SQTS should be suspected in a newborn who died suddenly, being considered the main cause of death in the first year of life (sudden infant death syndrome—SIDS); genetic analysis identifies pathogenic variants primarily in three genes, KCNQ1, KCNJ2, and KCNH2, in 45% of cases, as recommended by current guidelines [52,61]. The gene discussed is KCNJ2; the disease is sudden infant death syndrome.