Objective: To identify the chromosomal location of the gene involved in the pathogenesis of autosomal dominant radial drusen (malattia leventinese).
Patients: Eighty-six members of four families affected with radial drusen; one family of American origin and three families of Swiss origin.
Methods: Family members were clinically examined for the presence of radial drusen. Affected patients and potentially informative spouses were genotyped with short tandem repeat polymorphisms distributed across the autosomal genome. The clinical and genotypic data were subjected to linkage analysis.
Results: Fifty-six patients were found to be clinically affected. Significant linkage was observed between the disease phenotype and markers known to lie on the short arm of chromosome 2. The maximum two-point lod score (Zmax) observed for all four families combined was 10.5 and was obtained with marker D2S378. Multipoint analysis yielded a Zmax of 12, centered on marker D2S378. The lod-1 confidence interval was 8 cM, while the disease interval defined by observed recombinants was 14 cM.
Conclusions: The gene responsible for autosomal dominant radial drusen has been mapped to the short arm of chromosome 2. This is an important step toward actually isolating the disease-causing gene. In addition, this information can be used to evaluate other familial drusen phenotypes such as Doyne's macular dystrophy for a possible allelic relationship.