Principles of Inheritance and Variation Question 8
8. A woman has an X-linked condition on one of her $X$ chromosomes. This chromosome can be inherited by
(a) Only daughters
(b) Only sons
(c) Both sons and daughters
(d) Only grandchildren
Show Answer
Answer : c
Hints & Solution
(c) Woman acts as a carrier. Both son & daughter inherit X-chromosome. Although only son would be the diseased one.
$$\begin{gathered}X^c X \times X Y \\ \downarrow \\ X^c X \quad X^c Y X X \quad X Y\end{gathered}$$ Sex-linked diseases are passed down through families through one of the $X$ or $Y$ chromosomes. $X$ and $Y$ are sex chromosomes. Dominant inheritance occurs when an abnormal gene from one parent causes disease, even though the matching gene from the other parent is normal.
