Stargardt disease:: Linkage to the ABCR gene region on 1p21-p22 in Scandinavian families

Stargardt disease (STGD) or fundus flavimaculatus (FFM) is one of the most frequent causes of macular degeneration in childhood. The disease is inherited as an autosomal recessive trait and the corresponding gene has been localized to chromosome 1p21-22 and subsequently identified as the ATP-binding cassette transporter (ABCR) gene. Purpose: To characterize Finnish and Swedish STGD families genetically, with special reference to chromosome region 1p21-22. Methods: We performed genetic linkage and haplotype analyses in five families of Finnish and Swedish origin with members affected by STGD or FFM. Results: Evidence for linkage between STGD and the ABCR gene region on chromosome 1p was found with a maximum cumulative two-point lod score for marker D1S188 (Z=4.04, theta=0.001). The affected individuals of all families, including the offspring of a consanguineous family, were found heterozygous for haplotypes spanning the ABCR gene. Conclusion: The results support genetic homogeneity for a STGD/FFM gene defect on chromosome 1p21-22. A variety of haplotypes tightly linked to the ABCR gene region were found among affected individuals which indicate the presence of several independent STGD mutations in the Scandinavian population.