Nearly 3,000 babies a year die suddenly in their sleep in the U.S., leaving devastated parents wondering what went wrong. Findings published online this week in the Proceedings of the National Academy of Sciences offer insight into the genetic basis of one type of sudden infant death syndrome (SIDS). This is one of the first genetic sub-classifications of SIDS, says study leader Dietrich A. Stephan of the Translational Genomics Research Institute (TGen) in Phoenix, Ariz. And it's going to be helpful in offering parents answers for sudden infant deaths, recognizing predisposition early, and hopefully saving a number of these babies.

The researchers identified children who suffered from a specific form of SIDS known as SIDDT in an Amish community in Pennsylvania. Twenty-one infants from nine families had passed away before the age of one and the scientists analyzed DNA from four of the babies as well as their parents, siblings and close relatives. The researchers identified an alteration in a gene on chromosome 6 called TSPYL: all four children had two abnormal copies of the gene, and their parents each carried one copy of the alteration. TSPYL is expressed in the brain stem, and sudden deaths may occur because of changes to the brain's regulatory systems that govern cardiac and pulmonary protective reflexes, the team reports. The researchers will next investigate the relationship between TSPYL mutations and SIDS in the general population, as well as the gene's role in controlling breathing and heart rate in premature infants that are otherwise normal.