RFC1 and cerebellar ataxia: A single oculomotor endpoint sensitive enough to detect changes in the majority of affected patients could be identified only in SCA2 (peak-velocity of horizontal VGS), NPC (peak-velocity of vertical VGS), RFC1-related ataxia (both aVOR gain reduction and DBN were seen in most or even all patients) and SCA27B (DBN seen in all patients).