rh factor defined in 1951 yearrh factor - rh factor (rhesus factor);
rh factor - Substance (an antigen; there are actually several, closely related) occurring in blood corpuscles of a high proportion of human beings (85 per cent in Great Britain and U.S.A.). Depends on a complex of linked genes. The rest of the population is without the factor (Rh-negative). Rh-negative individuals do not normally possess antibodies against the antigen they have not got (as they do in the classical blood-groups). But they can acquire such antibodies, as by blood transfusion; or in the case of a woman by bearing Rh-positive children, whose antigen crosses the placenta. The antibody thus formed in a Rh-negative mother may cross the placenta again and if in sufficient concentration, which usually requires at least one preceding pregnancy with Rh-positive child, it may damage a Rh-positive foetus.
near rh factor in Knolik
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