US scientists have discovered more genetic mutations that appear to be linked with cot death.
More research is still needed say the researchers
Like those previously discovered, the errors lie in genes involved with involuntary body functions like heart beat and breathing.
They were more common in cot death babies, particularly those of African American descent, the Rush University team found in its study of 184 babies.
The findings are in the journal Pediatric Research.
This should further scientists' understanding of the causes of sudden infant deaths, say the authors.
Official figures, to be released on Thursday, are expected to show that although the number of cot deaths is falling in the UK, hundreds of infants are still dying unexpectedly.
Scientists have previously found gene mutations related to the brain chemical serotonin were more common in babies with sudden infant death syndrome (SIDS) than healthy babies.
Serotonin influences many different systems in the body, including the part of the nervous system that is concerned with the control of involuntary bodily functions.
It is thought these involuntary systems might malfunction in babies who die from cot death.
Dr Debra Weese-Mayer and colleagues focused their attention on genes crucial to the embryo to develop this 'involuntary' or autonomic part of the nervous system.
They compared the genetic material of 92 cot death babies and 92 healthy babies.
They found 11 gene mutations in 14 of the cot death babies but only one of these mutations in two of the healthy babies.
Nearly three-quarters of the cot death babies who had these mutations were African American, which Dr Weese-Mayer said might explain in part the higher rate of SIDS noted in some ethnicities.
"These data represent further refinement of the genetic profile that might place an infant at increased risk for SIDS," she said.
The researchers said similar mutations had also been in a condition called congenital central hypoventilation syndrome where there is a failure of the body's autonomic nervous system control over breathing while asleep.
The voluntary control over breathing, which operates during waking hours, is generally intact in this condition.
Dr Weese-Mayer and colleagues recommended further research to better understand how these genes might contribute to SIDS.
Joyce Epstein, director of the Foundation for Sudden Infant Deaths, said the findings supported the notion that genetic variations in the parts of the brain that control breathing and arousal from sleep might account for why some babies are at increased risk of SIDS.
"We welcome these new research findings, which help contribute to our understanding of the possible genetic bases of sudden infant death.
"Sudden infant death remains the main kind of death in babies over one month old, and much more medical research is needed, in order to find the causes and prevention of these terrible tragedies," she said.