Question

A normal woman is married to a man having hypertrichosis. They got one daughter and one son. What would be the possibility of their daughter to show a hypertrichosis condition?
A. 0%
B. 25%
C. 50%
D. 75%

Answer 1

Hint: Gene responsible for hypertrichosis disease is present on the non-homologous part of the Y-chromosome. This gene can be inherited by the offspring from the father.

Complete Step by Step Answer:
Hypertrichosis is the condition in males, where they show excessive hair growth on the ear. It is a Y-linked gene. A condition is considered Y-linked if the diseased gene is present on a Y sex chromosome. The inheritance of Hypertrichosis is controlled by genes that are present on the non-homologous part of the Y-chromosome. The inheritance trait is from father to son.
As it is present on the Y chromosome, only males can have and express this gene. Females can not carry or express this gene. Hence only the male descendants of the affected generation will carry and usually express the hypertrichosis gene as females do not possess a non-homologous Y chromosome.
Hence even if a normal woman marries a man having hypertrichosis, the daughter will not possess or express the hypertrichosis gene. But the son will possess or usually express the hypertrichosis gene. Son might have hypertrichosis disease. Hence, the possibility that the daughter will have hypertrichosis disease is 0%.

Hence, The correct option is A.

Note: Hypertrichosis is a Y-linked disease. But there are some other diseases that are X-linked. While considering X-linked diseases, keep in mind that the X chromosome can be obtained either from the mother or father. Hence, in the case of X-lined diseases, it is not always the case that the offspring will have that disease.