In a Canadian cohort of 157 SPG4 patients from 65 families with different mutations, only one patient had oculomotor abnormalities, involving hypometric saccades, pursuit smooth impairment, and mild horizontal gaze-evoked nystagmus.6In two SPG5A patients out of 105 Italian probands with pure or complex SPG, Arnoldi et al.59identified a complicated form with nystagmus, dysarthria, and sensorineural hearing loss in one and cataract and mild cognitive impairment in the other. This evidence concerns the gene CYP7B1 and pathologic nystagmus.