The autosomal-dominant macular dystrophies known as North Carolina macular dystrophy and central areolar pigment epithelial dystrophy were originally described as distinct disease entities in three separate families. However, these disorders have several phenotypic features in common. The single large family with North Carolina macular dystrophy, which descended from three Irish brothers in 1790, has undergone extensive genealogic studies expanding the kindred to more than 2000 family members. As a result, two previously described families with central areolar pigment epithelial dystrophy have been found to descend from these same three Irish brothers with North Carolina macular dystrophy and, therefore, also have North Carolina macular dystrophy. This helps simplify the nosology of the disease and expands the phenotype of North Carolina macular dystrophy to include choroidal neovascular membranes.