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Genetic mutation linked to sudden infant death, study finds

Researchers find possible connection between genes controlling breathing muscle function and some cases of SIDS
Image: A baby sleeps in a crib
Parents who put their babies to sleep on their backs can reduce the risk of SIDS.pinstock / Getty Images-iStockphoto

A rare genetic mutation may provide a clue to sudden infant death syndrome, or SIDS, according to a new study by a group of researchers from the US and UK.

The genetic mutations that impair breathing muscles were found to be more common in children who died of SIDS than healthy babies, according to Dr. Michael Ackerman, co-author of the study and professor of genomics and heritable cardiovascular diseases in sudden death at the Mayo Clinic in Rochester, Minnesota.

The study, published Wednesday in The Lancet, looked at mutations in the SCN4A gene, which is vital to normal lung development. Mutations in this gene are associated with a range of genetic neuromuscular disorders that affect muscle tone, movement and function, which can lead to life-threatening pauses in breathing and spasms of the vocal cords.

“Our study is the first to link a genetic cause of weaker breathing muscles with sudden infant death syndrome, and suggests that genes controlling breathing muscle function could be important in this condition,” says co-author Professor Michael Hanna, of the MRC Centre for Neuromuscular Diseases and UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery in London.

Typically, these mutations are rare — they were found in fewer than five people in every 100,000 — but mutations of this kind were found in four of the 278 children who had died of sudden infant death syndrome, compared to none of the 729 healthy babies. However, the doctors were clear that it's not the sole cause of SIDS and babies who don't have the mutation may still be at risk.

SIDS experts say it's a hopeful finding.

"Every time we identify one of these risks, we identify a possible cause and that allows us to identify more babies at risk and provide solutions that might help them,” said Dr. Joel L. Bass, chair of the department of pediatrics at the Newton Wellesley Hospital and professor of pediatrics at Harvard Medical School.

About 3,500 babies in the United States die suddenly and unexpectedly each year, according to the Centers for Disease Control and Prevention.

"If there’s any hope for families, it’s that the loss of their child might lead to more research that can help prevent the loss of another child."

Causes of SIDS, increasingly referred to as Sudden Unexplained Infant Death (SUID), may include brain abnormalities or accidental suffocation. The inability of babies to regulate their breathing is thought to be another cause. A third of SUID deaths are unexplained.

While there are treatments for children and adults with genetic neuromuscular disorders caused by the SCN4A gene mutations, "it is unclear whether these treatments would reduce the risk of sudden infant death syndrome," said Hanna.

The researchers did not recommend routine genetic testing for the mutation.

“The authors note that these are rare genetic mutations, however we know that SUID is not a rare event, unfortunately," said Dr. Lori B. Feldman-Winter, professor of pediatrics at the Cooper Medical School of Rowan University in Camden, New Jersey. "So we need to continue to push the envelope of research to identify and understand the causes of SUID.”

Because the study included only Caucasian babies of European ancestry, Feldman-Winter noted that it's difficult to generalize the results. "But it is a reminder that more research needs to be done to identify causes that we can prevent,” she said.

While SUID is a frightening possibility, an individual baby’s risk is low.

To protect babies under age 1, the American Academy of Pediatrics recommendations include:

  • Supine positioning, or putting babies to sleep on their back
  • A firm sleep surface
  • Sharing a room with parents, but not bed-sharing
  • Breastfeeding
  • Use of a pacifier at nap time and bedtime
  • Daily supervised, awake tummy time

Parents are also advised to remove infants from car seats, strollers, swings, infant carriers, and infant slings if they fall asleep in them to reduce the risk for gastroesophageal reflux and positional plagiocephaly, or flattening of the head.

“A baby should be sleeping on their back, that’s really important for parents to remember,” said Feldman-Winter. “Mothers should also be encouraged to breastfeed for at least 6 months and avoid smoking during and after pregnancy."

By identifying possible genetic links to SIDS, future deaths may be prevented, Bass said.

“SIDS is a silent, lonely tragedy," said Bass. "If there’s any hope for families, it’s that the loss of their child might lead to more research that can help prevent the loss of another child."