Can a father with type O pos and mother produce child A B negative blood?
The AB blood type is formed when an A allele and a B allele are inherited from both parents. The O blood type is formed when two o alleles are inherited, and the negative Rh factor is inherited when two negative Rh alleles are inherited.
For a child to have type AB negative blood, both parents would have to carry both the A and B alleles, as well as the negative Rh allele. However since one parent has OO phenotype, it is not possible for them to produce child of AB blood group.