CDE Nomenclature (Fisher-Race)
Definition
The modern standard notation for Rh antigens, naming three antithetical pairs: C/c, D (no d), and E/e. Haplotypes such as CDe (R1), cDE (R2), and cde (r) describe the combination of alleles on one chromosome. The notation aligns directly with the RHD and RHCE gene structure.
- System
- Fisher-Race Rh notation
- Antigen pairs
- C/c, D (no d), E/e
- Example haplotypes
- CDe (R1), cDE (R2), cde (r)
- Genetic basis
- Aligns with RHD and RHCE gene structure
Common questions
Why is there no lowercase 'd' antigen in this system despite the notation implying one?+
The 'd' was originally proposed as the antithetical allele to D by analogy with the other pairs, but no corresponding d antigen exists, so 'd' simply denotes the absence of D at that locus rather than a distinct antigen product.
Why does Rh haplotype notation matter in forensic or paternity blood typing?+
Before DNA profiling became routine, Rh haplotype combinations contributed to exclusionary blood group panels, and the CDE notation remains relevant background for interpreting older case records and for transfusion medicine contexts that intersect with forensic casework.
Related terms
- D Antigen
- The most immunogenic Rh antigen, encoded by the RHD gene. Its presence defines Rh-positive; its absence defines Rh-negative. No naturally occurring anti-D...
- Indirect Antiglobulin Test (IAT)
- A two-stage serological test in which IgG antibody is incubated with red cells, unbound antibody is washed away, and anti-human globulin (Coombs...
- Rh-Hr Nomenclature (Wiener)
- An earlier notation system using alphanumeric agglutinogen codes (R0, R1, R2, Rz, r, r', r'', ry) for Rh haplotypes. Wiener's R1 corresponds...
- RHD Genotyping
- PCR-based molecular typing of the RHD gene to determine D antigen status from DNA, including from dried biological evidence where serological red...
- Weak D (Formerly Du)
- A reduced-expression variant of the D antigen that does not agglutinate red cells with standard IgM anti-D reagent in the direct test...