Huntington’s disease‐like 2 and apparent ancestry

Abstract

To the Editor: We readwith interest the paper of Santos et al. (1) reporting the first Huntington’s disease-like 2 (HDL2) patient from Brazil who appeared initially tonot havedirectlyAfricanancestry.Wewould like to draw attention to the fact that a Brazilian patient with HDL2 was reported in abstract form (2). The family of this patient initially alsodenied anAfrican ancestry, nevertheless after thorough evaluation, a probable African ancestor was later found (3). As a significant proportion (44.6%) of the Brazilian population has African ancestry (4), it is probable that the allele (CTG)47-(GACA) came from an unknown African ancestor. To try and clarify this problem, we wonder whether it would be useful to perform the insertion/deletion polymorphisms’ method in the relatives of the patient’s father, verifying whether the polymorphisms found are more suggestive of an African ancestry. Besides these two cases, three other Brazilian families have been identified to date (5), suggesting that HDL2 may be the most important cause of the HDL phenotype in HD-negative patients in Brazil, similar to that reported in the African population (6). This study reports a patient with confirmed HDL2 and an intermediate CAG expansion on Htt gene. This illustrates that HDL2 may occur in patients with non-pathological expansions on Htt gene. Cases previously described as having HD with intermediate expansions (7, 8) are likely to have other illnesses caused by mutations in other genes.