Muscular aspects of chorea-acanthocytosis

Abstract

We report new insights into muscular aspects in chorea-acanthocytosis (ChAc), a hereditary disease characterized by involuntary movements and amyotrophy with elevation of serum creatine kinase (sCK). In addition, we review the literature regarding muscular aspects of genetically-confirmed ChAc cases. All ChAc cases, except for one, showed sCK elevation, while clinical neuromuscular symptoms are variously reported in most. Conventional muscle stains, such as hematoxylin and eosin (H&E), nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR), and ATPase, showed mild neurogenic changes and/or mild myopathic changes. Recently, evidence has accumulated of a primary myopathy in ChAc. Increase of tTGase-derived Nε-(-γ-glutamyl)lysine isopeptide cross-links was shown in skeletal muscle as well as in erythrocytes [19]. It was also reported that nemaline rods were found within myofibres in a patient with ChAc [27]. Moreover, immunohistochemical staining with two specific antibodies against chorein showed distribution changes of the protein in three heterozygous ChAc cases. Although the precise mechanism of the myopathic changes is still unclear, these findings suggest that skeletal muscles as well as peripheral nerves are primarily involved in the pathophysiology of this disorder.