EVOLUTION OF THE HUMAN RH (RHESUS) BLOOD-GROUP GENES - A 50-YEAR-OLD PREDICTION (PARTIALLY) FULFILLED

Almost exactly 50 years ago, R.A.Fisher and R.Race proposed a model fo r the evolution of the RH (rhesus) genes in which the less common hapl otypes were derived from the commoner ones by recombination, and in wh ich the gene order was D-C-E. No direct-evidence bearing on this model was available then, and has not been until now. Here we present evide nce for non-reciprocal intergenic exchange (gene conversion) occurring once in human history to generate the common RHCE allele, Ce, We have also used new polymorphisms to construct haplotypes which suggest tha t intragenic recombination played a major role in the generation of th e less common haplotypes, but only if RHD lies 3' of RHCE, i.e. the or der is C-E-D. We provide both genetic and physical evidence supporting this arrangement.