Question

If both the parents are carriers for thalassaemia, the chances of an afflicted child to be born to them is:

• A. 25\%
• B. 50\%
• C. 75\%
• D. 100\%

Hint:

In autosomal recessive disorders, both parents must contribute a defective allele for the child to be affected.

Answer 1

The Correct Option is A

Thalassaemia is an autosomal recessive condition. When both parents are carriers (genotype \(Tt\)), the potential offspring genotypes are determined by the following Punnett Square: \[ \begin{array}{c|c|c} & T & t \\ \hline T & TT & Tt \\ \hline t & Tt & tt \\ \end{array} \] The resulting genotypes and their probabilities are:

• \(TT\): Normal (25%)
• \(Tt\): Carrier (50%)
• \(tt\): Afflicted (25%)