Geneticist Questions Hemophilia

My sister has hemophillia. Should she have a baby?

My sister has hemophillia. Are there chances that it could spread to her child? Are there risks if she's pregnant?

2 Answers

Hemophilia A is an X-linked recessive disorder. Your sister's sex chromosome is XX, and for her to have hemophilia, both of her X chromosomes must have the abnormal hemophilia gene. She will contribute one of those abnormal X chromosomes to each of her children.
Since males have a single X chromosome, all of her male children will be affected.
Since females have two X chromosomes, all of her daughters would be carriers of the disease, but none of them would be affected unless they happen to inherit an abnormal X chromosome from their father.
Yes she can have a baby. She should see a reproductive endocrinologist before conceiving to try to maximize her baby not being affected. There is technology that can test eggs and sperm in vitro to her have an unaffected baby.