McLeod syndrome: a neurohaematological disorder.

The X-linked McLeod syndrome is defined by absent Kx red blood cell antigen and weak expression of Kell antigens, and this constellation may be accidentally detected in routine screening of apparently healthy blood donors. Most carriers of this McLeod blood group phenotype have acanthocytosis and elevated serum creatine kinase levels and are prone to develop a severe neurological disorder resembling Huntington's disease. Onset of neurological symptoms ranges between 25 and 60 years, and the penetrance of the disorder appears to be high. Additional symptoms of the McLeod neuroacanthocytosis syndrome that warrant therapeutic and diagnostic considerations include generalized seizures, neuromuscular symptoms leading to weakness and atrophy, and cardiopathy mainly manifesting with atrial fibrillation, malignant arrhythmias and dilated cardiomyopathy. Therefore, asymptomatic carriers of the McLeod blood group phenotype should have a careful genetic counseling, neurological examination and a cardiologic evaluation for the presence of a treatable cardiomyopathy.