What is X-linked inheritance?
X-linked inheritance means that the gene alteration causing the trait or the disorder is located on the X chromosome. Remember, females have two X chromosomes, while males have one X and one Y. Mutations in X chromosome genes can be recessive or dominant. Their expression in females and males is not the same because the genes on the Y chromosome do not exactly pair up with the genes on the X. In general, X-linked recessive mutations are expressed in females only if a female has two copies of the mutation (one on each X chromosome). However, for males, if their only copy of the X chromosome contains a mutation, they will have the trait or disorder. To date, no cancer susceptibility genes have been identified on the X chromosome. However, research studies of families with a strong history of prostate cancer have found evidence that there might be a prostate cancer susceptibility gene on this chromosome.
