Question

When two sickle-cell carriers (HbA HbS) are crossed, what is the expected genotypic ratio of offspring?

Options

• 3 HbA HbA : 1 HbA HbS

• 1 HbA HbA : 3 HbA HbS : 1 HbS HbS

• 1 HbA HbA : 2 HbA HbS : 1 HbS HbS

• 1 HbA HbA : 1 HbA HbS : 2 HbS HbS

Answer 1

A cross between two heterozygous carriers (HbA HbS × HbA HbS) produces the typical Mendelian monohybrid ratio: 1 HbA HbA : 2 HbA HbS : 1 HbS HbS. The one-quarter homozygous normal, one-half heterozygous carrier, and one-quarter homozygous mutant offspring distribution reflects standard segregation of alleles during meiosis.