Rh factor and its significance by Prabeen

Rh factor is discussed in detail with its significance.
By Prabeen Kumar Mahato

1. Prabeen Kumar Mahato 4 th semester J. K. College, Purulia Rh Factor And Its Significance

2. ABO Blood Group System But in case of Rh system there is no anti-Rh antibody in the plasma of Rh negative person unless this person get blood transfusion from a Rh positive person.

3. What is Rh-factor ? Type → N onglycosylated , Hydrophobic cell surface proteins. Location → Cell membrane of RBC Discovered → by Landsteiner and Wiener in 1940 in the blood of Rhesus monkey. Types of antigens in Rh factor → approximately 49 types of antigens

4. Which antigen determines Positivity of Blood Group ? Primary antigens → C(or c) D(or d) E(or e) antigens, although it actually contains many more. D antigen plays significant role in determining the positivity of the Rh system. Antigenicity order of Rh antigens: D > c > E > C > e

5. Brief account on the Genetics of Rh factor Fig. (A) Genes for Rh antigens at p arm of Chromosome 1; (B) Rh antigens on RBC

6. Percentage of Rh(+) Blood among People 85% of Caucasians are Rh(+). 95% of American blacks are Rh(+). 99% of Asians are Rh(+). 100% of Africans are Rh(+).

7. Rh-positive(D-positive) or Rh-negative(D-negative) determinant The Rh antigens are thought to play a role in maintaining the integrity of the RBC membrane—RBCs which lack Rh antigens have an abnormal shape. Anti-Rh antibody production in Rh-negative blood Rh factor is very much significant in blood transfusion process. Significance of Rh-factor

8. Significance in Blood Transfusion D-negative individuals who have received a transfusion of D-positive blood (even years previously) can have appreciable anti-D antibodies and thus may develop transfusion reactions when transfused again with D-positive blood. And this can lead to death of the recipient. So it is very important to cross check the Rh group of the donor and recipient to avoid transfusion reaction.

9. Significance of Rh in Blood Transfusion Transfusion reaction Need to be cross checked

10. ABO Mismatch Rh Mismatch Immediate transfusion reaction No transfusion reaction in 1 st transfusion Immediate transfusion reaction in 2 nd transfusion Anti-A/Anti-B already present in blood 2-4 weeks → significant amount of Anti-Rh antibody Antibody type I g M(unable to cross placenta) I g G(able yo cross placenta) Transfusion Reaction

11. Rh incompatibility in Pregnancy There is a great complication due to Rh incompatibility arises when an Rh-negative mother carries an Rh-positive fetus. Small amounts of fetal blood leak into the maternal circulation at the time of delivery, and mothers develop significant titers of anti-Rh antibodies during postpartum period. If the mothers carry Rh positive fetus for the second time, the anti-Rh agglutinins will cross the placenta(as these are I g G) and cause hemolysis and various forms of hemolytic disease of the newborn (erythroblastosis fetalis)(HDN). For this the infant may die in uterus or may develop severe anemia , severe jaundice , and edema ( hydrops fetalis ).

12. Rh incompatibility in Pregnancy Rh-positive is dominant over Rh-negative

13. Severe Jaundice

14. Hydrops fetalis

15. Summary Rh antigens, present on the surface of RBC cell membrane are very significant factor for blood grouping. Out of about 49 types of Rh antigens D antigen is most important factor for antigenicity of Rh factor. It is very important to cross check the Rh group of donor and recipient before blood transfusion. We have to be aware of Rh incompatibility in pregnancy.

16. Ganong’s Review of Medical Physiology , 24 th edition, Tata McGraw Hill Principles of Physiology, Debasis Pramanik , 5 th edition, Jaypee Human Physiology , Lauralee Sherwood, 9 th edition, Cengage Learning Textbook of Medical Physiology, Guyton & Hall 13 th edition, ELSEVIER Internet resources

17. THANK YOU