McLeod syndrome: A novel mutation, predominant psychiatric manifestations,and distinct striatal imaging findings

The McLeod syndrome is an X-linked disorder caused by mutations of the XK g ene encoding the XK protein. The syndrome is characterized by absent Kx ery throcyte antigen, weak expression of Kell blood group system antigens, and acanthocytosis. In some allelic variants, elevated creatine kinase, myopath y, neurogenic muscle atrophy, and progressive chorea are found. We describe a family with a novel point mutation in the XK gene consisting of a C to T base transition at nucleotide position 977, introducing a stop codon. Amon g seven affected males, five manifested with psychiatric disorders such as depression, bipolar disorder, or personality disorder, but only two present ed with chorea Positron emission tomography and magnetic resonance volumetr y revealed reduced striatal 2-fluoro-2-deoxy-glucose (FDG) uptake and dimin ished volumes of the caudate nucleus and putamen that correlated with disea se duration. In contrast, none of 12 female mutation carriers showed psychi atric or movement disorders. However, a semidominant effect of the mutation was suggested by erythrocyte and blood group mosaicism and reduced striata l FDG uptake without structural abnormalities. Therefore, patients with psy chiatric signs or symptoms segregating in an X-linked trait should be exami ned for acanthocytosis and Kell/Kx blood group serology.