What is the inheritance pattern of hemophilia?

The inheritance pattern of hemophilia is X-linked recessive. This means that the gene responsible for hemophilia is located on the X chromosome. In this pattern, males are more frequently affected than females because they have only one X chromosome. If a male inherits the mutated gene on his X chromosome, he will express the condition. In contrast, females have two X chromosomes, so if they inherit one X chromosome with the mutation, they may not exhibit symptoms because the second, normal X chromosome can often compensate for the mutated one. However, females can be carriers of the hemophilia trait.

Additionally, since the gene is located on the X chromosome, it can be passed from affected mothers to their sons, who would be at risk of expressing the condition. Affected fathers can only pass their X chromosome with the mutation to their daughters, making them carriers, but cannot pass it to their sons, who inherit the father's Y chromosome instead. This X-linked inheritance pattern is characteristic of several conditions related to the blood-clotting process, including both hemophilia A and hemophilia B.