Genetic susceptibility to age related macular degeneration

Age related macular degeneration (AMD) is the leading cause of visual impai rment in the elderly and a major cause of blindness in the developed world. The disease can take two forms, geographic atrophy and choroidal neovascul arisation. The pathogenesis of AMD is poorly understood. There are undoubte dly environmental and other risk factors involved and the adverse effect of smoking is well. established. Several studies; have shown that genetic fac tors are important but leave uncertainty about the magnitude and nature of the genetic component and whether it varies with the type of AMD. Several h ereditary retinal dystrophies show similarities to AMD and these genes are potential candidate susceptibility genes. Particular interest has focused o n the ABCR gene which is responsible for autosomal recessive Stargardt macu lar dystrophy. it has been claimed that heterozygotes for ABCR mutations ar e predisposed to AMD but the data are conflicting. Studies of the genes res ponsible for autosomal dominant Sorsby fundus dystrophy, Doyne honeycomb re tinal dystrophy, and Best disease have given negative results. In one large AMD family, linkage has been reported to markers in lq25-q31. Recent data suggest that the ApoE epsilon 4 allele may be associated with reduced risk of AMD. A better understanding of the genetic factors in AMD would contribu te to understanding the pathogenesis. If those: at risk could be identified it may be possible to modify lifestyle or develop novel therapies in the p resymptomatic stage to prevent disease or decrease its severity.