Sensory ataxia as a prominent clinical presentation in three families with mutations in CYP7B1

Pathogenic mutations in CYP7B1 account for SPG5, an autosomal recessive hereditary spastic paraplegia characterized by a complex phenotype including visual problems and cerebellar dysfunction. Sensory ataxia is not usually regarded as a typical clinical feature of SPG5. The purpose of this study was to describe six patients showing features of sensory ataxia as the prominent and/or initial symptoms of SPG5. Six patients from three distinct pedigrees (three women, three men; age 49.5 ± 18.2 years), all presenting gait unsteadiness and frequent falls since childhood, underwent clinical and molecular investigations. All showed marked sensory ataxic gait with positive Romberg's sign, as well as severely impaired position and vibration sense. Comparatively minor signs of pyramidal involvement were also detected. In four of the patients, brain MRI showed white matter hyperintensities on T2-weighted images. An already reported homozygous c.889A>G (p.T297A) mutation in SPG5/CYP7B1 was found in five patients from two families, whereas the remaining case harbored the novel c.250_251delC/p.L84Ffs*6 and c.266A>C/p.Y89S variants. Marked and enduring sensory ataxia can be a pivotal sign in SPG5, and expands the phenotypic spectrum associated with mutations in CYP7B1.