Heated controversy over cousin marriages in Britain.
The Guardian argues it's fine, legal in the UK for centuries, done by Darwin, HG Wells and Queen Victoria; and a 2002 study (
prev) found little increased risk. But in Bradford, England, where
half of babies born are to ethnically Pakistani parents, cousin marriage is very common -- as high as 70% in that community. Bradford, with 1% of British population, has
70 youths with terminal disorders which lead to dementia-type illnesses – eight per cent of the UK total. Should the government ban cousin marriage? Encourage genetic testing? Or keep its mouth shut?
The fact that consanguineous marriages are most common among Muslim Pakistani immigrants makes the discussion more contentious. The Environment Minister Woolas
was rebuked in February for expressing concerns
intemperately.
According to
a 2005 BBC investigation, British Pakistanis account for 3.4% of all births but have 30% of all British children with recessive disorders, and the Birmingham Primary Care Trust estimates that one in ten of all children born to first cousin marriages in Birmingham's large Pakistani community either dies in infancy or goes on to suffer serious disability as a result of recessive genetic disorders.
The 2002 study may have underestimated risk by ignoring the compounding effect -- i.e. the risk for two cousins whose family hasn't previously mixed may be very different from that in an extended family (e.g. the Windsors) who mix repeatedly for generations. And professor Alan Bittles, a leading expert, notes that
within some communities even non-cousin marriages carry higher risks of these rare genetic disorders because those involved are from the same "biraderi" or clan.
Better data is on the way from
the Born in Bradford study (
wiki), now a year old. It's
the largest children's health study in the world, aiming to track all babies born in the city from autumn 2006 to early 2008 (approx. 10,000 children) until age 16. They have found 150 different genetic disorders among those children, where 20-30 would be expected in a comparable city.
posted by delmoi at 7:17 PM on May 23, 2008 [1 favorite]