CACNA1A and familial hemiplegic migraine: SLE may also complicate the course of other neurological diseases such as channelopathies related to Familial Hemiplegic Migraine (FHM), a paroxysmal neurological disease caused by mutations in CACNA1A (encoding the neuronal pore-forming CaV2.1 channel α1A subunit), ATP1A2 (encoding the Na+, K+-ATPase pump α2 subunit) or SCN1A (encoding the neuronal NaV1.1 channel α1 subunit).