What are the characteristics of Xlinked recessive inheritanc

What are the characteristics of X-linked recessive inheritance? Why does a ton never inherit hit fathers defective X chromosome? What it required for a woman to display a sex-linked recessive trait? Return to the pedigree drawn earlier for Greg and Olga; mark those persons who are carriers of the factor viii deficiency gene. What is the chance that Olga carries the gene for factor viii deficiency? Calculate the probability that she will pass it to her offspring. Will male children be affected in a different way than female children? What is the chance that Greg carries the factor viii gene? Can he pass the gene on to his sons? His daughters? How will each be affected?

Solution

1. Characteristics of X linked recessive inheritance is as follows

* most affected individuals are male

* affected males come from heterozygous or affected mothers.

* sons of affected females should be affected

2. The son never inherits his father\'s defective X chromosome because both the parents contribute their gametes equally during Progeny generation. Thus, since only the father has a Y chromosome, for a son, the Y chromosome will be contributed by the father. This is an X linked inheritance. So even if the father would have a defective X chromosome , it will not be inherited by the son, but might get inherited by the daughter.

3. For a women to have a sex linked recessive trait, I.e. X linked recessive trait, it is necessary that she should inherit at least one of the X chromosomes , from either the mother or the father which would be carrier or a defective chromosome. Presence of only one defective X chromosome would make the women having a sex linked recessive trait.

Questions 4-6 can only be answered when the pedigree is shown.