Small-expanded allele spinocerebellar ataxia 17: imaging and phenotypic variability.

Federico Paolini Paoletti, Paolo Prontera, Pasquale Nigro, Simone Simoni, Giulia Cappelletti, Marta Filidei, Paolo Calabresi, Lucilla Parnetti, Nicola Tambasco

Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology 2021 Oct

filter terms:

Spinocerebellar ataxia 17 (SCA17) is a rare genetic cause of adult-onset ataxia caused by an abnormal expansion of the CAG/CAA sequence in the TATA-box Binding Protein (TBP) gene. A number of repeats higher than 49 are full penetrance-expanded. The range between 41 and 49 repeats is characterized by decreased penetrance, and it is usually referred to as "small." Here, we describe two patients with the SCA17 phenotype and with 43 and 44 CAG repeats in the TBP gene, and review all the previously reported cases of SCA17 with a small range of expansions. We focus on both clinical features and imaging findings, which, in the case of small-expanded alleles, can resemble those of atypical parkinsonisms. Thus, we suggest to consider the small-expanded allele SCA17 as a possible diagnosis in patients with adult-onset ataxia, even when both clinical and imaging characteristics are suggestive for other non-genetic neurodegenerative diseases. © 2021. Fondazione Società Italiana di Neurologia.

Citation

Federico Paolini Paoletti, Paolo Prontera, Pasquale Nigro, Simone Simoni, Giulia Cappelletti, Marta Filidei, Paolo Calabresi, Lucilla Parnetti, Nicola Tambasco. Small-expanded allele spinocerebellar ataxia 17: imaging and phenotypic variability. Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology. 2021 Oct;42(10):4309-4315