Myopathy, Distal, 7, Adult-Onset, X-Linked, is also known as mpd7. An important gene associated with Myopathy, Distal, 7, Adult-Onset, X-Linked is SMPX (Small Muscle Protein X-Linked). Affiliated tissues include skeletal muscle, and related phenotypes are distal lower limb muscle weakness and fatty replacement of skeletal muscle