We are back again! Sorry for the delay. Let me compensate you with a very useful explanation about blood groups and compatibility. The eternal confusion. Am I universal receptor? Who can donate blood to who?
There exist two different human blood group systems -actually there are 32, but those two are the most important ones-, ABO and Rh antigen.
First of all, all of you should know that the dominance in ABO group is A and B co-dominant and O recessive. It means that if we have AA or AO genotype, the phenotype will be A, if we have BB or BO the phenotype will be B, with OO we have O, and with AB the phenotype is AB.
In case of Rh we have positive (+) or negative (-) genotype, the positive is dominant and the negative recessive.
Knowing that, now... who can donate to who? Here there is a very clear table about that: