1. SECTIONS:
2. preface & acknowledgements
3. genetics at a glance
4. contacts, support & testing
5. testing & pregnancy
6. newborn screening
7. cancer in the family
8. cardiovascular conditions
9. chromosomal conditions
10. clotting & bleeding conditions
11. cystic fibrosis
12. diabetes
13. fragile X syndrome and other causes of developmental delay
14. haemoglobinopathies
15. hereditary haemochromatosis
16. neurofibromatosis
17. neurological conditions
18. psychiatric conditions
19. genetics in practice
20. emerging genetic technologies
21. glossary

Genetics

1. Both haemophilia A and B follow an X-linked recessive pattern of inheritance.
2. Therefore females who are carriers have a 50% risk of passing the mutation on to their sons (who would then be affected with the condition) and daughters (who would then be carriers)
3. Haemophilia A is caused by low or absent factor VIII.
4. Haemophilia B is caused by low or absent factor IX.
5. The factor VIII and factor IX genes are found on the X chromosome, very close to each another.
6. A large number of different mutations occur in these genes and unrelated families with haemophilia A or B generally have different mutations.
7. Different mutations in the factor VIII or factor IX genes have been identified that cause differing severity of haemophilia A or B respectively.
8. The inheritance pattern may appear to look autosomal dominant in some families as up to 10% of women who are carriers can have mild bleeding symptoms.

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