Distal muscular dystrophies are a group of slowly progressive diseases with adult onset, characterized by distal muscle involvement of upper and lower limbs.
There are two main forms:
1. Welander Muscular Dystrophy, an autosomal dominat disorder showing weakness at the hand muscles at onset and progressing slowly with distal muscle involvement of lower limbs.
2. Miyoshi Myopathy, recessively inherited showing distal muscle involvement of lower limbs and then progressing with weakness at proximal muscles of upper limbs. The main molecular defects of these disorders fall within the DYSF gene, responsible for the dysferlin protein expression.