Rh System Antigens
The proteins which carry the Rh antigens are transmembrane proteins, whose structure suggest that they are ion channels. The main antigens are D, C, E, c and e, which are encoded by two adjacent gene loci, the RHD gene which encodes the RhD protein with the D antigen (and variants) and the RHCE gene which encodes the RhCE protein with the C, E, c and e antigens (and variants). There is no d antigen. Lowercase "d" indicates the absence of the D antigen (the gene is usually deleted or otherwise nonfunctional).
Rh phenotypes are readily identified by identifying the presence or absence of the Rh surface antigens. As can be seen in the table below, most of the Rh phenotypes can be produced by several different Rh genotypes. The exact genotype of any individual can only be identified by DNA analysis. Regarding patient treatment, only the phenotype is usually of any clinical significance to ensure a patient is not exposed to an antigen they are likely to develop antibodies against. A probable genotype may be speculated on, based on the statistical distributions of genotypes in the patient's place of origin.
| Phenotype expressed on cell | Genotype expressed in DNA | Prevalence (%) † | |
|---|---|---|---|
| Fisher-Race notation | Wiener notation | ||
| D+ C+ E+ c+ e+ (RhD+) | Dce/DCE | R0RZ | 0.0125 |
| Dce/dCE | R0rY | 0.0003 | |
| DCe/DcE | R1R2 | 11.8648 | |
| DCe/dcE | R1r’’ | 0.9992 | |
| DcE/dCe | R2r’ | 0.2775 | |
| DCE/dce | RZr | 0.1893 | |
| D+ C+ E+ c+ e- (RhD+) | DcE/DCE | R2RZ | 0.0687 |
| DcE/dCE | R2rY | 0.0014 | |
| DCE/dcE | RZr’’ | 0.0058 | |
| D+ C+ E+ c- e+ (RhD+) | DCe/dCE | R1rY | 0.0042 |
| DCE/dCe | RZr’ | 0.0048 | |
| DCe/DCE | R1RZ | 0.2048 | |
| D+ C+ E+ c- e- (RhD+) | DCE/DCE | RZRZ | 0.0006 |
| DCE/dCE | RZrY | <0.0001 | |
| D+ C+ E- c+ e+ (RhD+) | Dce/dCe | R0r’ | 0.0505 |
| DCe/dce | R1r | 32.6808 | |
| DCe/Dce | R1R0 | 2.1586 | |
| D+ C+ E- c- e+ (RhD+) | DCe/DCe | R1R1 | 17.6803 |
| DCe/dCe | R1r’ | 0.8270 | |
| D+ C- E+ c+ e+ (RhD+) | DcE/Dce | R2R0 | 0.7243 |
| Dce/dcE | R0r’’ | 0.0610 | |
| DcE/dce | R2r | 10.9657 | |
| D+ C- E+ c+ e- (RhD+) | DcE/DcE | R2R2 | 1.9906 |
| DcE/dcE | R2r’’ | 0.3353 | |
| D+ C- E- c+ e+ (RhD+) | Dce/Dce | R0R0 | 0.0659 |
| Dce/dce | R0r | 1.9950 | |
| D- C+ E+ c+ e+ (RhD-) | dce/dCE | rrY | 0.0039 |
| dCe/dcE | r’r’’ | 0.0234 | |
| D- C+ E+ c+ e- (RhD-) | dcE/dCE | r’’rY | 0.0001 |
| D- C+ E+ c- e+ (RhD-) | dCe/dCE | r’rY | 0.0001 |
| D- C+ E+ c- e- (RhD-) | dCE/dCE | rYrY | <0.0001 |
| D- C+ E- c+ e+ (RhD-) | dce/dCe | rr’ | 0.7644 |
| D- C+ E- c- e+ (RhD-) | dCe/dCe | r’r’ | 0.0097 |
| D- C- E+ c+ e+ (RhD-) | dce/dcE | rr’’ | 0.9235 |
| D- C- E+ c+ e- (RhD-) | dcE/dcE | r’’r’’ | 0.0141 |
| D- C- E- c+ e+ (RhD-) | dce/dce | rr | 15.1020 |
† Figures taken from a study performed in 1948 on a sample of 2000 people in the United Kingdom. Note that the R0 haplotype is much more common in people of sub-Saharan African origin.
| Rh Phenotype | CDE | Patients (%) | Donors (%) |
|---|---|---|---|
| R 1r |
CcDe | 37.4 | 33.0 |
| R 1R 2 |
CcDEe | 35.7 | 30.5 |
| R 1R 1 |
CDe | 5.7 | 21.8 |
| rr | ce | 10.3 | 11.6 |
| R 2r |
cDEe | 6.6 | 10.4 |
| R 0R 0 |
cDe | 2.8 | 2.7 |
| R 2R 2 |
cDE | 2.8 | 2.4 |
| rr’’ | cEe | – | 0.98 |
| R ZR Z |
CDE | – | 0.03 |
| rr’ | Cce | 0.8 | – |
Read more about this topic: Rh Blood Group System
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