Question

If a father is affected by an X-linked dominant condition and the mother is not, which children can inherit the condition?

only males
neither males nor females
only females
O both males and females

Answer 1

only females

Step-by-step explanation:

In humans, sex chromosomes in males and females are different. The sex chromosomes found in humans are X and Y chromosomes. X-linked trait is a trait which is inherited on the X- chromosome. According to the question, the trait is passed on a X-linked dominant condition, which means the condition is inherited on the abnormal dominant X-chromosome that will express itself even when in an heterozygous state with a normal X-chromosome.

Hence, a father affected by the condition will have a genotype; XY while a mother that does not have the condition will have a genotype: xx (two normal x chromosomes). Since the Father can only pass his X chromosome to his daughters and never his sons, all his daughters will inherit the condition (see the punnet square in attached image).

N.B: None of the sons will inherit the condition since the mother will pass normal X-chromosomes (x) to her sons.