Distal myopathies

Distal myopathies are classified according to clinical, histopathological, and genetic patterns into the following: late adult onset type 1, or Weland er myopathy, the first recognized distal myopathy with autosomal dominant i nheritance and very recently linked to chromosome 2p; late adult onset type 2, or Markesbery-Griggs/Udd myopathy, autosomal dominant with linkage to c hromosome 2q; early adult onset type 1, or Nonaka myopathy, an autosomal re cessive disease linked to 9p1-q1 and considered indistinguishable from here ditary, inclusion body myopathy; early adult onset type 2, or Miyoshi myopa thy, with autosomal recessive inheritance linked to chromosome 2p12-p14; an d early adult onset type 3, or Laing myopathy, autosomal dominant with link age to chromosome 14. Very recently, dysferlin, a novel skeletal muscle gen e, has been found mutated in Miyoshi myopathy and also in the limb girdle m uscular dystrophy 2B, a disease with a completely different phenotype. This indicates that the classification of the distal and other genetically dete rmined muscle diseases will probably change when these myopathies are under stood at the molecular level. For example, it would be reasonable to use th e term dysferlinopathies to describe all the diseases due to dysferlin muta tions.