Genetic faults are linked to some vitamin deficiencies

AS MANY as one in 10 Irish people may have a genetic fault that could leave them deficient in certain vitamins, according to an Irish research group. The discovery has important implications for controlling disorders such as spina bifida.

It may also force a rethink in what represents a "normal" daily vitamin allowance, said Prof John Scott, head of the Department of Biochemistry at Trinity College, Dublin, in a recent edition of the medical journal, the Lancet

"This is a first," he said yesterday. Drug research had shown there were significant differences in the way people responded to drugs, but this had not been shown to be true for nutrients such as vitamins. The work goes further, however, by identifying two identical genes responsible for handling the vitamin, folic acid (folate).

As many as one in 10 people here have a fault in both genes which means they cannot make full use of the folate in their diets. Having adequate folate levels is vital for a woman planning a pregnancy. Low levels of this vitamin are associated with disabling and sometimes fatal problems in foetal development, called neural tube defects, which lead to spina bifida and other disorders.

People with the two faulty genes "have a 20 per cent or more deficiency in their folic acid status. The deficiency is critical in the case of spina bifida," Prof Scott said.

His group studied folate levels in pregnant and non-pregnant women, and found that women in either group who had two faulty genes also had significantly lower folate levels compared to those who had normal genes.

Their findings bring into doubt assumptions made about the amount of vitamins needed to maintain a healthy diet. "They don't take into account those who are not normal. This shows that the definitions will have to be revised," Prof Scott said.

Ireland has a comparatively high incidence of neural tube defects with about 200 cases a year. About half of these children survive. Trinity researchers have studied these disorders since the 1970s and have shown that the risk of spina bifida can be reduced by 75 per cent by maintaining good folate levels. This is critical during the four weeks following conception when the foetus's neural tube closes to form the spinal column.

Too few women are taking folate before pregnancy. "The compliance for spina bifida has been disastrous," Prof Scott said. About half of all pregnancies are unplanned, he said, and only a small fraction of those with planned pregnancies bothered to take the vitamin supplement.

"Informing people just doesn't work," he said. A similar situation persists in the US, but authorities there introduced legislation in January this year requiring all flour sold in shops or to bakeries to include a folate supplement. The Government is considering similar regulations, he added.