Genetic link to sleeping disorder

A gene variation that is known to be linked to Alzheimer's disease and cardiovascular problems has also now been linked to sleep apnoea, a condition in which sufferers snore and have lapses in breathing while they sleep. Breathing lapses can occur when the muscles in the mouth and throat relax too much, causing the tongue to partially block the airway.

Sleep apnoea is thought to have some hereditary basis, as it seems to run in families. It has been estimated that as many as 18 million Americans have sleep apnoea. But a new study, published in the Journal of the American Medical Association last week, shows that eight per cent of cases could be due to a genetic variation called apolipoprotein E-4.

A group of 791 adults were studied by the team led by Dr Hiroshi Kadotani of Stanford University. Twelve per cent of the 222 participants in the study who had the E-4 variation had either moderate or severe sleep apnoea, compared to only seven per cent in those without the variation. The researchers noted that sleep apnoea may be linked with the E-4 trait which impairs cognition as apnoea may deprive the brain of oxygen for long enough for it to be irreversibly damaged. But they stress that the research does not necessarily imply that all sufferers of sleep apnoea have an increased chance of developing Alzheimer's or cardiovascular problems.