To tackle these questions we studied the functional consequences of mutations causing familial hemiplegic migraine (FHM), a rare monogenic subtype of migraine with aura, in knock-in mouse models carrying either a FHM type 1 (FHM1) or a FHM type 2 (FHM2) mutation. The gene discussed is CACNA1A; the disease is familial hemiplegic migraine.