Tuesday, February 12

Inbreeding - some more thoughts

The first time I heard about this was in Saudi Arabia, when a colleague's wife, who is a midwife talked about it. My colleague works in an international bank and has worked in many countries around the world and his wife, being a midwife, also worked. So when she said that 4 out of 10 babies born in Saudi Arabia are genetically challenged, I fell out of bed.

Then I was reminded of this again when the furore over this Pakistani origin Brits broke out in the UK. I quote:

Mrs Cryer raised the issue two years ago after research showed that British Pakistanis were 13 times more likely to have children with disorders than the general population.
Speaking on the Radio 4 Today programme, Mrs Cryer said: "The vast majority of marriages in the Muslim community in Bradford, 80 per cent, are trans-continental. The vast majority of those are to cousins. Many of those do result in either infant mortality or in recessive disorders."
Asked if the problem was recognised in the British Pakistani community, she said: "They are in denial at the moment. But I am hoping that now we have broken the silence leaders will start to have a debate about it and perhaps even give advice and say: 'Look, you can carry on marrying your cousins but there is a price to pay.'
"The price to pay is often in either babies being born dead, babies being born very early and babies being born with very severe genetically-transmitted disorders. This is a blight on that community but particularly on specific families." In one family she knew, all three daughters had to have liver transplants. "One girl has had, I think, four liver transplants to the point where she's so worn down by all of this the poor girl is having to receive psychiatric help as well. No one wants to wish that sort of thing on their children."

I then went and looked for the references and found it in an abstract.

First-cousin marriage may be a significant risk factor for specific types of congenital heart disease in a consanguineous population. Inbreeding studies suggest an autosomal recessive component in the cause of some congenital heart defects. We studied a large sample of patients with structural congenital heart defects (CHD) identified through the Congenital Heart Disease Registry at King Faisal Specialist Hospital in Riyadh, Saudi Arabia. After exclusions of chromosome abnormalities and non-participation, data were collected on 891 consecutive patients who were registered between January and August, 1998. Data on first- cousin consanguinity and type of CHD diagnosis were collected. A z test of proportions was used to determine the association between consanguinity and subtypes of CHD. Data indicate that the proportion of first cousins in the CHD sample is higher than the proportion in the general population, supporting a hypothesis of autosomal recessive gene involvement in congenital heart disease. When subgroups of CHD were analyzed, first-cousin consanguinity was significantly associated with ventricular septal defect (VSD), atrial septal defect (ASD), atrioventricular septal defect (AVSD), pulmonary stenosis (PS), and pulmonary atresia (PA). There was no relationship between consanguinity and tetralogy of Fallot (TOF), tricuspid atresia (TA), aortic stenosis (AS), co-arctation of the aorta (CoA), and patent ductus arteriosus (PDA). Thus, in a population with a high degree of inbreeding, consanguinity may exacerbate underlying genetic risk factors, particularly in the offspring of first cousins. There may be a recessive component in the causation of some cardiac defects.

My gut feel is that its cultural and the fact that women are in purdah. So the families only get together and external people dont. So when you are having cousins spending time together, its but natural to have cousin marriages. Complicated, not sure if I know the full answer but this surely is avoidable given the advances in genetic engineering?

All this to be taken with a grain of piquant salt!!!

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