AP4S1 and cerebellar ataxia: While pyramidal signs were almost universally present, gait/posture problems were frequently reported in most genotypes except for SPG9, SPG12, SPG28, SPG43, and SPG64. Ataxia was highly prevalent in SPG7, SPG12, SPG28, SPG43, SPG44, SPG46, SPG50, SPG52, and SPG79, among others.