Question

A woman has an X-linked condition on one of her X chromosomes. This chromosome can be inherited by
A. Only grandchildren
B. Only daughter
C. Both sons and daughters
D. Only sons

Answer 1

X-linked or sex-linked is recessive genetic disorders, which are inherited through a genetic defect on an X chromosome.

Complete answer:
X-linked inheritance means that the gene causing the trait or the disorder is located on the X chromosome. X-linked recessive traits possess three unique patterns:
->Fathers cannot pass X-linked recessive traits to their sons because fathers give Y chromosomes to their sons.
->X-linked recessive traits are more commonly expressed in males than females.
->X-linked recessive traits tend to skip generations, meaning an affected grandfather will not have an affected son but could have an affected grandson through his daughter.

Option a: X-linked inheritance means that the gene causing the trait or the disorder is located on the X chromosome. The condition can be carried/transmitted by the son as well as the daughters since the X’ gamete can be involved in the development of a boy X’Y (X’ from mother and Y from father) or a girl X’X (X’ from mother and X from father). This is an incorrect option.
Option b: X-linked inheritance means that the gene causing the trait or the disorder is located on the X chromosome. The condition can be carried/transmitted by the son as well as the daughters. Therefore, this is an incorrect option.
Option c: The woman has an X-linked condition on one of her X chromosomes This means she is carrying an X-linked condition on one of the X chromosomes. The genotype is X X’. The gametes will be X and X’. The condition can be carried/transmitted by the son as well as the daughters since the X’ gamete can be involved in the development of a boy X’Y (X’ from mother and Y from father) or a girl X’X (X’ from mother and X from father). Therefore, this is the correct option.
Option d: Woman is carrying an X-linked condition on one of the X chromosomes. The genotype is X X’. The gametes will be X and X’. The condition can be carried/transmitted by the son as well as the daughters since the X’ gamete can be involved in the development of a boy X’Y (X’ from mother and Y from father) or a girl X’X (X’ from mother and X from father). Therefore, this is an incorrect option.

Note: It is to be noted that X-linked recessive traits are more commonly expressed in males than females. It is due to the fact that males possess only a single X chromosome, and therefore require only one mutated X in order to be affected. Women possess two X chromosomes and thus must receive two of the mutated recessive X chromosomes.