North Carolina macular dystrophy (MCDR1) in Texas

Purpose: To map the gene responsible for causing a macular degeneration in a Texan family that appears clinically similar to the North Carolina macular dystrophy (MCDR1) phenotype. Methods: A single family in Texas had all the typical clinical features of the North Carolina macular dystrophy phenotype. Of 23 family members examined, 10 were affected. Blood was collected from all 23 members and fundus photographs were obtained on those affected. A detailed family history consisting of nine generations was obtained. Genotyping and likelihood analysis was performed using the closest linked MCDR1 markers. Results: The genealogic data showed no relation with the original North Carolina macular dystrophy pedigree. The dinucleotide repeat marker D6S283 yielded the highest 2-point LOD score with a Z(max) = 4.1 at theta = 0. The peak LOD score generated from multipoint analysis was 6.0. Conclusions: The linkage results indicate that the macular degeneration in this Texan family is due to a mutation in the same genomic region as that causing North Carolina macular dystrophy. Furthermore, haplotype analysis suggests that the original North Carolina family and the Texan family have the same mutation and a common founder.