Blood simple

One of the few unalloyed positives of my up-and-coming surgery is that i have had to be “blood typed”. That is, the nurse extracts a load of blood from my arm (no mean feat, given my exceeding and irrational fear of needles) and, along with other tests, they check up what blood type i am.

Which turns out to be B positive.

I like that. As i then tweeted: B positive – blood type and personal credo!

I also like that it turns out to be relatively rare (just 7-8% of the population have it) – though that raises a minor moral dilemma, since the NHS site also tells me that they desperately need B Positive donors.

So i mention this to andrea, who promptly checks her records and – well i never! she b b positive soon.

As is my daughter, Natasha.

Now what are the chances of that?

Intriguing. Purely at random, the chances of two adults coming together with that blood type are around 0.6% or 3 in 500. That assumes, of course, that blood type is not associated with some other genetic components leading to non-random association.

And to have a daughter with the same type? Hmmm. Not sure about how blood type is transmitted. I guess it is parental, in which case, there is a 50/50 chance of Natasha having the same type as me… and so the chances of THREE of us having that blood type dwindle to around 3 in a thousand.


Also cool that if any one of us has a major accident…we have two possible blood donors instantly to hand.




7 Responses so far »

  1. 2

    Sabine said,

    Let’s see – rhesus factor + is single gene and dominant, so if either parent is +, so will the children be.

    AB0-type is a little more complicated. There’s two genes involved, both of which can carry each type. If you exhibit type B we say B is your phenotype. There are two possible combination of genes (genotypes) that will lead to phenotype B: BB and B0.

    So both you and Andrea have either of these, leaving us with three distinct possibilities: a) both are of genotype BB, b) both are B0 or c) one is BB and one is B0.
    a) there’s just B in the mix so any common child of you will have genotype BB and phenotype B
    b) your children’s phenotype can be either B or 0. 0 will only we shown when both genes are 0 so there’s a 75% chance of phenotype B and 25% of 0. (statistical genotype distribution is: 25% BB, 50% B0, 25% 00)
    c) one of you will give a B gene in any case so the child will show phenotype B with a 50% chance of either genotype BB or B0.

    Honestly – what do they teach in school over there? These are the simplest form of Mendelian genetics and the textbook case in school.

    As to donating blood – do it as soon as you can, there’s people needing it and it’s a very relaxing experience. In fact I call my quarterly blood donation my wellness holiday because you get pampered for once.

  2. 3

    SophieH said,

    Hmmmm, bit of a hot potato this blood donor issue. Personally, as I don’t really have a problem with needles (I have blood tests at least every three months) and see to as a terribly worth while thing to do. I would very much like to give blood but am specifically excluded even though I am probably better versed in sexual health than the average person and aware of my HIV, Hep B and C than almost anyone else I know. Although I’m not going to list the reasons why I’m excluded here you can probably use your imaginations to deduce the main criterion.
    Now I’m not saying that I’m immune to any of the blood born illnesses which the transfusion service is trying to screen but do find it a bit weird when, as someone who has always considered herself to be psychologically female so therefore has always found men attractive and chosen to act on this. So unlike a born woman this emphatically excludes me. Another strange anomaly seems to be the exclusion of people like me even if I have strictly followed all the recommendations for safe sex. Very discriminatory I think. And all this because of the awful happenings of the early 80’s when there was a shortage of donated blood forcing the the heath service to BUY in blood which had been sold, not donated, in the US leaving us with he legacy of people infected here. Surely the health service knew that blood in the US is bought from any old donor, in many cases to fund drug habits and from others at the, shall we say, more desperate end of the socio-economic scale.
    I do wonder how I will stand later in the year if I’m successful in gaining my GRC?

    • 4

      Sabine said,

      The screening based on sexual preference is bollocks.

      Sexual orientation does not say anything about promiscuity and risk of catching a disease by brainlessly screwing anything that holds still for long enough. The official position of the German Red Cross is still that homosexuals are more likely to be infected based on the 80’s view of gays as randomly having sex with anyone willing in a railway station bathroom.

      I don’t know the official position on trans but I suppose it is similar.


      • 5

        SophieH said,

        I agree, succinct and to the point. I suppose you could say blood isn’t so simple, in fact anything but to some of us…

  3. 6

    Liz Church said,

    My endo told me not to donate blood because of the hormones circulating in my system.

  4. 7

    Lois said,

    I was told that I should not give blood as I have had surgery requiring blood transfusions after 1980!!!!

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