An autopsy case of sudden unexpected nocturnal death syndrome with R1193Q polymorphism in the SCN5A gene.

SCN5A (sodium channel, voltage-gated, type V, alpha subunit) gene encodes the cardiac sodium channel, a member of the voltage-gated sodium channel family. SCN5A mutations have been associated with a variety of inherited arrhythmias, including long QT syndrome and Brugada syndrome. We report an autopsy case of sudden unexpected nocturnal death syndrome. A man in his thirties died at night while sleeping. At autopsy, no traumatic injury, disease or drug intake was observed as a possible cause of death. We examined mutations in the SCN5A gene and identified a heterozygous mutation causing an R1193Q amino acid substitution. It was reported that the R1193Q polymorphism in the SCN5A gene destabilizes channel inactivation and may be a risk factor for Brugada and long QT syndrome. It may be considered that the cause of death in this case was sudden cardiac death.