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. CF follows an autosomal recessive pattern of inheritance and is caused by mutations in the CFTR (cystic fibrosis transmembrane regulator) gene.
2. As is common with autosomal recessive conditions, when a family member is diagnosed with CF there is often no family history of the condition since the mutation has previously only been present in healthy carriers on each side of the family (see Genetics in practice).
3. CFTR regulates chloride and sodium transport in the epithelial surfaces of the airway, pancreatic and biliary ducts, the gastrointestinal tract, sweat ducts and the vas deferens. Pathogenic mutations either remove or reduce the function of CFTR gene.
4. There are more than 1500 known CFTR mutations, but not all will be associated with classical CF.
5. A carrier for CF, that is a person carrying only one mutated copy of the CFTR gene, will still produce sufficient amounts of the salt-transport protein for normal body function.
6. Where multiple family members are affected with CF they may appear to be scattered among or within generations depending upon whether two carriers for CF have had children.
7. Parents who are both carriers for a CFTR mutation associated with classical CF have a 1 in 4 chance of having a child with CF, in each pregnancy.
8. If only one parent is a carrier for a CFTR mutation, each child has 1 in 2 chance of being a carrier like the parent, and unaffected.
9. Carrier testing is accurate if the CFTR gene mutation in the family is known.
10. The most common mutation in the CFTR gene is known as ΔF508 (also written as delF508) that accounts for approximately 70% of all CF gene mutations in those of Northern European ancestry.
11. Laboratories test for varying numbers of the common mutations. Testing for 12 or more mutations covers at least 80% of possible mutations in Australian Caucasians. The rest of the mutations are extremely rare. Mutations that are common in populations other that those whose ancestry is Northern European may not be included in the panel of mutations that are routinely tested by laboratories.
12. In the absence of a family history of CF, a negative screen for CFTR gene mutations is reassuring, but cannot absolutely rule out the possibility of being a carrier as not all mutations can be tested. Therefore if a couple chooses screening for CF there is still a small risk of having a baby with CF if their carrier test is negative.

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