Question

A child has sickle-cell disease ( ss ) but neither parent is ill. What must be true of her parents’ genotypes?

Answer 1

The parents must both have the recessive gene to have had the child with the disease.

Hopefully this helps! :)

Answer 2

Her parents are heterozygous carrier for the disease and have genotype "Ss"

Step-by-step explanation:

Sickle cell disease is a recessive disorder and is expressed in homozygous recessive genotype only.

Since the child is affected with sickle cell anemia, her genotype is "ss".

To get "ss" genotype, both her parents should have at least one copy of "s" allele. Since both the parents are not affected by the disease, they are heterozygous for the allele. Both the parents have genotype "Ss" and are serving as carriers for the disease.