Most people believe that sudden infant death syndrome (SIDS) is a "sleep accident." But a new study published Wednesday in JAMA Network Open suggests that genetics may play a role in the condition, Adrianna Rodriguez writes for USA Today.

Cheat sheet: Infant health inequity

What you need to know about SIDS

SIDS is unexplained death of a baby that is under a year old and is seemingly healthy, according to the Mayo Clinic. Typically, SIDS occurs when an infant is sleeping and is sometimes called "crib death," Rodriguez writes.

According to Boston Children's Hospital, SIDS falls into a larger category of unexpected infant deaths called sudden unexpected death in infancy (SUDI), which includes deaths that can later be explained.

During the first year of life, SIDS is the leading cause of natural death, with roughly 3,400 unexpected deaths in the U.S. every year, according to CDC.

Still, the condition remains a "medical mystery." While scientists do not know what causes SIDS, Mayo Clinic noted that the condition could occur for several reasons, including:

• Physical factors, including brain defects, low birth weight, and respiratory infections that contribute to breathing problems
• Sleep environmental factors, including certain sleeping positions that hinder an infant's ability to breathe properly, sharing a bed, or overheating

A new study suggests genetics may play a role in SIDS

For the study, researchers in Denmark identified 2,384 younger siblings of 1,540 infants who died from SIDS between January 1978 and December 2016.

After a year, eight of the younger siblings died of SIDS at a median age of 2.5 months. Most SIDS cases occurred during the first six months of life, with 61% occurring among males.

Over a period of 39 years, the researchers found that siblings of infants who died of SIDS had a fourfold increase in risk of dying from SIDS themselves when compared with the general population.

In addition, the researchers found that siblings of infants who died from SIDS were more likely to live in a household with low income. These infants were also more likely to have mothers with a lower education level than the general population.

The study supports previous research that suggests SIDS may be a medical problem, according to Richard Goldstein, director of the Robert's Program on Sudden Unexpected Death in Pediatrics at Boston Children's Hospital.

"The general bias is that this is a sleep accident and the challenge for people looking at the science here is to advocate on behalf of the families and look harder," Goldstein said.

While this study is not the first to identify a genetic association with SIDS, some experts have argued that there has been a deficit of resources allocated to SIDS research. In fact, a 2021 study published in JAMA Pediatrics found that SIDS is the 12th-most underfunded pediatric condition by the National Institutes of Health.

Experts noted that new evidence continues to support the theory that genetics plays a part in SIDS, underscoring the importance of investing in more research.

"We think there are mechanisms at play that we're on the trail of," Goldstein said. (Rodriguez, USA Today, 1/26; Glinge et al., JAMA Network Open, 1/25)