Dataset Information

HTRA1 variants in exudative age-related macular degeneration and interactions with smoking and CFH.

ABSTRACT: Mapping the genes for age-related macular degeneration (AMD) had not been successful until recent genome-wide association studies revealed Tyr402His in CFH and rs11200638 in HTRA1 as AMD-related genetic variants. This study was conducted to identify other critical factors in HTRA1 that are associated with exudative AMD.The promoter, splice regions, and coding exons of HTRA1 were sequenced in 163 patients with exudative AMD and 183 sex- and age-matched control subjects. Also documented were the CFH genotype and smoking status.Four significant SNPs were found in the promoter and the first exon of HTRA1: rs11200638 (-625G>A), rs2672598 (-487T>C), rs1049331 (102C>T, Ala34Ala), and rs2293870 (108G>T, Gly36Gly) with respective P = 1.7 x 10(-14), 3.0 x 10(-10), 3.7 x 10(-12), and 3.7 x 10(-12). Among them, rs11200638 is the most significant associated SNP with a high odds ratio (OR) of 7.6 (95% CI: 3.94-14.51). One risk haplotype block across the promoter and exon 1, ACCTT, significantly predisposes to AMD (P = 6.68 x 10(-14)). In both models, significant independent additive effects were identified with smoking and rs800292 (184G>A, Val62Ile) of CFH. Smoking and rs11200638 (HTRA1) combined caused a 15.7-fold increased risk, whereas combined rs800292 and rs11200638 caused a 23.3-fold increased risk. An extremely high population attributable risk (PAR) of 78% was also found.A high impact of the additive effect of CFH and HTRA1 in the development of exudative AMD was shown. The HTRA1-smoking additive effect found in this study further suggests the importance of this environmental risk factor in AMD.

SUBMITTER: Tam PO

PROVIDER: S-EPMC3215269 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature

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HTRA1 variants in exudative age-related macular degeneration and interactions with smoking and CFH.

Tam Pancy O S PO Ng Tsz Kin TK Liu David T L DT Chan Wai Man WM Chiang Sylvia W Y SW Chen Li Jia LJ DeWan Andrew A Hoh Josephine J Lam Dennis S C DS Pang Chi Pui CP

Investigative ophthalmology & visual science 20080303 6

<h4>Purpose</h4>Mapping the genes for age-related macular degeneration (AMD) had not been successful until recent genome-wide association studies revealed Tyr402His in CFH and rs11200638 in HTRA1 as AMD-related genetic variants. This study was conducted to identify other critical factors in HTRA1 that are associated with exudative AMD.<h4>Methods</h4>The promoter, splice regions, and coding exons of HTRA1 were sequenced in 163 patients with exudative AMD and 183 sex- and age-matched control subj ...[more]

PMID: 18316707

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Project description:BACKGROUND: Age-related macular degeneration (AMD) is the major cause of blindness in the elderly. Those with the neovascular end-stage of disease have irreversible loss of central vision. AMD is a complex disorder in which genetic and environmental factors play a role. Polymorphisms in the complement factor H (CFH) gene, LOC387715, and the HTRA1 promoter are strongly associated with AMD. Smoking also contributes to the etiology. We aimed to provide a model of disease risk based on these factors. METHODS AND FINDINGS: We genotyped polymorphisms in CFH and LOC387715/HTRA1 in a case-control study of 401 patients with neovascular AMD and 266 controls without signs of disease, and used the data to produce genetic risk scores for the European-descent population based on haplotypes at these loci and smoking history. CFH and LOC387715/HTRA1 haplotypes and smoking status exerted large effects on AMD susceptibility, enabling risk scores to be generated with appropriate weighting of these three factors. Five common haplotypes of CFH conferred a range of odds ratios (ORs) per copy from 1 to 4.17. Most of the effect of LOC387715/HTRA1 was mediated through one detrimental haplotype (carriage of one copy: OR 2.83; 95% confidence interval [CI] 1.91-4.20), with homozygotes being at particularly high risk (OR 32.83; 95% CI 12.53-86.07). Patients with neovascular macular degeneration had considerably higher scores than those without disease, and risk of blinding AMD rose to 15.5% in the tenth of the population with highest predicted risk. CONCLUSIONS: An individual's risk of developing AMD in old age can be predicted by combining haplotype data with smoking status. Until there is effective treatment for AMD, encouragement to avoid smoking in those at high genetic risk may be the best option. We estimate that total absence of smoking would have reduced the prevalence of severe AMD by 33%. Unless smoking habits change or preventative treatment becomes available, the prevalence of AMD will rise as a consequence of the increasing longevity of the population.

Project description:PurposeVariants in complement factor H (CFH), the hypothetical LOC387715, and the high-temperature requirement A-1 (HTRA1) genes have been reported to be associated with age-related macular degeneration (AMD). The purpose of this study was to investigate the association of reported common single-nucleotide polymorphisms (SNPs) in CFH, LOC387715, and HTRA1 with exudative AMD in a northern Chinese population.MethodsA cohort of 121 unrelated patients with exudative AMD and 132 control subjects were enrolled in this study. Genomic DNA was extracted from blood leukocytes. Genotyping for SNPs rs1061170:T>C in CFH (Y402H), rs10490924:G>T in LOC387715 (A69S), and rs11200638:G>A in the promoter of HTRA1 was performed using a polymerase chain reaction (PCR) method followed by allele-specific restriction enzyme digestion and direct sequencing.ResultsThe Y402H variant in CFH was not associated with exudative AMD in our study population. Frequencies of Y402H was 10.3% in AMD cases and 8.0% in controls (p=0.353). Significant associations were detected for exudative AMD with SNPs rs10490924:G>T in LOC387715 (A69S), and rs11200638:G>A in the promoter of HTRA1. The risk T-allele frequency of rs10490924 in LOC387715 was 64.9% in cases versus 43.2% in controls (p<0.001). The odds ratio for risk of AMD was 1.56 (95% CI; 0.80-3.03) for the GT genotype and 5.45 (95% CI; 2.59-11.49) for the TT genotype. The A allele frequency of rs11200638 in the HTRA1 promoter was 67.8% in cases versus 42.4% in controls (p<0.001). The odds ratio was 2.75 (95% CI; 1.34-5.64) for the GA genotype and 7.90 (95% CI; 3.61-17.26) for the AA genotype. An odds ratio of 7.94 (95% CI; 3.49-18.04) was obtained for carriers with both TT genotype in LOC387715 and AA genotype in the HTRA1 promoter.ConclusionsOur data suggest that the LOC387715 and HTRA1 polymorphisms are associated with a higher risk of exudative AMD in northern Chinese. We found no association of CFH Y402H with exudative AMD. The low frequency of CFH Y402H variant was further confirmed in this study population.

Project description:BackgroundSingle-variant associations with age-related macular degeneration (AMD), one of the most prevalent causes of irreversible vision loss worldwide, have been studied extensively. However, because of a lack of refinement of these associations, there remains considerable ambiguity regarding what constitutes genetic risk and/or protection for this disease, and how genetic combinations affect this risk. In this study, we consider the two most common and strongly AMD-associated loci, the CFH-CFHR5 region on chromosome 1q32 (Chr1 locus) and ARMS2/HTRA1 gene on chromosome 10q26 (Chr10 locus).ResultsBy refining associations within the CFH-CFHR5 locus, we show that all genetic protection against the development of AMD in this region is described by the combination of the amino acid-altering variant CFH I62V (rs800292) and genetic deletion of CFHR3/1. Haplotypes based on CFH I62V, a CFHR3/1 deletion tagging SNP and the risk variant CFH Y402H are associated with either risk, protection or neutrality for AMD and capture more than 99% of control- and case-associated chromosomes. We find that genetic combinations of CFH-CFHR5 haplotypes (diplotypes) strongly influence AMD susceptibility and that individuals with risk/protective diplotypes are substantially protected against the development of disease. Finally, we demonstrate that AMD risk in the ARMS2/HTRA1 locus is also mitigated by combinations of CFH-CFHR5 haplotypes, with Chr10 risk variants essentially neutralized by protective CFH-CFHR5 haplotypes.ConclusionsOur study highlights the importance of considering protective CFH-CFHR5 haplotypes when assessing genetic susceptibility for AMD. It establishes a framework that describes the full spectrum of AMD susceptibility using an optimal set of single-nucleotide polymorphisms with known functional consequences. It also indicates that protective or preventive complement-directed therapies targeting AMD driven by CFH-CFHR5 risk haplotypes may also be effective when AMD is driven by ARMS2/HTRA1 risk variants.

Dataset Information

HTRA1 variants in exudative age-related macular degeneration and interactions with smoking and CFH.

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HTRA1 variants in exudative age-related macular degeneration and interactions with smoking and CFH.

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