Serum serotonin levels elevated in some cases of sudden infant death syndrome

It’s new parents’ worst nightmare: Their child dies suddenly in his or her sleep, and doctors can’t pinpoint a cause. According to the Centers for Disease Control & Prevention, approximately 1,600 children in the U.S. died in 2015 from this so-called sudden infant death syndrome (SIDS), which doctors believe is a range of disorders. Now a team led by Robin L. Haynes and Hannah C. Kinney of Boston Children’s Hospital and Harvard Medical School reports that nearly one-third of SIDS cases they studied had elevated levels of serotonin in their blood serum (Proc. Natl. Acad. Sci. USA 2017, DOI: 10.1073/pnas.1617374114). Previous studies by some of the same researchers found reduced levels of the neurotransmitter in the brain stems of about 40% of SIDS cases. “If these abnormalities coexist in the same infants, then we would identify these infants as having a global problem in serotonin production or serotonin-related function,” Haynes says. The next step is to determine the underlying mechanism of the abnormal serotonin levels and whether serum serotonin can be used as a biomarker for identifying at-risk babies. Such infants might be identified as having a “serotonopathy” rather than SIDS, Haynes says. With such studies, she adds, scientists will slowly replace the SIDS label with underlying disease processes.