Best's vitelliform dystrophy (VMD2) maps between D11S903 and PYGM: no evidence for locus heterogeneity

Vitelliform macular dystrophy, also known as Best's disease (BD), is an autosomal dominant disorder typically characterized by an accumulation of yellowish material in the macular area. The disease is slowly progressive and eventually results in atrophy of the retinal pigment epithelium and photoreceptor cells, thus severely impairing central vision. The biochemical defect underlying this condition is unknown. More recently, the BD locus (VMD2) was mapped to chromosome 11 by genetic linkage to microsatellite markers at D11S871 and INT2. In the present study, we report a detailed genetic analysis in three multigeneration Best's disease families using eight microsatellite markers spanning approximately 26 cM around the putative BD locus. We demonstrate linkage between Best's disease and the markers used. Furthermore, haplotype analysis in our unrelated Best's disease families identified three distinct haplotypes associated with the disease, strongly suggesting independent origins of the BD mutation. Finally, we characterized two recombinant BD chromosomes that significantly refine the location of the disease gene to a 3.7-cM interval between markers at D11S903 and PYGM. PCR-hybrid mapping sublocalized this interval to the pericentromeric region of chromosome 11.