The Association Of Polymorphisms In Complement Factor H, Factor B, LOC387715/ARMS2 And ERCC6 With Age-related Macular Degeneration In South Australia Population

Age-related Macular Degeneration(AMD)is the most common form of irreversible blindness among patients 50 years and older in developed coutries such as American,Japan and Australia.The clinical hallmark of AMD is the appearance of drusen,localized deposits lying between the basemeng membranes of the retinal pigment epithelium(RPE)and Bruch membrane.The progressive degeneration of central part of retina called the macula leads to the loss of central vision.It is estimated that by the year 2020,the number of individuals having AMD will increased to 3 million.At present,50 million persons are diagnosed as AMD all over the world.AMD is also an important cause of visual impairment of the elderly 60 years and older in China.The pathogenesis of AMD remains unclear.The contemporary view is that AMD is a multifactor disorder stemming from the interaction of multiple genetic factors and environmental risk factors such as advanced age,light exposure,oxidative damage.In 2005,Seddon et al reported that genetic factors play a substantial role in the etiology of AMD and associated macular characteristics,explaining 46%to 71%of the variation in the overall severity of the disease.Twin and population-based aggregation studies have also implicated a hereditary component in the disorder.Recently,a number of studies have identified associations between AMD and some candidate genes.AimsTo investigate the associations between several coding variants,Y402H,in the complement factor H gene(CFH),L9H and R32Q in Complement Factor B(BF),A69S in LOC387715 and C-6530G in ERCC6 and AMD.The interactions of the gene-gene and phenotype-genotype were also investigated.MethodsOne hundred twenty-five South Australian patients with AMD and two hundred seventeen well characterized normal individuals were enrolled in the study.Genomic DNA from white blood cells was extracted.Y402H polymorphism in CFH;L9H,R32Q polymorphisms in BF;A69S polymorphism in LOC387715;and C-6530G polymorphism in ERCC6 were amplified by polymerase chain reaction(PCR),SNaPshot and enzyme digest based assay were developed for rapid PCR based genotyping of the CFH Y402H and ERCC6 C-6530G variants.The L9H polymorphism and R32Q polymorphism in BF,A69S polymorphism in LOC387715 were determined by PCR-restriction fragment length polymorphism analysis.The association between the genetic polymorphisms and the disease was examined by software Epicalc2000.Results1.The frequency of the risk allele,1277C was 65.2%in AMD patients compared with 40.6%in controls(P=0.00000000053).Genotype frequency differed significantly between the two groups(1277TT15.2%, 1277TC39.2%,1277CC45.6%in the AMD group;1277TT36.4%, 1277TC46.1%,1277CC17.5%in the control group;P=0.000000017).On subgroup analysis.The 1277C allele significantly increased the risk for neovascular AMD(wet AMD OR=4.5;95CI=2.9～7.0;dry AMD OR=1.93,95%CI=1.3～2.85)。2.LOC387715 A69S polymorphism was related to AMD with odds ratio (ORs)of 2.64(95%CI=1.82～3.83).The effect was not stronger for wet AMD(OR=2.55;95CI=1.62～4.00)compared with dry AMD(OR= 2.73,95%CI=1.77～4.23)relative to no progression for the homozygous risk state.The disease odds ratio is 34.5(95%CI=3.93～305.94)conferred by homozygosity for risk alleles at both CFH and LOC387715 when compared with the baseline non-risk genotype.3.The frequency of risk alleles,L9H and R32Q in BF was 4.5%in cases and 5.4%in controls(P=0.64)and 5.7%in cases and 10.6%in controls(P =0.13),respectively.4.The frequency of the risk allele G in ERCC6 was 51.8%in AMD patients compared with 47.4%in controls(P=0.35).Genotype frequency was difference between the two groups(CC22.3%,GC51.8%,GG25.9%in the AMD group;CC18.8%,GC67.5%,GG13.7%in the control group;P =0.03).Conclusions1.Y402H in the gene CFH is associated with dry and wet AMD.2.A69S in the gene LOC387715 is related to AMD,a disease odds ratio of 34.5 conferred by homozygosity for risk alleles at both CFH and LOC387715 when compared with the baseline non-risk genotype.3.There is no association between BF and AMD.4.The SNP C-6530G of ERCC6 maybe associatied with AMD.