Question

What are the genotypes of the parents shown in this pedigree if the disorder is a recessive disorder? What are the genotypes of the parents shown in this pedigree if the disorder is a recessive disorder?

both parents have the disorder

both parents are DD

both parents do not have the disorder

both parents are dd

Answer 1

If the disorder has an autosomal recessive inheritance pattern, according to the family tree both parents do not have the disorder, but are carriers.

Step-by-step explanation:

When a disorder or disease is recessive it requires two alleles with the disorder to manifest. In this case, according to the pedigree, both parents must be heterozygous carriers and not present the disorder.

Parents

♂ Dd

♀ Dd

Both without disorder but presenting the altered gene, which makes them carriers.

Alleles D d

D DD Dd

d Dd dd

The offspring of these parents have a 50% chance of being carriers without the disorder, 25% non-carriers, and 25% with the disorder.

In the event that either parent was DD, there would be a 50% chance of carriers without the disorder and no chance of offspring with the disorder, which has a recessive inheritance pattern.