If a mother is affected by an X-linked dominant condition and the father is not, which children can inherit the condition? only males
neither males nor females
both males and females
only females

both males and females

Explanation:

The sex chromosomes in male and female humans are X and Y chromosomes. X-linked traits are those traits which are associated with the X- chromosome.

According to the question, the trait is passed on a X-linked dominant condition, which means that the possession or not of the condition is dependent on the presence of the dominant X-chromosome. The dominant X-chromosome will always express itself even when in an heterozygous state with a normal X-chromosome i.e Xx. Hence, only a individual recessive for the X-chromosome will be normal.

A mother that is affected by the X-dominant condition will either possess a; XX or Xx genotype while a father that is normal (not affected) will possess a (xY) genotype. Since the mother passes one of her X chromosomes to her sons and the other to her daughters, both male and female children will be affected by the condition.

N.B: If the mother is heterozygous for the affected X-chromosome (Xx), half of her sons and half of her daughters will inherit the condition but if the mother contains two dominant X-chromosomes (XX), all of her sons and daughters will inherit the condition.