The rhesus factor and haemolytic disease

Abstract

The Rh or rhesus factor, so-called because it is found in the blood of rhesus monkeys, is an antigen (that is, a substance capable of stimulating the formation of an antibody) found on the erythrocytes of 85–87% of Europeans who are described as Rh-positive. The antigen is not present in the red blood cells of the remaining 13–15% of the population who are Rh-negative. There is an ethnic variation in the percentages of population whose blood contains the Rh factor, and in many countries of the Far East Rh-negative blood is a rarity. The factor is inherited as a dominant Mendelian characteristic which means that an Rh-positive individual may be either homozygous when the factor is acquired from both parents, or heterozygous, from one parent only (see pages 34 to 36).