Background and objectives: The two Rhesus proteins, RhD and RhCE, constitute one of the clinically most relevant blood group antigen system. In the last two years, the understanding of RH molecular genetics has increased considerably. The state of the current knowledge was briefly summarised.
Materials and methods: Recent reviews, original work since 1999 and own results were utilised.
Results: The structure of the RH gene locus comprising RHD, RHCE and SMP1 was presented. True RHD genotyping became feasible by establishing the molecular basis of the most prevalent RH haplotype in whites harbouring the RHD gene deletion and of the RHD pseudogene RHD psi in Africans. Molecular and serologic characteristics of weak D and partial D alleles were compared. Closely related alleles for both, weak D and partial D, were collated as examples contributing to the understanding of RH phylogeny.
Conclusion: The RH gene locus is a model system for molecular polymorphism in clustered genes and suitable for studying molecular evolution in humans. It lends itself for developing molecular diagnostics because its genetics is appropriately complex and challenging; yet the expressed phenotypes have been studied for decades and are well understood. Legal and ethical issues that are rightfully of public concern would not be infringed if RH genotyping will be attempted on a massive scale.