Inbreeding in the Persian Gulf

By Razib Khan | August 25, 2010 5:01 pm

On the heels of my post on cousin marriage, I thought readers might find this article on genetic screening in the United Arab Emirates of interest. One way to tackle the problem of genetic diseases which emerge out of consanguineous unions apparently isn’t to discourage the unions themselves, but dodge the outcomes. So pre-implantation screening of eggs as well as selective abortion of fetuses both seem to be options being evaluated. Aside from the costs, especially in the former case (though abortions are not without risk, and the initial stages of pregnancy are an investment of time as well), I still think there are long term problems with this. But first, Alan Bittles (who produced the map in the previous post) points to a major shortfall of a simple do-not-marry-cousins heuristic in this case:

People from the same tribe can also be highly genetically similar, he said.

“You can’t just compare the health of those children born of cousins but the comparison must be made within the tribes as well as between them, as some disorders are unique to particular tribes,” he said. “To stop consanguinity affecting health, you’d not only need to stop first cousin marriage but people in the same clan too, which is highly improbable and going against centuries of tradition.”

Another medical specialist opines:

Dr Anand Saggar, a clinical geneticist based in London, sees patients from the Gulf — who have been sponsored by their governments — at his clinic in Harley Street.

Western prejudice and health economics have led to the negative attitude towards cousin marriages, which are legal and accepted in many parts of the world, he said, pointing to Amish communities in the US.

“We’ll never get rid of any old genetic diseases because our genetic code keeps on mutating. You just have to accept that genetic disease is part of our evolution. It is a foolish and erroneous assumption that to stop marrying cousins would eradicate genetic disease.”

The National is paper based out of the United Arab Emirates, a former British colony. Therefore, I won’t put it past them to quote mine or distort (rule: beware of British newspapers!)…but this is just kind of a dumb assertion. The problem with inbreeding isn’t that one has deleterious alleles, it’s that there are correlations of deleterious alleles at the same locus. So the Jewish community has sharply reduced the manifestation of Tay-Sachs disease through genetic screening. The Amish community is is also impacted by recessive genetic diseases. As I noted earlier, inbred communities should have lower aggregate genetic load, and yet the the fact that deleterious alleles are concentrated on specific loci mean that they have reduced physiological fitness.

I’m skeptical of Alan Bittles assumption that there’s something set in stone about current Arab practices. Apparently miniskirts and exposed hair were de rigueur among the Arab female smart set in the 1960s, but now veiling is all the rage. Times change. But, the logical conclusion of generations of genetic screening of particular Arab lineages is that the clans of the Persian Gulf will eventually transform themselves into clones with very low mutational load. Even if the power of screening shields these lineages from the ill effects of inbreeding (by literally yanking out all the deleterious alleles from the gene pool by discarding eggs with problematic genotypes every generation), biological uniformity is going to have problematic long term consequences when it comes to battling co-evolving pathogens. Monocultures aren’t built to last.

In any case, interesting idea for a science fiction short story. The formula would be to take a pre-modern custom (e.g., cousin marriage) and mix it with future technology, and iterate forward.

CATEGORIZED UNDER: Culture, Genetics
MORE ABOUT: Culture, Inbreeding
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  • dan

    freakin’ gold. more, please. on a side note today i saw a (pure bred) dog with a lower jaw that protruded at least 1/2 inch past his upper jaw. sad….

  • Åse

    I’m kind of struck/fascinated by the Rube Goldbergish way of solving a problem. No no no, we won’t change our ways. Here’s a complicated, risky, costly other way of possibly fixing the problem. Yeah, let’s do it that way.

    Just thinking about the psychology of it, and not quite sure what to make of it (yet). I’m sure culture changes (as the incentives changes), but that is a separate questions. Why would people even suggest such a thing, rather than the other.

    (Made me also think about the japanese and their robot thing, and a girl who wrote in to an advise columnist and asked how she would go about getting a hysterectomy, because she resented having to pay for tampons every month – yes that was in sweden).

  • http://www.latif.blogspot.com Zachary Latif

    Fascinating story about the hysterectomy.

    http://gulfnews.com/news/gulf/uae/society/rise-in-number-of-spinsters-as-emiratis-marry-foreigners-1.672200

    Not directly related to your post but here are the new restrictions:

    A proposal in regard to the laws that regulate the marriage of Emirati men to foreign women has been prepared, although it has not yet been approved. The law will include obtaining a special permission to marry from the Ministry of Interiors. Permission will only be granted if the marriage meets criteria such as:
    1. The wife must be Arab and Muslim.
    2. The husband must not be married to any other woman at the time.
    3. The age difference should not exceed 25 years.
    4. The husband must be financially capable of supporting the woman.
    5. The couple must be free of any hereditary or sexually transmitted diseases.
    6. The wife must not be banned from entering the country for any reason.

  • Jolanta Benal

    I notice another respondent has already pointed out the correlations with dog breeding. The kennel club types insist that they can “improve” dogs by not breeding those with genetic defects, but of course they’re still increasing genetic uniformity within the breed because the gene pool’s closed. And the dogs get sicker and sicker.

  • Nondescript American

    I’m kind of reacting against using “inbreeding” for a title about human behavior. Technically it’s perfectly true, of course, but the literature seems to lean on “consanguinity” more.

    That being said, I am very happy to see you note the point by Bittles about marriage in the clan as well as cousin marriage — or about population subdivision. Many of those in Pakistani biradari are actually not known to be have any degree of cousinship, although it is presumed that they are somehow related. The genetic variation in these groups gets reduced due to not marrying out for long periods of time, so even if you ban first-cousin or even any known cousin marriage there will still be increased frequency of ailments. For their part, the Amish ban anything closer than second-cousin marriage and continue to have problems.

    I’m very skeptical of any kind of long-term prediction that cousin marriage will lead to inbreeding depression in Arab societies. Why? Well…it hasn’t. We’ve had quite a long time to test the hypothesis! Historically cousin marriage has only been one of many options. I don’t see screening changing this, because I don’t really see cousin marriage being that much more frequent as a result. People are already not taking into account the genetic aspect. I agree with Steve Pinker that its long-term biological disadvantages have basically been “small.” (And looking that long term, I’d be much more concerned anyway about the effects of more direct transhumanist meddling.)

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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