Piecing together the cot death puzzle

A University of Dundee-led team of Scottish researchers have found what they believe could be a key piece of the puzzle in discovering why some infants are more susceptible to serious illnesses and cot death.

Professors Ann Burchell and Robert Hume, in the Division of Maternal and Child Health Sciences, together with colleagues from the University of Edinburgh and the Royal Hospital for Sick Children in Glasgow, have identified defects in glucose production, particularly in premature and small babies, which make infants more susceptible to a variety of risk factors linked to cot death.

"Figuring out why some babies and not others are more susceptible to sudden infant death syndrome or other serious illnesses is like putting together a massive jigsaw puzzle," said Professor Burchell. "What we have found is one piece of that puzzle, which we hope will lead us to discovering larger pieces."

Low birth-weight infants are particularly vulnerable to low blood glucose levels and low birth-weight is also a risk factor for sudden and unexpected death in infancy. It has previously been shown that some infants dying suddenly and unexpectedly have defects in liver glucose production, which could lead to low blood glucose at times of stress or reduced milk intake.

The research has been funded by the Scottish Cot Death Trust. Dr John McClure, Chairman of the Trust, said, "Over many years, Professor Ann Burchell and her colleagues at Dundee have carried out invaluable work towards finding an expanation for cot death."

"The findings in this research are a useful addition to our knowledge and as Professor Burchell puts it so clearly, it is a piece in the puzzle which will help us to explain the cause of this devastating event. The Scottish Cot Death Trust is proud to be funding such valuable research."

The Dundee research team concentrated on molecular defects in liver genes involved in glucose production and also problems in the regulation of these genes. They found that in some babies some key genes which make and transport glucose around the body were not `switched on' soon enough after birth.

"This part of our work has concentrated on a system called hepatic glucose-6-phosphatase, which we all have," said Professor Hume. "Unfortunately in some babies this system does not work correctly in that it doesn't start working soon enough after they are born."

"This delay causes low blood glucose levels (hypoglycaemic episodes) in the baby and places it at risk."

The researchers stress that this finding alone does not explain cot death, and that many other genetic faults and environmental factors may be associated, perhaps in combinations, with the syndrome.

"We must stress that we are not saying this is the cause of cot death. It is one risk factor among many which appears to make some children more susceptible to cot death and exaggerated responses to illness," said Professor Burchell.

"We already know quite a lot about a number of risk factors surrounding cot death, including bedding materials, smoking in the home, and so on. The work we are doing is concentrating on the abnormal genetic and hormonal regulation that makes some babies at increased risk of these factors."

"Much more work still needs to be done, both in terms of examining a much wider range of samples of all infant deaths and in testing both healthy babies and those who fall ill to allow us to determine all the factors which lead to cot death."

"Our ultimate aim in this strand of work we have carried out is to gain sufficient knowledge to be able to determine, prior to discharge home, which infants are at greatest risk of low blood glucose at times of stress. Once these infants are identified as being at risk then it would be possible for us to apply preventative measures."

The research is published in the Journal of Pathology.