What is the pattern of sex linked inheritance?

Answer 1

In humans sex linked traits are passed on the X chromosome. (For the purpose of this discussion the trait being passed is recessive.)

This means that a male parent cannot pass the characteristic on to his male offspring, but he can pass the trait on to his female offspring.

The female parent can pass the trait on to any of her offspring.

Both parents must carry the allele for the sex-linked trait (and pass it on) in order for a female child to have the characteristic.

Male children that get the trait from their mother will have the trait no matter what the genetics of the father.

If the female parent is heterozygous for the trait 50% of her male children will have the characteristic no matter the father's genetics for that trait.

Assuming that the characteristic is not lethal and both parents are "carriers" (keep in mind that the father displays the trait and a heterozygous mother will not)...

50% of the sons will have the trait, 50% of the sons will not have the trait, 50% of the daughters will be homozygous for the trait and 50% will by heterozygous "carriers".

Answer 2

Sex-linked inheritance is a pattern where genes are located on the sex chromosomes (X and Y) and exhibit different inheritance patterns in males and females. For example, X-linked recessive disorders are more commonly expressed in males because they only need one copy of the mutated gene on their single X chromosome to show the phenotype. In contrast, females need two copies of the mutated gene as they have two X chromosomes.