Katherine Schon

We present a comprehensive characterization of clinical, neuropathological, and multisystem features of a man with genetically confirmed McLeod neuroacanthocytosis syndrome, including video and autopsy findings. A 61‐year‐old man presented with a movement disorder and behavioral change. Examination showed dystonic choreiform movements in all four limbs, reduced deep‐tendon reflexes, and wide‐based gait. He had oromandibular dyskinesia causing severe dysphagia. Elevated serum creatinine kinase (CK) was first noted in his thirties, but investigations, including muscle biopsy at that time, were inconclusive. Brain magnetic resonance imaging showed white matter volume loss, atrophic basal ganglia, and chronic small vessel ischemia. Despite raised CK, electromyography did not show myopathic changes. Exome gene panel testing was negative, but targeted genetic analysis revealed a hemizygous pathogenic variant in the XK gene c.895C > T p.(Gln299Ter), consistent with a diagnosis of McLeod syndrome. The patient died of sepsis, and autopsy showed astrocytic gliosis and atrophy of the basal ganglia, diffuse iron deposition in the putamen, and mild Alzheimer's pathology. Muscle pathology was indicative of mild chronic neurogenic atrophy without overt myopathic features. He had non‐specific cardiomyopathy and splenomegaly. McLeod syndrome is an ultra‐rare neurodegenerative disorder caused by X‐linked recessive mutations in the XK gene. Diagnosis has management implications since patients are at risk of severe transfusion reactions and cardiac complications. When a clinical diagnosis is suspected, candidate genes should be interrogated rather than solely relying on exome panels.