How fast is your biological clock ticking? We’ll know soon

My family breeds about as fast as sequoias.  A cousin had a child at 46 who is presently burning up Columbia.  My brother had a child at 48, also doing OK.  But we do know that the older the parents, the more likely a kid is to have genetic problems (Sarah Palin & Trig).  So what are the odds and how do they change with age?

We don’t really know, but in the next five to ten years, we’ll have a good idea.  The first human genome project sequenced most of the 3,200,000,000 positions in our DNA. It cost billions and took years.  DNA sequencing technology marches on at an incredible pace.   A recent paper rated only 4 pages [ Science vol. 328 pp. 636 – 639 ’10 ].  The complete genome sequence of 2 parents and 2 of their children was performed (to 1/100,000 accuracy yet).  There was known genetic disease in the family and the authors were looking for its cause.  The genome sequences of the parents and their children were compared position by position (using computers of course). If the base (adenine, thymine, guanosine, cytosine) at a given position differed from that of the parent supplying the surrounding DNA, a mutation had taken place between the generations.  Since they had looked at the entire genome, they could count the number of mutations they found.  The rate of mutation was 1.1 per 100 million positions, making about 30 new mutations between generations.  

So this isn’t by guess and by gosh, but an actual mutation rate and a count.  While medical science marches on,  our biology has not.  We’ll soon be able to give the numbers of the mutations occurring between parents and progeny at a variety of parental ages, when enough of this sort of thing is done. And it definitely will be done as only 10 years separates the incredibly laborious first human genome project from this paper.  

Interestingly, the authors didn’t mention anything about this application in their paper, so this may be (gasp) an original idea.

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  • Matthias W.  On May 23, 2010 at 7:01 pm

    i think it was observed in the Lenski experiment on E. coli that the biological clock doesn’t tick very regularly. I’m not sure if that was only on an evolutionary level (gaining new useful traits) or also in the rate of mutation.

  • luysii  On June 5, 2010 at 8:38 am

    Each human ovary contains 400,000 follcicles, most of them remaining dormant throughout a woman’s life [ Proc. Natl. Acad. Sci. vol. 107 pp. 10280 – 10284 ’10 ]. Each follicle contains an egg, so the problems seen with late reproduction are not due to a deficient supply of eggs.

  • luysii  On November 5, 2010 at 8:35 am

    Just to show how fast things are moving along. Nature vol. 467 pp. 1026 – 1027 ’10 asked 90 genomics centers and labs to estimate the number of sequenced human genomes they’ll have on hand by the end of 2011. The answer — around 30,000. How many will be members of the same family (particularly parents and children) isn’t known, but we’re certain to have lots of them in 10 years (if humanity doesn’t get involved in a nuclear war).


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