Genetic variances may provide clues to risk of disease

Genetics: Tiny differences in your genetic make-up can tip the balance and trigger diseases. These very small variations are now being catalogued with a view to better diagnostics but also the possibility of new treatments.

The BA Festival of Science yesterday heard a discussion on how common genetic variants could affect disease risks. "Why is that so? Quite frankly we don't know," said Trinity College professor of biochemistry Prof John Scott.

The possibility of searching for the minor changes in our genetic blueprint that can prompt disease only arose with the publication of the entire human genome, the three billion step DNA code held in every cell in the body.

The idea is to detail small changes that can confer higher or lesser risk of disease. "We are looking at very, very common genetic variants," Prof Scott said. His laboratory is credited with finding two causative genes for spina bifida, a neural tube defect.

GPs typically ask new patients a battery of questions about their own and their immediate family's health as a way to assess disease risks. The hope is that cataloguing gene variants will in time deliver a similar result, with a quick genetic profile indicating a risk for a given disease.

Prof Scott's US National Institutes of Health-funded research is looking at variants associated with spina bifida. "It is known to have a very big genetic element," he said. Yet the disease risk falls dramatically when a prospective mother takes folic acid supplements as a way to block neural tube defects in the foetus.

The two genes found by Prof Scott are associated with how the body handles folic acid. Each has a very small effect but this is sufficient to increase spina bifida risk.