Abstract
<title>Abstract</title> <p> Background Spinocerebellar ataxia 27B (SCA27B) is an autosomal dominant, late-onset cerebellar ataxia caused by an intronic <italic>FGF14</italic> GAA•TTC repeat expansion and frequently associated with cerebellar atrophy. In this study, we aimed to quantitatively determine whether the cerebellar atrophy in SCA27B is predominantly localized to some sub-cerebellar regions and can be detected on clinical MR studies. Methods We analyzed 3D and/or sagittal T1-weighted MR images from 13 subjects with SCA27B (median age: 67 years, IQR: 9 years, 2 females; median GAA size 383) and 52 age- and sex-matched controls. Cerebellar segmentation was performed using the DeepCERES pipeline. For each region of interest, we calculated mean volume, standard deviation, and relative volume differences between groups. Analysis of covariance (ANCOVA) was used to test the effect of disease status on the volumes while adjusting for age and sex. Results The volume was significantly reduced in all regions of interest (at least − 10%) when compared to controls, except the whole white matter, lobules I–II and IX. The greatest relative volume difference was seen in lobules IV (-25%), VI (-18%), and X (-18%). Lobules IV and X, the grey matter and the whole cerebellum showed the greatest effect of disease status. Conclusions SCA27B is associated with diffuse cerebellar atrophy with relatively important involvement of lobules IV and X. Automated segmentation tools such as DeepCERES enable reliable volumetric characterization from clinical MRI and may support future comparative studies of SCA27B and other forms of late-onset ataxias. </p>