What is the most probable genotype for a 25-year-old woman requiring RBCs if her antibody panel is positive?

To determine the most probable genotype for a 25-year-old woman requiring red blood cells (RBCs) when her antibody panel is positive, it's essential to understand the context in which blood group antigens and antibodies interact.

A positive antibody panel indicates that the individual has developed antibodies against certain red blood cell antigens. This suggests that the woman likely has a genotype that corresponds with the antigens she may lack, prompting her immune system to produce antibodies against those specific antigens.

Choosing the genotype R1R1 implies that the woman has two copies of the R1 allele, leading her to express the D antigen of the Rh system prominently. When a person with this genotype is exposed to other Rh antigens (like Doris), which can occur through pregnancy or transfusion, her immune system may develop antibodies against those absent antigens, resulting in a positive antibody panel.

The other genotypes listed might not align as closely with a positive antibody panel given the common practices in blood transfusion and pregnancy. For instance, rr indicates a lack of the D antigen, so it's unlikely she would have developed antibodies against it. Similarly, R0r and r'r' genotypes may not induce a positive antibody panel for the same reasons—they either do not