More than 400 Nav1.5 mutations have been discovered and they are implicated in a wide variety of cardiac diseases—including PFHB1A (progressive familial heart block 1A), LQT3, BRGDA1, SSS1, VF1 (familial paroxysmal ventricular fibrillation 1), SIDS (sudden infant death syndrome), ATRST1 (atrial standstill 1), CMD1E (cardiomyopathy, dilated 1E), ATFB10 (atrial fibrillation, familial, 10), and MEPPC (multifocal ectopic Purkinje-related premature contractions) (Fig. 5B and Table 6). The gene discussed is SCN5A; the disease is sudden infant death syndrome.