Alors voici pour les ignorants (qui savent pourtant parler Anglais) :
The Duffy Antigen System sur Wikipedia :
The Duffy antigen system is a blood system in which a pair of proteins appears on the outside of red blood cells. It was named after the patient in which it was discovered.[1]
A person who has "Duffy negative" blood (no Duffy antigen naturally present) may be allergic, perhaps seriously allergic, to a blood transfusion which is "Duffy positive" (has this pair of proteins). Nearly all Caucasians are Duffy-positive, and a majority of those of African descent are Duffy-negative.[2] Since most Duffy-negative people are of African origin, this is one reason why encouraging blood donations from people of African origins is critically important to the health of other people of the same race"
La transfusion sanguine entre un Africain Duffy négatif et un Européen Duffy positif est impossible, car elle peut provoquer une sévère réaction allergique.