NORTH-CAROLINA MACULAR DYSTROPHY (MCDR1) IN TEXAS

Purpose: To map the gene responsible for causing a macular degeneratio n in a Texan family that appears clinically similar to the North Carol ina macular dystrophy (MCDR1) phenotype. Methods: A single family in T exas had all the typical clinical features of the North Carolina macul ar dystrophy phenotype. Of 23 family members examined, 10 were affecte d. Blood was collected from all 23 members and fundus photographs were obtained on those affected. A detailed family history consisting of n ine generations was obtained. Genotyping and likelihood analysis was p erformed using the closest linked MCDR1 markers. Results: The genealog ic data showed no relation with the original North Carolina macular dy strophy pedigree. The dinucleotide repeat marker D6S283 yielded the hi ghest 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 li nkage results indicate that the macular degeneration in this Texan fam ily is due to a mutation in the same genomic region as that causing No rth Carolina macular dystrophy. Furthermore, haplotype analysis sugges ts that the original North Carolina family and the Texan family have t he same mutation and a common founder.