Definition:

Laing distal myopathy (MPD1) is an early onset autosomal dominant distal myopathy. Selective weakness of the anterior tibial muscles is followed by weakness of the finger extensors and of selected proximal muscle groups, such as the abductors and rotators. This disease is caused by mutations in MYH7, the gene encoding the myosin heavy chain, which is expressed in type 1 fibers of skeletal muscle and in the heart.