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FPTT is a low-incidence Rh antigen associated with a "new" partial Rh D phenotype, DFR
1Medical Research Council Blood Group Unit, London, UK.
Background:
Several Rh D phenotypes with partial D antigens are recognized. Some partial D antigens are associated with low-incidence Rh antigens. New partial D antigens are revealed by an atypical pattern of reactions with anti-D.
Study Design And Methods:
The reactions of D variant cells with panels of monoclonal anti-D and with antibodies to low-incidence antigens were compared to those of known D categories to identify a new Rh D phenotype. The inheritance of partial D antigens was studied by Rh phenotyping of the families of the probands. Standard serologic methods were used and family data were analyzed.
Results:
A new Rh D phenotype, to be called DFR, was identified in 17 probands, two of whom had made anti-D. The partial D antigen carries epD3, epD4, and epD9 and lacks epD8. The presence of other D epitopes is ambiguous; different answers were obtained for the same sample with different monoclonal anti-D of the same apparent epitope specificity. The immunoglobulin class of the anti-D was important: IgG were more successful than IgM monoclonal anti-D in detecting the partial D of DFR. Family studies showed that DFR traveled with Ce more frequently than with cE. The low-incidence antigen FPTT (International Society of Blood Transfusion number 700048) was found on all DFR samples. Family studies demonstrated that FPTT is, as suspected, part of the complex Rh system.
Conclusion:
The partial D of the Rh D phenotype, DFR, is recognized by its pattern of reactions with monoclonal anti-D and its association with the low-incidence antigen FPTT, FPTT has now been numbered Rh50.
Insights
A new Rh D phenotype, DFR, was identified, characterized by specific partial D antigens and association with the low-incidence antigen FPTT (Rh50). This finding aids in understanding Rh D variations and their inheritance patterns.
Area of Science:
- Immunology
- Genetics
- Blood Transfusion Medicine
Background:
- The Rh blood group system features diverse D phenotypes with partial D antigens, some linked to low-incidence Rh antigens.
- Atypical reactions with anti-D antibodies can indicate novel partial D antigens.
Purpose of the Study:
- To identify and characterize a new Rh D phenotype using serological methods and family studies.
- To investigate the inheritance patterns of partial D antigens within families.
Main Methods:
- Comparative analysis of D variant cells with monoclonal anti-D and low-incidence antigen antibodies.
- Rh phenotyping of proband families to trace antigen inheritance.
- Standard serologic techniques and family data analysis.
Main Results:
- A novel Rh D phenotype, designated DFR, was identified in 17 individuals, two of whom produced anti-D.
- DFR phenotype expresses epD3, epD4, and epD9, while lacking epD8; other epitope expressions were ambiguous.
- The low-incidence antigen FPTT (Rh50) was consistently found on DFR samples, confirming its association with the Rh system.
- Family studies indicated DFR segregation with Ce more often than cE.
Conclusions:
- The DFR Rh D phenotype is defined by its unique reaction pattern with monoclonal anti-D and its association with the low-incidence antigen FPTT (Rh50).
- This discovery contributes to the detailed characterization of Rh D antigen complexity and its genetic transmission.