They can not delevope anti-Fyb correct? or am I wrong?

If they are antigen negative then they should be able to make the corresponding antibody.

It depends on whether or not they are homozygous for the GATA-1 mutation gene.

If they have this mutation, then, very often, although not always, they carry the FYB gene, but, because of the mutation, the Fy( antigen is not expressed (specifically) on the red cells, but is expressed on other tissues. Therefore, the immune system does not recognise the Fy( antigen as foreign.

If they have this mutation, but DO NOT have the FYB gene, or if they DO NOT have the mutation and are genuinely Fy(a-b-), then David is absolutely correct, and they can make anti-Fyb (although they are far more likely to make anti-Fy3 in that case)!

Thank you Malcolm and David.

There's a good review on Duffy in this issue.

IMMUNOHEMATOLOGY, Volume 26, Number 2, 2010

Ajac, very good reading.