293870, not part of the significant haplotypes containing rs10490924 and rs11200638, showed as strong an association with increased susceptibility to neovascular AMD. Linkage analysis supported our findings of SNP association (P<10(-15)). No significant interactions were found between any of the SNPs in the 10q26 and smoking or between these SNPs and CFH genotype.

Conclusions: Independent of CFH genotype or smoking history, an individual's risk of AMD could be increased or decreased, depending on their genotype or haplotype in the 10q26 region.

Figure 1

Ensembl single-nucleotide polymorphisms (SNPs) are shown along the 10q26 region encompassing the pleckstrin homology domain– containing protein gene, LOC387715/ARMS2, and HtrA serine peptidase 1 gene, illustrating the 3 distinct haplotype blocks that were defined by the confidence intervals, an algorithm proposed by Gabriel et al using Haploview. The linkage disequilibrium (LD) (r²) between any 2 SNPs is listed in the cross cell. The darker the color, the higher the LD between any 2 SNPs. kb = kilobase.