Sudden infant death syndrome (SIDS) is the sudden death of an infant that is not predicted by medical history and remains unexplained after a thorough forensic autopsy. About 3,500 US infants die suddenly and unexpectedly each year. SIDS is the leading cause of death among infants 1 month to 1 year old, and claims the lives of about3,500 each year in the United States. Approximately 95% of all SIDS cases occur before the age of 6 months and infants are at the highest risk for SIDS during sleep. A lack of answers is part of what makes sudden infant death syndrome (SIDS) so frightening.
SIDS has been attributed to numerous mechanisms such as respiratory problems and infectious diseases. Aside from respiratory problems, cardiac problems are thought to contribute to the development of SIDS. Recent studies suggest that approximately 1 out of 10 SIDS case may be due to genetic mutations that change the flow of ions through the heart cells. These ion channel defects would alter the action potential of the heart resulting in the development of certain types of life threatening arrhythmias.
The first direct evidence linking SIDS to a congenital heart defect was published in The New England Journal of Medicine in 2000 based on work done by our team at the MMRL in collaboration with clinical colleagues in Italy. A mutation in the gene known as SCN5A was shown to produce a major increase in late sodium current providing the first demonstration that a life-threatening event, with all of the features of SIDS, may be due to a cardiac ion channel mutation.
Recently, we have published several articles describing how the electrical and contractile properties of the heart develop as a function of age. A better understanding of the circumstances and events associated with sleep-related infant deaths may help reduce future deaths. This information will guide us in better understanding the basis for fatal cardiac arrhythmias contributing to SIDS.