Which statement about blood group genotypes is correct?

Which statement about blood group genotypes is correct?

• A. An individual with the BO genotype is homozygous for B antigen
• B. An individual with the BB genotype is homozygous for B antigen
• C. An individual with the OO genotype is heterozygous for O antigen
• D. An individual with the AB phenotype is homozygous for A and B antigens

Answer: (B)

The statement concerning the BB genotype being homozygous for B antigen is accurate because individuals with the BB genotype inherit two alleles for the B antigen, one from each parent. In the ABO blood group system, the A and B antigen genes are codominant, meaning that when an individual possesses two identical alleles, such as BB, they express the B antigen on their red blood cells. This fundamental genetic principle underlines how inherited traits manifest in observable blood group phenotypes. On the contrary, the other options misrepresent key concepts in blood group genetics. The BO genotype is not homozygous; rather, it represents heterozygosity, with one B allele and one O allele. An individual with an OO genotype is actually homozygous for the O antigen and does not express A or B antigens. Lastly, individuals with an AB phenotype carry both A and B antigens, but they are not homozygous; instead, they are heterozygous, showcasing the codominance of the A and B alleles. Understanding these genetic principles is crucial for correctly interpreting blood group inheritance and compatibility in transfusion medicine.

The statement concerning the BB genotype being homozygous for B antigen is accurate because individuals with the BB genotype inherit two alleles for the B antigen, one from each parent. In the ABO blood group system, the A and B antigen genes are codominant, meaning that when an individual possesses two identical alleles, such as BB, they express the B antigen on their red blood cells. This fundamental genetic principle underlines how inherited traits manifest in observable blood group phenotypes.

On the contrary, the other options misrepresent key concepts in blood group genetics. The BO genotype is not homozygous; rather, it represents heterozygosity, with one B allele and one O allele. An individual with an OO genotype is actually homozygous for the O antigen and does not express A or B antigens. Lastly, individuals with an AB phenotype carry both A and B antigens, but they are not homozygous; instead, they are heterozygous, showcasing the codominance of the A and B alleles. Understanding these genetic principles is crucial for correctly interpreting blood group inheritance and compatibility in transfusion medicine.