Researchers have discovered that heart disease caused by genetic mutations account for significantly fewer sudden and unexplained deaths of infants than previously reported.
Investigators looked at hundreds of cases of sudden infant death syndrome (SIDS) - unexplained deaths of an infant less than one year old in the UK and United States and found that mutations that cause heart disease, account for less than five percent of the deaths.
Previous studies indicated that genetic heart mutations may be behind 20 percent of the cases.
SIDS represents up to 80 percent of all sudden unexpected infant deaths with an incidence of four in 1,000 live births in the United Kingdom and five in 1,000 live births in the US. The peak incidence occurs between two months and four months of age and is more common in boys.
Researchers at St George's, University of London and the Mayo Clinic, in Minnesota, used a type of DNA testing called exome sequencing to check for any genetic disorders.
The St George's and Mayo Clinic researchers looked at cases where the average age of the infants was 2.7 months old.
Dr Elijah Behr, Reader in Cardiovascular Medicine, at St George's, University of London, said: "We have established that in most cases there are other causes for these tragic deaths of young children rather than genetic heart mutations.
"There is now every urgency to discover the true cause of these dreadful human tragedies and importantly also indicate any healthcare implications and treatment necessary for relatives, especially siblings."
Co-senior author Dr Michael Ackerman, director of the Mayo Clinic's Long QT Syndrome/Genetic Heart Rhythm Clinic, said: "We now are turning our attention to the genes implicated to other organ systems to determine their potential contribution. In addition, we are now exploring other genetic contributions to SIDS.
"Our results highlight the importance for accurate interpretation of autopsy testing because the results affect the counseling and guidance of surviving family members."