Question

homework - genetic disorders
analyze the pedigree which shows the inheritance pattern of an autosomal dominant genetic disorder.
key
affected male
affected female
normal male
normal female
if individual r was an affected female, what would be her genotype?
dd
dd
dd
she could be either dd or dd

Explanation:

Step1: Understand autosomal dominant inheritance

In autosomal dominant disorders, the presence of at least one dominant allele (D) causes the disorder. The normal genotype is \(dd\) (recessive - recessive).

Step2: Analyze the parents of individual R

The father of individual R is affected (\(Dd\) or \(DD\)), but since the mother is normal (\(dd\)). When crossing, if the father is \(Dd\) (probable as the mother is \(dd\) and there are normal children), using a Punnett square:

	\(D\)	\(d\)
\(d\)	\(Dd\)	\(dd\)

If the father was \(DD\), all children would be \(Dd\) (affected), but there are normal children. So the father must be \(Dd\).

Answer:

B. Dd