Which Rh chromosome is considered the rarest?

The Rh blood group system is genetically complex, with several different antigens that can be present on the surface of red blood cells. The antigens are primarily classified by the presence of the D, Cc, and E antigens, leading to a variety of Rh phenotypes.

The Rh phenotype characterized by the presence of the d allele is generally seen as more common in the populations due to the prevalence of the D antigen. In contrast, the phenotype associated with the CdE combination represents a rarer combination of these antigens. This is because it involves a particular arrangement of both C and e antigens along with the D antigen, occurring in fewer individuals compared to the more commonly encountered combinations of Rh blood types.

The rarity of the CdE phenotype can be attributed to genetic variations within different populations, where certain Rh phenotypes may be more prevalent due to evolutionary factors. This is why CdE is considered the rarest Rh type when assessed among the common Rh haplotypes. Understanding these genetic distributions in populations is crucial for blood transfusion compatibility and managing Rh incompatibility situations in pregnancy.