US scientists have discovered a genetic disorder that appears to be linked with some cot deaths.
Genetic disorder might explain some cot deaths
The culprit gene was carried in the Amish community, but might also occur in the general population, say Dr Dietrich Stephan and colleagues.
This could account for some previously unexplained deaths, according to the Translational Genomics Research Institute team.
Their findings appear in Proceedings of the National Academy of Sciences.
Cot death is a term commonly used to describe a sudden and unexpected infant death that is initially unexplained.
Sometimes the cause is found. Cot deaths that remain unexplained are usually registered as sudden infant death syndrome (SIDS).
Doctors do not know why these babies die.
Other genes have been associated with unexplained infant deaths.
Dr Stephan and colleagues believe some of these babies die from a genetic disease they have named
sudden infant death with dysgenesis of testes (SIDDT).
They looked at 21 infants who had died suddenly and came from two generations of an American Amish community.
All died before 12 months of age from sudden cardiac and respiratory arrest.
Dr Stephan's team looked at the genes of four of these infants and found a defect common to all them.
All four infants had two abnormal copies of a gene called TSPYL which is located on chromosome 6.
The researchers looked at DNA from the parents of each of the children and found the parents carried only one abnormal copy of the gene.
The researchers believe having two abnormal copies of TSPYL affects the nervous system and causes sudden death by interfering with the brain's control of the heart and lungs.
Male babies born with these genes also had underdeveloped testes, they found.
Dr Stephan said: "There's a whole class of SIDS that is totally unexplained. This is one of the first gene mutations that subclassifies those babies. SIDDT will account for a certain proportion of SIDS.
"More gene mutations that account for SIDS are going to follow in the next few years.
"At the end of this process we are going to be able to diagnose at birth if a baby has one of these disorders and hopefully intervene.
He said the next step was to work out how common this mutation was in the general population.
"The Amish population in the US has a very high frequency of genetic diseases because of their population structure and cultural beliefs.
"But all of the disorders that are present in the Amish communities are also present in the general population, just at a lower frequency, both in the US and in the UK," he said.
Professor George Haycock from Foundation for the Study of Infant Deaths (FSID) said: "This is a highly original and important piece of research, and it's the first clear demonstration that mutations in a gene can cause cardio-respiratory instability and death in infancy. It opens up the possibility that mutations in other genes may also contribute to some sudden infant deaths. "