First Potential Biomarker for Sudden Infant Death Syndrome Identified

A new study has identified a biomarker that could  one day be used to help babies at higher risk of sudden infant death syndrome (SIDS).

The research, conducted by a team from the Children's Hospital at Westmead (CHW) in Australia, was published in eBioMedicine.

Half of Western infant deaths caused by SIDS

SIDS is defined as the death of an apparently healthy baby that is younger than a year old during sleep. Cases of SIDS have halved in recent years after high-profile campaigns highlighted some of the other risk factors for SIDS, including:

·        Sleeping on their stomach or side

·        Sharing the same bed as a parent

·        Overheating during sleep

Nevertheless, SIDS remains the cause of nearly half of neonatal deaths in Western countries, and biochemical signatures explaining individual babies’ risk of SIDS have been lacking. The new study, led by CHW research fellow Dr. Carmel Harrington hopes to have changed that.

Harrington and team analyzed dried blood spots (DBS) taken during a newborn screening program, using samples that parents had consented to being analyzed.

The study focused on an enzyme called butyrylcholinesterase (BChE). The enzyme has an important function in the arousal pathway, which governs the brain’s level of alertness during wakefulness. The team analyzed BChE levels in samples taken from four different groups:

·        Infants who had died from SIDS (n=26)

·        Infants who had died from non-SIDS causes (n=30)

·        Controls for the SIDS group – healthy infants matched for date of birth and gender (n=254)

·        Controls for the non-SIDS group – healthy infants matched for date of birth and gender (n=291)

The SIDS group showed a significant decline in BChE activity as compared to matched controls, a finding not seen in non-SIDS deaths.

Reduced wakefulness

The team believe that the BChE deficit could indicate a reduced ability to wake in response to stressors in the external environment. Harrington commented in a press release: “Usually, if a baby is confronted with a life-threatening situation, such as difficulty breathing during sleep because they are on their tummies, they will arouse and cry out. What this research shows is that some babies don’t have this same robust arousal response.”

Harrington, who tragically lost her own son, Damien, to SIDS nearly 30 years ago, said that the finding pointed towards a brighter future for babies at risk of SIDS. “This has long been thought to be the case, but up to now we didn’t know what was causing the lack of arousal. Now that we know that BChE is involved we can begin to change the outcome for these babies and make SIDS a thing of the past,” she said.

Nevertheless, the small sample size involved is an indicator that the research remains at an early stage and parents are still encouraged to take steps to minimize environmental risk factors for SIDS. CHW’s Child Health Promotion Unit says that babies should be placed on their backs to sleep with their head and face uncovered during the night. Additionally, a baby’s household should be smoke-free.

The next step for the research is a five-year study that will incorporate the BChE biomarker into screening of newborns. The team are planning efforts to mitigate the biochemical effects of the enzyme deficiency.

Harrington, who has crowdfunded much of her research through a campaign called Damien’s Legacy, concluded, “This discovery changes the narrative around SIDS and is the start of a very exciting journey ahead. We are going to be able to work with babies while they are living and make sure they keep living.”

Reference: Harrington CT, Hafid NA, Waters KA. Butyrylcholinesterase is a potential biomarker for Sudden Infant Death Syndrome. eBioMedicine. 2022;80:104041. doi: 10.1016/j.ebiom.2022.104041