A British politician has said that marriages between first cousins should be outlawed because of the increased risk of genetic disorders in their children. Ann Cryer, the MP for Keighley, Bradford, told the BBC's Newsnight programme that British Asians should be persuaded to abandon the tradition. A report commissioned by Ms Cryer showed that babies born to British Pakistani couples make up just 3.4 per cent of all births, but account for 30 per cent of all children affected by recessive genetic conditions.
Ms Cryer described the risk of genetic disorders in children of first cousin marriages as 'a public health issue', like smoking, drinking and obesity. 'I think the same should be applied to this problem in the Asian community', she told the BBC, adding 'they must adopt a different lifestyle. They must look outside the family for husbands and wives for their young people'. In Bradford, it is estimated that more than three quarters of all British Pakistani marriages are between first cousins.
Consanguineous marriages are common in many cultures, where they are viewed as having many social benefits. Such couples may seek genetic counselling, since they are at increased risk of having a child affected by a recessive disorder - conditions that affect people who inherit two copies of a particular mutated gene, one from each parent. Although it is thought that everyone carries several recessive disease genes, most do not affect a person's health, because their effects are masked by a normal copy.
The more closely related two people are, the more likely they are to carry copies of the same mutated gene. Unrelated parents have around a two per cent risk of having a child with a severe genetic condition, while in first cousins this risk rises to five per cent. So on average, 95 per cent of the children of first cousins will be healthy, although the risk of a recessive disorder increases if there is a family tradition of such marriages. In addition, certain disorders are more common in some populations - for example cystic fibrosis in people of white European origin and thalassaemia in people of Asian and Mediterranean descent.