Rh negative

Rh negative blood type, also known as Rh(-), refers to the absence of the Rhesus factor, a protein substance present on the surface of red blood cells. This characteristic is significant in the field of blood transfusion and pregnancy, where the compatibility of Rh factors between the donor and recipient, or mother and fetus, is crucial.

Overview

The Rhesus factor, discovered in 1937, is a genetic trait that determines the presence or absence of specific antigens on the surface of red blood cells. These antigens are proteins that can trigger an immune response if they are foreign to the body. The term "Rh" comes from the Rhesus monkeys in which the antigen was first discovered. Individuals who have the Rh antigen are classified as Rh positive (Rh+), while those without the antigen are Rh negative (Rh-).

Genetics of Rh Negative

The Rh factor is determined by a pair of genes, one inherited from each parent. The Rh positive allele is dominant over the Rh negative allele. Therefore, a person will be Rh negative only if they inherit the Rh negative allele from both parents. This genetic trait is less common globally, with the prevalence of Rh negative individuals varying significantly among different populations.

Health Implications

Blood Transfusion

In the context of blood transfusion, the Rh factor plays a critical role in ensuring compatibility between the donor's and recipient's blood. An Rh negative individual can safely receive blood only from another Rh negative donor. However, Rh positive individuals can receive blood from both Rh positive and Rh negative donors. Transfusing Rh positive blood into an Rh negative recipient can lead to an immune response, potentially causing hemolytic transfusion reactions.

Pregnancy

During pregnancy, the Rh factor can lead to complications if an Rh negative mother carries an Rh positive fetus, a condition known as Rh incompatibility. The mother's immune system may recognize the fetus's Rh positive red blood cells as foreign, producing antibodies against them. This can lead to hemolytic disease of the newborn (HDN), where the baby's red blood cells are destroyed by the mother's antibodies. To prevent this, Rh negative pregnant women are given an injection of Rh immunoglobulin (RhIg), which helps prevent the development of antibodies against Rh positive blood cells.

Prevalence

The distribution of Rh negative blood varies widely across different populations and regions. It is most commonly found in individuals of European descent, with the highest prevalence in the Basque people of Spain and France. In contrast, Rh negative blood is much less common in African and Asian populations.

Conclusion

Understanding the Rh factor is essential in the fields of medicine and genetics, particularly in managing blood transfusions and pregnancies. While being Rh negative poses certain health considerations, advancements in medical practice, such as the use of Rh immunoglobulin, have significantly mitigated these risks.