Acanthocytes (acanthos = thorny or spiny in Greek language) are mature red blood cells with multiple protrusions or spicules, often with terminal bulbs, which are irregular in shape, orientation, and distribution. Consequently, acanthocytosis is defined as an increased amount of such misshaped erythrocytes in peripheral blood. Acanthocytes should not be present in the peripheral blood, but in some general and neurological conditions, such as uremia, advanced hepatic disease, post-splenomegaly, advanced malnutrition or spur cell anemia, significant elevations of acanthocyte levels are reported (Brin, 1993; Stevenson & Hardie, 2001). The association of acanthocytosis with neurological syndromes is found in at least three hereditary neurological disorders that are generally referred to as neuroacanthocytosis syndromes (Table 59.1). The first recognized association was that of “malformation of the erythrocyte” in a sporadic case of progressive ataxia and pigmentary retinopathy by Bassen and Kornzweig in 1950 (Bassen & Kornzweig, 1950), but the underlying inherited metabolic abnormality of abetalipoproteinemia with secondary vitamin E deficiency was established years ago. Since then two other fairly distinct syndromes have emerged: the McLeod syndrome and autosomal recessive chorea-acanthocytosis.

Chorea-acanthocytosis (ChAc)

Chorea-acanthocytosis (ChAc; also referred to as Critchley–Levine syndrome; OMIM #200150) is a multisystem degenerative neurological disorder associated with acanthocytosis in the absence of any lipid abnormalities. ChAc was first described in the late 1960s by Estes and co-workers (1967) as well as by Critchley et al. (1968) and Levine et al. (1968) in two American kindreds with very similar features.