Mapping of a distal form of spinal muscular atrophy with upper limb predominance to chromosome 7p

An autosomai dominant distal form of spinal muscular atrophy mainly affecting the upper limbs with a mean age of onset of 17 years has been identified in a large Bulgarian family. Linkage of the above family to the spinal muscular atrophy type I, II and III locus on chromosome 5 has been excluded. In an attempt to map this disease gene we have analysed individuals of this family, with more than 140 microsatellite polymorphic markers of the human genome. A maximum lod score of 5. 99 at θ = 0. 007 has been obtained with locus D7S795. We have thus mapped the gene for this hereditary form of distal spinal muscular atrophy to chromosome 7p.