North Carolina macular dystrophy phenotype in France maps to the MCDR1 locus

To determine if a family in France, which manifests an autosomal dominant macular dystrophy, has North Carolina macular dystrophy (MCDR1) and to determine its possible molecular genetic relationship with the original North Carolina family. A family from Northern France with a macular dystrophy underwent comprehensive ophthalmic examinations and were ascertained for genetic studies. Blood collection and examinations were performed on 38 individuals. Fundus photographs with a hand held KOWA camera were obtained on affected subjects. DNA was extracted and genotyping performed using new microsatellite genetic markers, which have recently been found in the MCDR1 (North Carolina macular dystrophy) region. Standard two - point linkage and haplotype analysis was performed. Eleven individuals were found with the clinical manifestations of North Carolina macular dystrophy. Two - point linkage analysis generated a maximum peak LOD score of 4.5 with a recombination of 0% between D6S1717 and the macular dystrophy locus in the French family. The haplotype associated with the disease is, however, different from that of the original North Carolina family. These findings indicate that the macular dystrophy gene in this French family maps to the same region as that of North Carolina macular dystrophy (MCDR1) locus but that independent mutations are involved. The disease in the French family is clinically and genetically similar to North Carolina macular dystrophy. Therefore MCDR1 occurs in various ethnic groups, is present world-wide, and there remains no evidence of genetic heterogeneity for this clinically distinct form of macular degeneration.