[A case of McLeod syndrome].

A 52-year-old man was admitted to our hospital in 1997 because of high serum creatine kinase (CK) level. Neurologic findings revealed chorea on the trunk and extremities, mild weakness of proximal muscles, and absence of deep tendon reflexes in four extremities. Serum CK was elevated to 3,494 U/l (normal, below 235). A peripheral blood smear showed acanthocytes in approximately 1% of the red blood cells (RBCs). Very weak expression of the Kell antigens (K2, K4, K5, and K7) on his RBCs led us to make a final diagnosis of McLeod syndrome. Muscle biopsy from the left biceps showed increased variability in fiber diameter, a few regenerating fibers, scattered fibers with internal nuclei, and mild fiber type grouping. Immunohistochemical analyses of dystrophin. merosin, and adhalin were normal. Although McLeod syndrome is a rare X-linked recessive disorder, it is clinically important for differential diagnosis of chorea acanthocytosis and hyperCKemia.