Heterozygote Advantage in Disease Resistance May Explain Enigmatic Coexistence of Rh+ and Rh- Blood Groups in Humans

A new study published online on January 26, 2016 in PLoS ONE shows that the incidence and morbidity of many diseases and disorders correlate negatively with frequencies of Rh+ heterozygotes (i.e., the carriers of one copy of the gene for Rh positivity and one copy of the gene for Rh negativity) in the population of individual countries. At the same time, the disease burden associated with the same disorders correlated positively with frequency of Rh- subjects in individual countries. Together with the observed worse health status and higher incidence of many disorders in Rh- subjects published by the same research team last autumn, this result probably solves the 80-years-old enigma of coexistence of carriers of two variants of Rhesus gene in the same population. Rhesus factor polymorphism has been an evolutionary puzzle since its discovery in 1939. Carriers of the rarer allele should be eliminated by selection against Rhesus positive children born to Rhesus negative mothers. The new open-access PLOS ONE article is titled “Heterozygote Advantage Probably Maintains Rhesus Factor Blood Group Polymorphism: Ecological Regression Study.” Professor Jaroslav Flegr, Division of Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic is the author of the PLOS ONE paper and he said the following: “One enigma has been probably solved, however, two new [ones] have arisen. The first one is: how is it possible that the correlation of the disease burden and the frequency of particular genotypes have not been described much earlier when all necessary data are available at World Health Organization pages and the analyses can be performed within a few hours. Similarly, data showing worse health status of Rh-negative subjects are available in many databases, including the large Scandinavian nationwide databases.
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