Although SUDC is less common than SIDS, SUDC has essentially no targeted research funding, Dr. Tsien said. Study coauthor Laura Gould, MA, a researcher and mother who lost a young child to SUDC, worked with Orrin Devinsky, MD, to create a registry for families with cases of SUDC. This registry was instrumental in allowing the researchers to “do the molecular detective work we need to do” to see whether a genetic basis exists for SUDC, Dr. Tsien said.
“The detective work comes up with a consistent story,” he said. “More than half of the genes that we found are involved in the normal function of the heart and brain,” performing such functions as delivering calcium ions to the inside of the heart cells and nerve cells.
The study “is the first of its kind,” given the difficulty of acquiring DNA from the child and two parents in SUDC cases, Dr. Tsien said.
Overall, approximately 10% of the cases have a compelling explanation based on the coding of DNA, Dr. Tsien said. From a clinical standpoint, that information might affect what a clinician says to a parent.
A key takeaway is that most of the genetic mutations are spontaneous and are not inherited from the parents, Dr. Tsien said. The study findings indicate that parents who suffer an SUDC loss need not be discouraged from having children, he added.
For the long term, “the more we understand about these disorders, the more information we can offer to families,” he said. Eventually, clinicians might be able to use genetics to identify signs of when SUDC might be more likely. “For example, if a child shows a very mild seizure, this would alert them that there might be potential for a more drastic outcome.”
Meanwhile, families with SUDC cases may find support and benefit in signing up for the registry and knowing that other families have been through a similar experience, Dr. Tsien said.
Genetic studies create opportunities
A significant portion of pediatric mortality remains unexplained, according to Richard D. Goldstein, MD, of Boston Children’s Hospital. One reason is the lack of a formal diagnostic code to identify these deaths.
Research to date has suggested links between SUDC and a family history of febrile seizures, as well as differences in brain structure associated with epilepsy, Dr. Goldstein said.
“An important hypothesis is that these deaths are part of a continuum that also includes stillbirths, SIDS, and sudden unexpected death in epilepsy [SUDEP],” Dr. Goldstein said. “By mandate, investigations of these deaths occur under the jurisdiction of medical examiners and coroners and have, for the most part, been insulated from developments in modern medicine like genomics and proteomics, elements of what are referred to as the molecular autopsy, and studies such as the current study bring attention to what is being missed.”
Dr. Goldstein said the new study buttresses the “conventional clinical suspicion” about the likely causes of SUDC, “but also strengthens the association between sudden unexpected death in pediatrics (SUDP) and SUDEP that we and others have been positing. I think the researchers very nicely make the point that epilepsy and cardiac arrhythmia genes are not as separated in their effects as many would believe.”
As for the clinical applicability of the findings, Dr. Goldstein said medicine needs to offer parents more: “Pediatric deaths without explanation deserve more than a forensic investigation that concerns itself mostly with whether there has been foul play,” he said. “We need to figure out how to engage families, at an incredibly vulnerable time, in helping find the cause of the child’s death and also contributing to needed research. Most of the reported variants were de novo, which means that parent participation is needed to figure out these genetic factors but also that we can offer reassurance to families that other children are not at risk.”
The study was supported by the SUDC Foundation and Finding a Cure for Epilepsy and Seizures (New York University). Dr. Tsien disclosed support from the National Institutes of Health and a grant from FACES. Dr. Goldstein reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.