A form of SIDS (crib death) has been linked to a recessive gene in Amish populations.
BBC – 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.
It opens up the possibility that mutations in other genes may also contribute to some sudden infant deaths.
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.
It also raises questions about the cases in which multiple SIDS deaths in a family have led to murder charges. From a Slate article on the Noe case in which 8 children allegedly died of SIDS…
…experts now believe that losing one baby to SIDS does not increase the likelihood that a family will lose another. However, Wecht points out, there have been cases of two and three unexplained infant deaths in a family in which homicide was ruled highly unlikely. Parents of SIDS babies have been wrongly accused in the past. And most troubling, as I said before, we don’t know what SIDS is in the first place. We may have lumped several different diseases together in describing the syndrome. Perhaps multiple natural deaths in a family are possible.
Indeed. A simple recessive defect carried by both parents would produce statistical odds of one in four children being affected. And as probabilities are extremely unreliable in small samplings, the chances of two or three SIDS cases from two carrier parents would be pretty good.
And those are the odds for simple autosomal recessive mutations. If there are other gene defects that predispose children to crib death that are incompletely dominant (meaning that a single copy of the mutation can cause death, but a minority of carriers are spared and survive to reproduce), half of their children would inherit the defect. If a simple recessive, such as the TSPYL gene is survivable through fetal management and monitoring, 100% of the children of survivors would inherit it.
Prediction: In recent years, the recommended practice of laying infants on their backs to sleep has reduced SIDS deaths dramatically. This may mean that some SIDS deaths are purely mechanical – or it may be that the position compensates for respiratory problems in children with a mild underlying gene defect..If the latter is true, expect a sharp increase in SIDS deaths in a decade or two, when the survivors move into adulthood to have children of their own.