XK and cardiomyopathy: McLeod syndrome (MLS) is a rare progressive disease, an X-linked multisystem disorder encoded by the XK gene, with central nervous system, neuromuscular, cardiovascular, and hematological clinical manifestations that may include progressive chorea-like movements, cardiomyopathy, peripheral neuropathy, and cognitive decline accompanied by comorbidities such as psychosis (Wilcox et al., 1986).