How is haemophilia passed on?
Haemophilia is an inherited condition and occurs in families; however, in 1/3 of cases it appears in families with no previous history of the disorder. The genetic alteration causing haemophilia is passed down from parent to child through generations.
Read more - can females have haemophilia?
- Men with haemophilia will pass the gene alteration on to their daughters but not their sons.
- Women who carry the gene alteration can pass it on to their sons and daughters.
- Sons with the gene alteration will have haemophilia.
- Most women and girls who carry the gene alteration have normal clotting factor levels. Around 20-30% have reduced clotting factor levels. Sometimes their factor levels are low enought to be classified as having haemophilia, usually mild haemophilia. In a few very rare cases girls and women can have extremely low factor levels and have severe haemophilia.
The diagrams below may assist in understanding inheritance in haemophilia.
- The red males have haemophilia
- The red and blue females carry the gene alteration and some may also have haemophilia. They have one X chromosome with the gene alteration and one unaltered X chromosome.
Date last reviewed: May 2022
Important Note: This information was developed by Haemophilia Foundation Australia for education and information purposes only and does not replace advice from a treating health professional. Always see your health care provider for assessment and advice about your individual health before taking action or relying on published information.
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