GM mice to help unravel mystery of cot death

12 September 2012

A baby

Researchers at the MRC's National Institute for Medical Research (now part of the Francis Crick Institute) have developed the first reliable animal model of Sudden Infant Death Syndrome (SIDS, or 'cot death'). The research has uncovered a direct link between low oxygen, abnormal heart changes and sudden death in apparently healthy newborns.

"SIDS is still a substantial medical problem," explained researcher Dr Ross Breckenridge. "Since the reduction in death rates from SIDS following the 'Back to sleep' campaign in the 1990s, death rates have remained stubbornly high, at around one death in every 2000 apparently healthy infants."

Despite this, little is known about how or why SIDS happens and autopsies of babies who have died from the condition have not given scientists and doctors many clues about the cause of death.

The majority of known risk factors for SIDS - such as parents smoking, heavy blankets and babies sleeping on their stomachs - lead to low levels of oxygen. By providing a direct link between this low oxygen and heart changes in babies at risk of sudden death, the research re-emphasises the importance of avoiding these risk factors. The scientists say that their model will also allow more experiments into SIDS, which may lead to the discovery of further things parents can do to protect their babies.

Heart development in mammals does not stop at birth - instead it finishes at adolescence. One of the important drivers of heart maturation in the hours and days following birth is thought to be the huge increase in oxygen available to the heart muscle following birth, compared with that available in the womb. The scientists carried out their study by manipulating the genes in the 'oxygen sensing system' of the mice - a system that is found in all mammals. This gene manipulation meant that, although the mice were born into the normal atmosphere, the cells in their hearts continued to function as if they were in low-oxygen conditions.

The researchers used ECGs, or recordings of the electrical activity of the heart, to study the effect of this gene manipulation on mice. They discovered the same heart abnormalities that are known to be associated with human infants at risk of SIDS.

"We believe that our work will allow insight into the mechanism of SIDS - how and why babies die - and will allow further work on preventative treatments," said Dr Breckenridge.

He added: "We propose that the risk factors, such as cigarette smoke and babies sleeping on their stomachs, which are known to lead to low oxygen, have a direct effect on the function of the heart muscle, making death more likely. Our work also suggests that screening infants for ECG abnormalities may identify at-risk individuals."

The paper, Hypoxia, Long QT interval and Sudden Infant Death Syndrome (SIDS), by Ross Brekenridge, Melanie Neary and Tim Mohun, is published in Disease Models and Mechanisms.

  • Scientists have developed a mouse model of SIDS (cot death) and linked low oxygen with heart changes and death, reinforcing current prevention guidelines.
  • SIDS is a leading cause of death among babies in the first year of life, causing one death in every 2,000 apparently healthy infants. There has been no reduction in the death rate since the 'Back to sleep' campaign in the 1990s, where parents were recommended to sleep babies on their backs.
  • The mouse model will allow further study of the condition and hopefully lead to new ways to prevent it.