High likelihood that my daughter does not have an autosomal dominant condition

By Razib Khan | March 7, 2013 7:21 pm

After my previous post my wife started doing research online. The autosomal dominant condition that I have is almost certainly localized to one particular chromosome (there is a large effect QTL there that is strongly associated with my condition). Additionally, I inherit this condition from my mother. My daughter has her whole pedigree genotyped, thanks to 23andMe. My wife went into the Family Inheritance feature, and compared the identity by descent blocks shared between my mother and my daughter. And, it turns out that on that chromosome the only segments inherited from me, her father, come from my father. Ergo, she can not have inherited the autosomal dominant condition from my mother, since she did not inherit those alleles from her!

We are very happy right now. This is one reason I don’t really care about what the F.D.A. thinks about direct-to-consumer personal genomics. We’re talking about commodity technology. And no one is going to stand between you and your health, if you are motivated.

Addendum: With hindsight I could have figured this out myself a year ago. It just hadn’t crossed my mind.

CATEGORIZED UNDER: Personal Genomics
  • http://twitter.com/zenndiagram Zenn Diagram

    Congratulations on the good news. It is nice to see that you are able to benefit from the skills that you use at work.

  • http://twitter.com/fallmists Jessica C

    Razib, your wife just thoroughly schooled you. ;) That’s awesome news.

  • http://twitter.com/jxchong Jessica Chong

    Now that was simple!

  • Sandgroper


  • Dmitry Pruss

    Neat, one may need to incorporate it into all clinical tests for genetic predisposition whenever there is clearly a single locus (or maybe a couple loci) resposible. Alas, usually the patients are concerned about conditions which aren’t extremely rare and specific (and thus a relative who doesn’t share the haplotype may simply be a phenocopy), or about conditions with far too many loci implicated (and thus someone’s granny will be sharing at least one of the relevant loci anyway).

    Razib BTW have you seen / do you want to put a more detailed comment on Jerome Kagan’s recent interview about genes, nurture, and intelligence, and the study cited there? He said,
    The heritability is 50 percent if your parents went to college. But if your parents never graduated high school the heritability is zero. Zero. Eric Turkheimer has proved that [in his 2003 study on how socioeconomic status modifies heritability of IQ in young children.]

    Genes do make a contribution to the IQ score — but a flower needs soil. The environment for poor people is so overwhelmingly powerful, it washes out the genetic effect. There is a genetic contribution to IQ, but you can’t detect it when you’re living in a deprived environment.

    • razibkhan

      the turkheimer study gets cited a lot. i’m inclined to believe it because it is plausible, and makes sense in a quant gen framework. but it would be nice if more people did research and reproduced this finding.

      • Dmitry Pruss

        It may be cited a lot, but perhaps out of context? The 2003 paper clearly says that their goal is study determinants of intelligence of children; in fact the children were tested at the age of 7 using WISC (which measures vocabulary richness, reading comprehension, and general knowledge). Wouldn’t the nature of the test, and the age at testing, tend to over-accentuate the environmental effects? How good is correlation between WISC @ 7 and adult intelligence?

        As I mentioned to you great many times, there is little doubt that intellectually nourishing environment of children provides for more fun / more meaningful parent-child and teacher-child interactions a few years later. But most adults believe that the nurture effect must be lasting a lot longer, perhaps lasting for the lifetime; and that’s where they keep citing, alas, the Turkheimer study which proved nothing of the sort.

      • Jason Malloy

        I’ll just repeat my
        from two years ago:

        “That same Turkheimer paper gets referenced over and over again, because
        it reported the “wanted” conclusion and it was widely referenced in the
        media. In the academic literature Google Scholar gives it 385 citations.

        For comparison, a similar paper
        came out about the same time using another good data set (Hawaiian
        Family Study of Cognition). It did not find the GxE, and so not one
        media outlet talked about. Google Scholar says it only has 8 citations.

        See also.

        • Dmitry Pruss

          Thanks, Jason! The 2008 paper raises some important issues about Turkheimer’s study, which already bothered me even before I read it. For one thing, there must be significant correlation between socio-econ status and genetics in their cohort (which has a minority-majority fort of ethnic makeup); then, big-city living and the stress of rising twins make have unique, specific effect on health and upbringing of children (which Turkheimer et al. partly admitted in that they tried to explain away, and censor, the outliers).

          But most peculiarly,van der Sluis et al., just like myself, are surprised by the direction of “Turkheimer effect” which is usually described as “inhibitory effect of poorly nurturing environments, which overrides inherited changes”. What the 2003 study seems to have observed is something quantitatively different, and surprising. They see higher variability / reduced correlation of test results in both fraternal and id twins from poor SES households. It’s like these kids are less similar to their parents; no, they are less similar to their own twins (identical and non-id alike). My hunch is to dismiss it as a fluke. But if you take this observation at its face value, then it appears to contradict their model’s prediction that “poor shared environment makes everyone dumb, overriding genetics”. No, in their study, poor nurturing environment, counterintuitively, made twins more varied in intelligence … rather than more similar.

  • svman

    Can you explain this in more detail? Did you have to get 23andme gene sequences for your parents and wife also for the analysis? Are there online tools to assist the reasoning?


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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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