North Carolina macular dystrophy: Hereditäre Makulaerkrankung mit guter funktioneller Prognose -- a hereditary macular dystrophy with good visual prognosis

Background: North Carolina macular dystrophy (NCMD) is a rare autosomal dominant maculopathy with highly variable expressivity. Genetic analysis of an American family consisting of 247 members out of which 96 were affected with NCMD allowed chromosomal assignment of the NCMD locus to 6q14-q16.2. Few families with NCMD are known in Europe, one of these is living in Germany. By routine investigation, a second family affected with NCMD was detected in Germany. As some authors still doubt the good prognosis of this disease, our results should be added to the experience of others. Patients and methods: In a total of 18 family members from three generations between the age of 2 and 65 years, clinical investigations and genetic analysis was carried out. Some individuals had additional examinations such as colour contrast sensitivity, EOG, ERG, and microperimetry. Results: Ten of 18 family members turned out to be affected. All grades of NCMD were present with great variability. Visual acuity ranged from 0.32 to 1.0 and did not correlate to the grade of the disease or to the age of the person. In those patients who underwent microperimetry, central fixation was confirmed. Genetic linkage analysis further narrowed the region harbouring the NCMD locus and supported the assumption that the central areolar pigment epithelial dystrophy (CAPED) is an allelic disorder. Conclusion: Similar visual acuity in three generations of NCMD patients supports the observation that NCMD is not a progressive disorder. If geographic atrophy is found in a patient with good visual acuity, NCMD should be considered and genetic analysis should be carried out.