**Question:** In a case of disputed paternity, father's blood group is A, mother's blood group is B, the child's blood group may be: Karnataka 07

**Core Concept:** Blood group antigens are inherited independently.

**Why the Correct Answer is Right:** In blood grouping, the blood types are determined based on the presence or absence of specific antigens on the surface of red blood cells. In this scenario, the father has blood group A, and the mother has blood group B. Since blood group antigens are inherited independently, there are four possible combinations of blood groups for the child:

1. The child could inherit the father's blood group A (A+), which is the correct answer.
2. The child could inherit the mother's blood group B (B+).
3. The child could have both father's and mother's blood groups (A+ and B+, resulting in type AB).
4. The child could lack both father's and mother's blood groups (O+, which is the absence of both A and B antigens).

**Why Each Wrong Option is Incorrect:**

A. This option is incorrect because the child could inherit the father's blood group A (A+) alone. According to blood group inheritance principles, there is a 50% chance of the child having blood group A and a 50% chance of the child not having blood group A (O+).

B. This option is incorrect because the child could inherit the mother's blood group B (B+) alone. Similar to option A, there is a 50% chance of the child having blood group B and a 50% chance of the child not having blood group B (O+).

C. This option is incorrect because the child could have both father's and mother's blood groups (AB). Inheritance of blood groups is determined independently, which means that there is a 25% chance of the child having both blood groups A and B (AB). However, in this scenario, both father and mother have non-identical blood groups (A and B), which makes this option unlikely and not a correct answer.

D. This option is incorrect because the child could lack both father's and mother's blood groups (O). In this scenario, both father and mother have non-identical blood groups (A and B), which makes this option unlikely and not a correct answer.

**Clinical Pearl:** Understanding blood group inheritance is crucial for diagnosing blood transfusion reactions, resolving medical disputes (like the one described), and preventing transfusion errors. The ABO blood group system is the most common blood group system, and its inheritance pattern is independent inheritance, meaning the blood groups are determined independently of one another. This means that the child's blood group will not be AB, as both parents have non-identical blood groups.

**Correct Answer: D.** The child could lack both father's and mother's blood groups (O). In this scenario, both father and mother have non-identical blood groups (A and B), which makes option D unlikely and correct.

**Why it is important for medical professionals:** Under