SCN1A and epilepsy: Four associated genes have been identified: calcium voltage-gated channel subunit alpha 1A (CACNA1A), ATPase Na+/K+ transporting subunit alpha 2 (ATP1A2), sodium voltage-gated channel alpha subunit 1 and proline rich transmembrane protein 2.[1,2] The coexistence with epilepsy accounts for 40% of overall HM patients, and drug-resistant forms of epilepsy are rare in all FHM mutations.[4]