THE risk of cot death may be increased by the presence of a rare genetic mutation which affects breathing muscles, researchers have said.
The study, published in The Lancet, raises for the first time the possibility of a genetic link to sudden infant death syndrome (SIDS), one of the leading causes of infant mortality.
Carried out by experts in Britain and the United States, the research focused on the SCN4A gene which affects the breathing muscles, thought to play an important role in explaining cot deaths.
Mutations of this gene are typically found in fewer than five people in every 100,000.
In a study of 278 children who died of cot death, researchers found four cases of the mutation, while there were none in a parallel group of 729 healthy controls.
“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,” said Professor Michael Hanna of MRC Centre for Neuromuscular Diseases at University College London.
“However, more research will be needed to confirm and fully understand this link,” said Hanna, one of the authors of the study.
The gene provides instructions to an important cell surface receptor in the breathing muscles, whose activity is low at birth but which increases over the first two years of life.
Mutations in this gene can cause a range of genetic neuromuscular disorders, as well as life-threatening pauses in breathing and vocal chord spasms that can make breathing temporarily difficult.
SIDS is the unexplained death of a seemingly healthy child within the first year of life, typically affecting babies two and four months old.
It is the leading killer of babies of up to a year, and is said to account for some 2,400 deaths per year in the United States and around 300 in Britain.
The study only looked at infants of European ancestry, and the authors stressed the need to duplicate the study with other ethnic groups in which the suspect SCN4A mutation may be more or less common.
The gene is almost certainly not the sole cause of death, they said, emphasising that safe sleeping measures were still essential to ensure babies' safety.
Previous research has shown that urging parents to put babies to sleep on their backs helped drive down the death rate in the United States from 120 per 100,000 live births in 1992 to 56 per 100,000 in 2001 — a 53 per cent reduction in one decade.
That advice still stands, the authors said.