SCYL1 and Gait ataxia: The marked neurological phenotype and cranial MRI abnormalities of thepreviously published patients with SCYL1 variantsare in line with the Scyl1-deficient mouse, which has been known as mdf (muscledeficient) mouse since 1980.17,32 It is affected by progressive gait ataxia, cerebellar vermis atrophy,Purkinje cell loss, and optic nerve thinning.33,34 The previously published patients developed cerebellar dysfunctionduring early childhood.