Question

In a cross between a male and female, both heterozygous for sickle cell anaemia gene, what percentage of the progeny will be diseased?

• A. 100%
• B. 50%
• C. 75%
• D. 25%

Answer 1

The correct option is D 25%

Sickle cell anaemia is an autosomal recessive genetic disorder, hence the probability of males and females inheriting the disease is equal.

Normal allele: HbA
Sickle-cell allele: HbS

Genotype of unaffected individuals (homozygous) - HbAHbA

Genotype of carriers, unaffected individuals (heterozygous) - HbAHbS

Genotype of affected individuals (homozygous) - HbSHbS

Considering the cross in which both the male and female are heterozygous for sickle cell anemia gene (As per the information given in the question),


Hence, if both male and female are heterozygous for sickle cell anaemia, then only 25% of the progeny will be diseased.