Question

both parents of a newborn are heterozygous for an autosomal dominant genetic disorder. what are the odds that the newborn would also display the disorder? 0/4 1/4 1/2 3/4

Explanation:

Step1: Set up allele symbols

Let the dominant allele be \(A\) and the recessive allele be \(a\). The parents are both heterozygous, so their genotypes are \(Aa\).

Step2: Create a Punnett - square

The possible gametes from each parent are \(A\) and \(a\). The Punnett - square has the following combinations:

	A	a
a	Aa	aa

Step3: Determine genotypes showing the disorder

For an autosomal dominant disorder, genotypes \(AA\), \(Aa\) will show the disorder. There are 3 genotypes (\(AA\), \(Aa\), \(Aa\)) out of 4 total genotypes (\(AA\), \(Aa\), \(Aa\), \(aa\)) that will show the disorder.

Answer:

D. 3/4