La choréo-acanthocytose (ChAc) est une maladie autosomique récessive caractérisée par une association de mouvements anormaux, de troubles psychiatriques et cognitifs et d’acanthocytes présents au frottis sanguin. Nous présentons une observation de ChAc pour laquelle des acanthocytes n’ont pas pu être retrouvés.

Un homme, âgé de 26 ans, aux parents consanguins, présentait depuis deux ans une chorée généralisée et des mouvements dystoniques orofaciaux aboutissant à des difficultés d’alimentation et à des lésions de la langue et des lèvres. Il existait un déclin cognitif et des troubles du comportement. L’IRM cérébrale montrait une atrophie du striatum. Le bilan biologique retrouvait une élévation des CPK et LDH. Malgré l’absence d’acanthocytes sur plusieurs frottis sanguins, l’analyse en western blot de la choréine a montré un taux effondré, en faveur d’une ChAc.

Plusieurs observations de ChAc sans acanthocytes ont été rapportées. Des problèmes techniques à la détection des acanthocytes, surtout si la procédure standardisée établie récemment n’est pas respectée, peuvent être suspectés, mais il est important de savoir que la présence d’acanthocytes n’est pas obligatoire pour poser le diagnostic de ChAc.

Chorea-acanthocytosis (ChAc) is one of the neuroacanthocytosis syndromes which form a group of disorders characterized by the association of neurological abnormalities and spiculated red blood cells called acanthocytes. ChAc patients exhibit involuntary movements, psychiatric abnormalities and progressive cognitive deterioration. We report a case of ChAc in which blood smears failed to demonstrate acanthocytes.

A 26-year-old man presented since two years with hyperkinetic movements. The family history was non contributive, parents were consanguineous. Neurological examination revealed choreatic hyperkinesia and dystonia, predominant in the orofacial region. Mild cognitive decline and behavior abnormalities were noted with repetitive activities. Brain MRI showed striatal atrophy. Molecular testing for Huntington’s disease was negative. Routine biological screening was normal except for elevated CPK and LDH. Copper and ceruloplasmin blood levels were normal, as well as purine metabolism and lipoproteins. Further screening for metabolic diseases showed no significant abnormality. Expression of Kell antigens was normal. In several blood smears no acanthocytes were seen. Electromyographic studies showed slight neuropathic changes. Despite the absence of acanthocytes, chorein western blot was performed on blood samples which revealed an absent or markedly reduced level of chorein in erythrocyte membranes. A mutation of the ChAc gene was thus likely so the diagnosis of ChAc was retained. Genetic studies for VPS13A are pending.

ChAc is an autosomal recessive disorder due to mutations of the VPS13A gene coding for chorein. Absence or late appearance of acanthocytes in ChAc has been described in a few case reports. In conclusion ChAc is a rare disorder in which the presence of acanthocytes is not mandatory. In case of doubt, chorein western blot can be useful.