repeated paroxysmal attacks of muscle pain and weakness followed by passage of dark red-brown urine, diagnosed by demonstration of myoglobin in the urine; it is attributed to abnormal phosphorylase activity in skeletal muscle, but there may be more than one biological type; it is more common in males than females; the genetics is obscure. In some cases, at least, there is deficiency of palmitoyl transferase. Syn: familial paroxysmal rhabdomyolysis.