If a woman who is heterozygous for the sickle cell anaemia gene marries a normal homozygous man, what proportion of their children is expected to be carriers of the trait?

Step-by-step solution

Sickle cell anaemia is an autosomal recessive disorder. Let the normal allele be Hb^A and the sickle cell allele be Hb^S . The genotype of the heterozygous woman is Hb^A Hb^S . The genotype of the normal homozygous man is Hb^A Hb^A . The cross between them is Hb^A Hb^S Hb^A Hb^A . The gametes produced by the woman are Hb^A and Hb^S , while the man produces only Hb^A gametes. The possible genotypes of their children are Hb^A Hb^A (normal) and Hb^A Hb^S (carrier) in a 1:1 ratio. Therefore, the proportion of their chi