Spinocerebellar Ataxia Type 27B (SCA27B): A Hereditary Ataxia in Portugal

Spinocerebellar ataxia type 27B (SCA27B) is a recently discovered hereditary disease caused by (GAA)≥250 repeat expansion in the fibroblast growth factor 14 (FGF14) gene, and multiple studies have recognized it as one of the most common causes of autosomal dominant ataxia in the European population. We present the case of a 62-year-old Portuguese patient who developed a slowly progressive gait impairment associated with wide-base ataxic gait, dysarthria, left upper limb dysmetria, and dysdiadochokinesia. This pure cerebellar phenotype had an episodic worsening induced by intense physical activity and alcohol intake. The patient had an older brother with a late-onset cerebellar ataxia of unknown cause. Genetic testing detected a heterozygotic intronic FGF14 repeat expansion with complete penetrance (> 360 repeats), confirming the diagnosis of SCA27B. To our knowledge, we present the first reported case of SCA27B in the Portuguese population.