Although hemiplegic migraine (HM) is linked to CACNA1A mutations that enhance CaV2.1 channel activity and EA2, on the contrary, is associated to loss-of-function mutations, symptomatology overlap of HM, EA2 and SCA6 are well recognized at the clinical level (reviewed in [11]). This evidence concerns the gene CACNA1A and familial or sporadic hemiplegic migraine.