Which of the following options represents the phenotype of the ABO group?

Appeared in: NHM UP Staff Nurse-2023 shift 1st

Explanation

The ABO blood group system has four possible phenotypes, which are the observable blood types: A, B, AB, and O.
A phenotype is the physical expression of a gene, determined in this case by the presence or absence of specific antigens (A and B) on the surface of red blood cells.
The AB phenotype is a result of codominance, where both A and B alleles are expressed, while the O phenotype is recessive, requiring two O alleles (OO).

Option B: This option is incomplete as it omits the AB blood type, which is a distinct phenotype resulting from the codominant expression of A and B alleles.
Option C: This option is incorrect because it only lists two of the four possible phenotypes, excluding the O and AB blood types.
Option D: This option represents only one of the four phenotypes and is therefore an incomplete answer.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain ABO blood group phenotypes as background academic context rather than a clinical decision trigger.
Understanding ABO phenotypes is critical for safe blood transfusions. Transfusing incompatible blood can cause a life-threatening acute hemolytic transfusion reaction.
Knowledge of blood groups is also essential in organ transplantation and for assessing the risk of hemolytic disease of the fetus and newborn (HDFN), although Rh factor incompatibility is a more common cause.
What if? If a patient with Type A blood (phenotype A) is incorrectly given Type B blood, the recipient's anti-B antibodies will attack the donor's red blood cells, leading to agglutination, hemolysis, and potentially fatal complications like kidney failure and shock.

How to Approach the Question

First, identify the key term in the question: 'phenotype'.
Recall the definition of phenotype: the observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences.
In the context of the ABO blood group, the phenotype is the actual blood type (A, B, AB, or O).
Contrast this with 'genotype,' which refers to the specific allele combination (e.g., AA, AO, BB, BO, AB, OO).
Evaluate the given options to find the one that lists all possible ABO phenotypes.
Option A includes A, B, AB, and O, which is the complete set. The other options are incomplete lists.

Concept Tested & Keywords

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E6 Physiology Essentials Sembulingam 10e Part 1 p. 147-149

E6 Harper's Illustrated Biochemistry2023 (pp 26-793 of 813) p. 644-646

E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY p. 137-139

Practise the full NHM UP Staff Nurse-2023 shift 1st

Attempt every question from this paper in a timed mock, then review the full solution for each one.