Involvement of the Superior Cerebellar Peduncles in GAA-FGF14 Ataxia.

GAA-FGF14 ataxia (SCA27B) is a recently reported late-onset ataxia caused by a GAA repeat expansion in intron 1 of the FGF14 gene. After the clinical observation of superior cerebellar peduncle (SCP) involvement in some affected patients, we sought to verify the prevalence of this finding in our cohort and 4 additional independent cohorts of patients with SCA27B.We performed a retrospective review of the brain MRI scans of a total of 87 patients (median age at MRI 69 years; range 28-88 years) from different independent cohorts to assess the presence of SCP involvement, defined as abnormally high T2 signal along the SCP tract.We observed SCP involvement in 52 patients (52/87; 59.8%) from all the cohorts combined. The finding was replicated at rates ranging from 50% to 62.8% in the cohorts taken separately.SCP involvement in SCA27B is frequent. Its detection may facilitate the diagnostic process of patients with SCA27B.