Genetic linkage of Welander distal myopathy to chromosome 2p13

Welander distal myopathy (WDM) is an autosomal dominant myopathy with late- adult onset characterized by slow progression of distal muscle weakness. Th e disorder is considered a model disease for hereditary distal myopathies a nd is almost only seen in Sweden and some parts of Finland. A genomewide sc reening has been performed in initially two Swedish families with 400 highl y polymorphic microsatellite markers. We report here that the disease is li nked to chromosome 2p13. Seven additional nonrelated families have subseque ntly been mapped to the same area where a maximum two-point LOD score of 17 .97 was obtained with the marker D2S2113 at 0.0 recombination fraction. The region has been restricted by recombinations and the finding of a common s hared haplotype through all analyzed families. This restricts the gene locu s region to 2.4 cM. These findings provide evidence for the involvement of a single locus for WDM. The WDM region overlaps with the linkage region for Miyoshi myopathy and limb-girdle muscular dystrophy 2B. The dysferlin gene responsible for these disorders is considered a primary candidate gene for WDM.