EVIDENCE OF GENETIC-HETEROGENEITY OF LEBERS CONGENITAL AMAUROSIS (LCA) AND MAPPING OF LCA1 TO CHROMOSOME 17P13

Leber's congenital amaurosis (LCA) is an autosomal recessive disease r esponsible for congenital blindness. It is the earliest and most sever e inherited retinal dystrophy in human and its genetic heterogeneity h as long been recognised. We have recently reported on the first locali sation of a disease gene (LCA1) to the short arm of chromosome 17 by h omozygosity mapping in five families of North African origin. Here, we refine the genetic mapping of LCA1 to chromosome 17p13 between loci D 17S938 and D17S1353 and provide strong support for the genetic heterog eneity of this condition (maximum likelihood for heterogeneity, 17.20 in InL; heterogeneity versus homogeneity, P = 0.0002, heterogeneity ve rsus no linkage, P < 0.0001).