Distal myopathies are classified according to clinical, histopathological, and genetic patterns into the following: late adult onset type 1, or Welander
myopathy, the first recognized
distal myopathy with autosomal dominant inheritance and very recently linked to chromosome 2p; late adult onset type 2, or Markesbery-Griggs/
Udd myopathy, autosomal dominant with linkage to chromosome 2q; early adult onset type 1, or
Nonaka myopathy, an autosomal recessive disease linked to 9p1-q1 and considered indistinguishable from
hereditary inclusion body myopathy; early adult onset type 2, or
Miyoshi myopathy, with autosomal recessive inheritance linked to chromosome 2p12-p14; and early adult onset type 3, or Laing
myopathy, autosomal dominant with linkage to chromosome 14. Very recently,
dysferlin, a novel skeletal muscle gene, has been found mutated in
Miyoshi myopathy and also in the
limb girdle muscular dystrophy 2B, a disease with a completely different phenotype. This indicates that the classification of the distal and other genetically determined muscle diseases will probably change when these
myopathies are understood at the molecular level. For example, it would be reasonable to use the term dysferlinopathies to describe all the diseases due to
dysferlin mutations.