question_answer

Study the given pedigree chart showing inheritance of sickle - cell anaemia and answer the questions that follow.

(i) Is the trait recessive or dominant?

(ii) Is the trait sex - linked or autosomal?

(iii) Give the genotype of the parents.

Answer:

This disease is controlled by a single pair of allele \[H{{b}^{A}}\] and \[H{{b}^{S}}\]. Only homozygous individuals for\[H{{b}^{S}}\]i.e. \[H{{b}^{S}}H{{b}^{S}}\]. Show the diseased phenotype. The heterozygous individuals are carriers \[(H{{b}^{A}},\,\,H{{b}^{S}})\]. Therefore.

(i) the trait is recessive.

(ii) the trait is autosomal in nature because its gene is present on autosomes.

(iii) the parents are heterozygous. The genotype of the parents would be\[H{{b}^{A}}H{{b}^{S}}\,\,and\,\,H{{b}^{A}}H{{b}^{S}}\].