The presence of peripheral blood film acanthocytes can help narrow the differential diagnosis of a familial choreiform disorder. Acanthocytosis is associated with chorea–acanthocytosis (ChAc), McLeod syndrome, pantothenate kinase-associated neurodegeneration (PKAN), and Huntington’s disease-like 2 (HDL-2).1 Huntington disease (HD) can present at a similar age with a similar phenotype, but without acanthocytosis. We report the cases of three adult siblings with genetically confirmed ChAc, and discuss the unusual finding of a co-existing abnormal HD allele (CAG repeat expansion in the range of reduced penetrance) in two of these siblings.