Risk of birth defect doubles for cousin couples -study
By Kate Kelland
LONDON (Reuters) - Children whose parents are cousins run more than double the risk of being born with a congenital abnormality, although the overall rate of such birth defects remains low, according to new research findings.
A large study in a British city with a large Pakistani community, where marriage between blood relatives is fairly common, found that so-called consanguineous parents accounted for more than 30 percent of birth defects in babies of Pakistani origin.
Researchers said the findings were important evidence for use in educating populations that accept and sanction cousin marriages - including Amish, Kurdish, Romany and other relatively closed communities - about the potential risks for children's health.
Birth defects, also known as congenital abnormalities, can range from relatively minor problems such as extra fingers or toes through to more life-threatening problems such as holes in the heart or brain development disorders.
Experts estimate more than a billion people worldwide live in communities where blood-relative marriage is a cultural norm.
"Whilst consanguineous marriage increases the risk of birth defect from 3 percent to 6 percent, the absolute risk is still small," said Eamonn Sheridan, a senior lecturer in clinical genetics at the University of Leeds who co-led the study and presented its results at a briefing in London.
He added that this still means 96 percent of blood-relative couples are likely to have babies with no birth defects: "It's important to note that the vast majority of babies born to couples who are blood relatives are absolutely fine."