Question

Study the given pedigree chart in which neither of the parents shows the trait but the trait is present in both male and female children.

Answer the following questions: 
(a) Write the trait, also explain the inheritance of such trait in the progeny on the basis of given pedigree chart. 
(b) Give one example of such trait in human beings.

Hint:

In autosomal recessive inheritance, both parents must be carriers (heterozygous) for the trait to appear in the offspring, with a 25\% chance for each child to be affected.

Answer 1

Step 1: For (a), the trait is recessive since neither parent shows the trait (they are carriers), but it appears in both male and female children. Both parents must be heterozygous (Aa), and the children with the trait are homozygous recessive (aa). The inheritance follows an autosomal recessive pattern, where the probability of the offspring inheriting the trait (aa) is 25% when both parents are carriers.
Step 2: For (b), an example of such a trait in humans is sickle cell anemia, which is an autosomal recessive disorder. Individuals must inherit two recessive alleles (ss) to express the trait, while carriers (Ss) do not show symptoms.
Thus, the trait is autosomal recessive, and sickle cell anemia is an example.