ABSTRACT
Neurological abnormalities associated with spiculated, "acanthocytic" red cells in blood have been described as neuroacanthocytosis. This is a heterogeneous group of conditions that can be clearly subdivided on the basis of recent genetic findings. The McLeod Syndrome, one of the core neuroacanthocytosis syndromes, is a rare X-linked disorder caused by mutations of the XK gene, an X-chromosomal gene of unknown function characterized by haemopoietic abnormalities and late-onset neurological and muscular defects. We report two Chilean brothers with the McLeod phenotype who showed important psychiatric features. The diagnosis may be elusive if the presence of acanthocytosis is not properly studied. We describe a method which allowed the diagnosis that unmasked acanthocytosis. Otherwise the condition could have remained undiagnosed as it had been for decades in this family. This syndrome must be considered when assessing a familial movement disorder, specially affecting males with relevant psychiatric features. A reliable test for acanthocytosis assessment is available.