## What is the probability that a son will have hemophilia?

1 in 4

Each daughter has a 1 in 2 (50%) chance of getting her mother’s hemophilia allele and being heterozygous. Overall, there is a 1 in 4 (25%) chance for each pregnancy that the baby will be a son with hemophilia and a 1 in 4 (25%) chance that the baby will be a heterozygous daughter.

## Can males carry hemophilia?

A male can have hemophilia if he inherits an affected X chromosome (an X chromosome with a mutation in the gene that causes hemophilia) from his mother.

**What is the probability that their first son will have hemophilia?**

Each son has a 25% probability of having hemophilia, and each daughter also has a 25% probability of having hemophilia. The order of birth does not affect the probability of having hemophilia.

**What is the probability that their first son will have?**

Assume that a man with hemophilia marries a normal woman whose father had hemophilia. Each son has a 25% probability of having hemophilia, and each daughter also has a 25% probability of having hemophilia. The order of birth does not affect the probability of having hemophilia. Since the normal woman’s father had hemophilia, she is a carrier.

### Can a father have a daughter with hemophilia?

All daughters will carry the hemophilia gene. No sons will have hemophilia. In this example, the father does not have hemophilia, and the mother does not carry the hemophilia gene.

### How is the inherited form of hemophilia inherited?

How Hemophilia is Inherited. There is a 50% chance that each son will have hemophilia. There is a 50% chance that each daughter will be a carrier of the hemophilia gene. In this example, the father has hemophilia, and the mother does not carry the hemophilia gene. All daughters will carry the hemophilia gene. No sons will have hemophilia.

Each son has a 25% probability of having hemophilia, and each daughter also has a 25% probability of having hemophilia. The order of birth does not affect the probability of having hemophilia.

Assume that a man with hemophilia marries a normal woman whose father had hemophilia. Each son has a 25% probability of having hemophilia, and each daughter also has a 25% probability of having hemophilia. The order of birth does not affect the probability of having hemophilia. Since the normal woman’s father had hemophilia, she is a carrier.

All daughters will carry the hemophilia gene. No sons will have hemophilia. In this example, the father does not have hemophilia, and the mother does not carry the hemophilia gene.

How Hemophilia is Inherited. There is a 50% chance that each son will have hemophilia. There is a 50% chance that each daughter will be a carrier of the hemophilia gene. In this example, the father has hemophilia, and the mother does not carry the hemophilia gene. All daughters will carry the hemophilia gene. No sons will have hemophilia.