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Study identifies potential biomarker for SIDS, but that’s just the start

About 3,400 babies die of SIDS in the United States each year. There is no immediate or obvious cause of death, according to the US Centers for Disease Control and Prevention. Experts don’t know which babies are at risk for SIDS or what causes it.
For their study, published May 6 in the journal eBioMedicine, researchers measured levels of an enzyme called butyrylcholinesterase (BChE) in blood samples from 67 newborn babies who died of SIDS and other unknown causes between 2016 and 2020. They compared these levels with those in the blood of 655 babies in a control group and found that infants who died of SIDS had significantly lower levels of BChE than either living infants or those who died of other causes.

SIDS usually occurs when a child is sleeping. Experts have speculated that it is associated with problems in the part of an infant’s brain that controls breathing and waking. BChE is an enzyme of the cholinergic system, part of the autonomic system, which controls functions such as blood pressure and respiration. The study authors say more research is needed to determine whether BChE tests might be able to identify and prevent future cases of SIDS.

Smoking during pregnancy is one of the risk factors for SIDS, along with factors such as family history and premature birth. The researchers noted that animal studies have shown a link between second-hand smoke and lower BChE. However, many other changes during the first six months of life are also likely to affect these enzymes and the nervous system in general.

The researcher who led the study, Dr Carmel Harrington, an honorary researcher at Children’s Hospital Westmead in Australia, lost her own child to SIDS 29 years ago, according to the Sydney Children’s Hospitals Network.

“Babies have a very powerful mechanism for letting us know when they are unhappy. Usually, if a baby is faced with a life-threatening situation, such as difficulty breathing during sleep because they are on their stomach, they wakes up and cries. . What this research shows is that some babies don’t have that same robust arousal response,” Harrington told the network.

Harrington said this study shows that BChE is involved in this lack of arousal.

“Now that we know BChE is involved, we can start to change the fate of these babies and make SIDS a thing of the past,” she said.

Limitations of the study include that the blood samples were more than two years old, so the results do not reflect BChE activity in fresh blood. The researchers also used coroners’ diagnoses rather than autopsy results and included data on children between the ages of 1 and 2, although SIDS is generally defined as involving a child under the age of one.

Dr. Rachel Moon, chair of the American Academy of Pediatrics SIDS Task Force, noted the study’s small sample size and said the results are not definitive.

“Although the differences in blood levels of this enzyme are statistically different – even if confirmed by larger additional studies – there is enough overlap in blood levels between cases and controls that it cannot be not be used as a blood test at this point with reasonable predictive value,” she said.

Dr. Gabrina Dixon, director of advancing diversity in academic pediatrics at Children’s National in Washington, said the study was interesting, “but I wouldn’t call it a thing yet. It could be promising for research. future, but that’s such a small number of the kids in this study, you need a lot more numbers to say that’s what it is.”

First Candle, a national organization focused on ending sleep-related infant deaths and supporting families, welcomed the research but also urged caution.

“It’s progress, and for that we have to be optimistic, but it’s not the complete answer,” CEO Alison Jacobson said in a statement. “Our concern with the development of a SIDS vulnerability test is that parents have a false sense of security and engage in unsafe sleep practices.”

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