Question

Most pedigrees showing the hypothetical human trait show the following characteristics

• If a phenotypically normal woman with an affected father has children with an unaffected man, half of the sons and none of the daughters are affected.
• Affected females always have an affected father and an affected maternal grandfather.
• The trait is never passed from father to son.
What is the most likely mode of inheritance for this disorder?
a. Autosomal recessive
b. Autosomal dominant
c. X-linked recessive
d. X-linked dominant
e. Y-linked

Answer 1

The most likely mode of inheritance for this disorder is X-linked recessive. In X-linked recessive inheritance, males either have the disease or are genotypically normal, while females can be genotypically normal, carriers who are phenotypically normal, or affected with the disease. The trait is passed from affected females to their sons.

Step-by-step explanation:

The most likely mode of inheritance for this disorder is X-linked recessive (c).

In X-linked recessive inheritance, males either have the disease or are genotypically normal, while females can be genotypically normal, carriers who are phenotypically normal, or affected with the disease. Daughters can inherit the gene for an X-linked recessive illness when their mother is a carrier or affected, or their father is affected. The daughters will be affected by the disease only if they inherit an X-linked recessive gene from both parents.

For example, if a phenotypically normal woman with an affected father has children with an unaffected man, half of the sons and none of the daughters will be affected, which is consistent with X-linked recessive inheritance.