Choreo-acanthocytosis like phenotype without acanthocytes: clinicopathological case report. A contribution to the knowledge of the functional pathology of the caudate nucleus.

Detailed clinical and neuropathological findings in two unrelated patients with a chorea-acanthocytosis-like phenotype (CA) are reported. One case met all the diagnostic criteria of CA and had a deceased brother with the same disease. The second case had a virtually identical phenotype to the former but without acanthocytes. These findings suggest that both patients are affected by the same disease and that acanthocytes are not essential to the diagnosis. Neuropathological autopsy studies on the brain of the second case showed selective atrophy of the caudate nucleus that seemed to correspond to the movement disorder and behavioural abnormalities prominent in this patient. In both subjects, morphometric and ultrastructural examination of the peripheral nerve showed loss of myelinated fibres, more accentuated distally, and cytoskeletal changes in the axoplasm. These findings support the hypothesis that peripheral neuropathy in CA is caused by distal axonopathy.