1. Sex-Linked Traits

2. The X and Y chromosomes determine gender, but they also carry other traits. These traits are called sex-linked. If the gene is on the X chromosome, it is X- linked. If the gene is on the Y chromosome, it is Y- linked.

3. Y-linked traits are rare and are only inherited by males. X-linked traits can be inherited by females and males.

4. Because females get 2 copies of the chromosome, they have a greater chance of inheriting a non-disease allele and not inheriting the disease. X H X h – carrier, no disease Because males only get one copy of the gene, they are more likely to show the disease. X h Y - disease

5. Carrier – someone who has the allele for the disease, but does not express it. Only women can be carriers of sex-linked diseases, men either have the disease or they don’t.