Malignant McLeod myopathy.

Mild myopathy is a common manifestation of the X-linked McLeod neuroacanthocytosis syndrome. We present a patient with McLeod syndrome and a primarily subclinical myopathy, who developed severe rhabdomyolysis with renal insufficiency after a prolonged period of excessive motor restlessness due to an agitated psychotic state and a single dose of clozapine. Other possible causes for rhabdomyolysis such as prolonged immobility, trauma, hyperthermia, generalized seizures, toxin exposure, or metabolic changes were excluded. Clinical course was favorable, with persistent slight elevation of serum creatine kinase levels caused by the underlying myopathy. Our findings suggest that McLeod myopathy is a predisposing factor for severe rhabdomyolysis. This possibly life-threatening condition should be added to the clinical spectrum of McLeod syndrome, and serum creatine kinase levels should be carefully monitored in patients with this syndrome, particularly if a hyperkinetic movement disorder is present or neuroleptic medication is used.