Association of Duffy blood groups with the sickle cell trait.

Among a small group of Saudi Arabs the Duffy blood group (Fy(a-b-)) was found to be associated with the sickle cell trait more often than could be explained by random gene combination thus supporting the concept that African gene flow brought the sickle cell trait to the Arabian peninsula. Based on recent observations concerning the possible role of Fy(a-b-) as a resistance factor against vivax malaria, it is proposed that the gene combination AS FyFy is likely to be selected in areas where falciparum and vivax infections are endemic and mixed infections occur frequently.