与性有关的疾病

Some inherited disorders are caused by mutations to a single gene. And when located on a sex chromosome, the disorder is said to be sex-linked. Depending on which sex chromosome the gene is located on and whether one or both copies are required for proper function, these disorders are considered either Y-linked, X-linked dominant or X-linked recessive.

First, Y-linked disorders such as Y chromosome infertility are caused by mutations on genes located on the Y chromosome and can only be passed down from father to son. Second, X-linked dominant disorders including Fragile X syndrome require only one copy of the mutated gene, affect both females and males and cannot be passed from fathers to sons. Lastly, X-linked recessive disorders affect males much more often because females need two copies of the mutated gene.

Yet, unaffected heterozygous women can be carriers and have a 50% chance to pass it on to their sons. For example, an X-linked recessive disorder called Duchenne Muscular Dystrophy or DMD almost exclusively affect boys. DMD is caused by mutations in the gene encoding dystrophin, a protein involved in the proper contraction and repair of skeletal and cardiac muscle cells. The