Autosomal dominant distal spinal muscular atrophy: an Italian family not linked to 12q24 and 7p14.

Distal spinal muscular atrophy is genetically heterogeneous, as sporadic cases and both autosomal dominant and recessive inheritance have been described. An autosomal dominant distal spinal muscular atrophy with upper limb predominance has been mapped to chromosome 7p, and more recently, an autosomal dominant distal spinal muscular atrophy with lower limb predominance has been linked to chromosome 12q24. We describe a four generation Italian family with autosomal dominant distal spinal muscular atrophy starting between 8 and 30 years with weakness and atrophy of distal leg muscles. The older patients also presented sensorineural deafness. We performed genetic linkage analysis with microsatellite markers D12S366, D12S349, D12S86, D12S321, D12S1612, D12S1349, D12S342, PLA2A on chromosome 12q24 and D7S516, D7S2496, D7S632, D7S2252 on chromosome 7p14. No support for linkage to chromosome 12q24 and 7p14 was found in our family, confirming a genetic heterogeneity within autosomal dominant distal spinal muscular atrophy.