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 SystemsA 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 d...