Rh System
Definition
A blood group system defined by antigens on two proteins encoded by the RHD and RHCE genes on chromosome 1. The clinically most important antigen is D, which determines Rh-positive or Rh-negative status.
- Genetic basis
- RHD and RHCE genes on chromosome 1
- Most important antigen
- D antigen (determines Rh-positive or Rh-negative status)
- Discovery
- Identified by Landsteiner and Wiener in 1940
Common questions
What determines if someone is Rh-positive or Rh-negative?+
The presence or absence of the D antigen decides it. If you have the D antigen on your red blood cells, you're Rh-positive. If you lack it, you're Rh-negative. This antigen sits on proteins made by the RHD and RHCE genes on chromosome 1.
Why does the Rh system matter in forensic work?+
Blood groups, including the Rh system, are used in biological profiling and paternity cases. The D antigen is the most clinically important marker in this system, making Rh status a key piece of blood evidence. Knowing someone's Rh status can narrow suspect pools or link samples.
What is the D antigen?+
The D antigen is the primary marker that defines Rh status. It's a protein structure on red blood cells controlled by genes on chromosome 1. Its presence triggers a positive classification, its absence a negative one.
Related terms
- MNS System
- A blood group system comprising M and N antigens on glycophorin A (GYPA) and S and s antigens on glycophorin B (GYPB)....
- ABO System
- The blood-group classification described by Karl Landsteiner in 1901: groups A, B, AB, and O, defined by antigens on red-cell surfaces and...
- Agglutination
- Clumping of red cells that occurs when antibodies in serum bind to incompatible antigens on the cell surface, cross-linking cells into visible...
- Antibody (Isohaemagglutinin)
- An immunoglobulin in plasma directed against red-cell antigens the host does not carry. Group O serum carries anti-A and anti-B; group AB...
- Antigen
- A molecule recognised by the adaptive immune system through specific binding to an antibody or T-cell receptor. Defined by immunogenicity (capacity to...
- Antigen Degradation Rate
- The rate at which an antigen becomes undetectable on a dried stain, driven by protein denaturation, microbial protease activity, UV exposure, and...
- Antithetical Antigens
- Pairs of antigens where carrying one typically excludes the other on the same protein: C and c, E and e in the...
- Bombay Phenotype (Oh, Hh)
- Y. M. Bhende, 1952, K.E.M. Hospital Mumbai. Homozygous absence of the H antigen, so neither A nor B can be expressed; types...
- Discriminating Power
- The statistical ability of a typing system to distinguish one individual from another in a given population. Expressed as the probability that...
- Glycophorin
- A family of heavily sialylated red-cell glycoproteins. Glycophorin A carries M and N antigens; glycophorin B carries S and s antigens. Both...
- ISBT
- International Society of Blood Transfusion. The authority that catalogues and numbers the 35+ recognised blood group systems.
- Secretor Status
- A genetic trait that determines whether a person expresses their ABO blood group antigens in secreted body fluids such as saliva, semen,...
Explained in these topics
- Blood Group Systems in Forensic Science: ABO, Rh, MNS and BeyondLandsteiner and Wiener, 1940; clinical importance established by Levine and Stetson, 1939 (haemolytic disease of the newborn). D antigen presence defines Rh-po...
- Rh, MNS, and Other Blood Group Systems