Counseling in medical genetics / Sheldon C. Reed.

  • Sheldon Clark Reed
Date:
1963
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Counseling in medical genetics / Sheldon C. Reed. Source: Wellcome Collection.

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    Blood Genetics J 39 incompatible zygotes. Such studies indicate that there is an im¬ portant loss of the A and В alleles during the fetal and postnatal development. Therefore, in order to maintain the frequency of A and В genes in the population, they must be selected for later on in life. If their selective advantage is related to infections rampant in the past but no longer of importance, we could expect the frequency of A and В to decrease in the future. This is, of course, pure speculation—but good fun! The M-N system of blood groups is sharply different from the A-B-O system in that no one has antibodies against either the M or N antigen and cannot produce them even upon repeated transfusions. Rabbits will produce distinct antibodies against the M and N antigens after a series of injections, and the rabbit antibodies can agglutinate human blood. To distinguish between the genes for M and N antigens in man we are forced to resort to laboratory animals. Except for its usefulness in clari- fying paternity disputes and zygosity in twins, the M-N system is mainly of academic interest. Such is far from the case with the Rhesus factors. In the flush of excitement over the 1940 discovery of this group, the problem of the erythroblastotic baby has probably been some¬ what overemphasized. However, to the couple meeting the situa¬ tion in their own child, there is no lack of seriousness or im¬ portance in it. While to some, almost always males, a wasted pregnancy seems to be a minor inconvenience, this view is not shared by the woman who has suffered the experience. To the women who have had erythroblastotic babies, and there are thousands of them, the new understanding of the Rhesus factors comes from one of the brightest pages of science. These women are indebted to many scientists, among whom the names of Landsteiner, Levine and Wiener must not be forgotten. Landsteiner and Wiener (1940) immunized rabbits and guinea pigs with the blood of Rhesus monkeys and made the sur-