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

Cystic fibrosis

 

1. See Cystic fibrosis for more detailed information.
2. Cystic fibrosis (CF) is primarily a respiratory and gastrointestinal condition affecting approximately 1 in 2500 babies.
3. In CF there is reduced function of a protein (CFTR) involved in the transport of chloride ions, resulting in mucus plugging, infection and neutrophil-dominated inflammation in the lungs, and exocrine pancreatic
   insufficiency in at least 80% of cases.
4. CF follows an autosomal recessive pattern of inheritance.
5. Carriers for CF are asymptomatic.

 

Common clinical features

1. Frequent respiratory tract infections and later, chronic sinopulmonary disease
2. Malabsorption, with loose stools and failure to gain weight
3. Meconium ileus
4. Males have azospermia

 

Test

1. Newborn screening for CF is a three-step process as outlined in Figure 2 below. The first step is a screening test for immunoreactive trypsinogen (IRT), (an indirect measure of pancreatic injury that is present at birth in most newborns who have CF) on the dried blood spot specimen. In those with elevated IRT levels, the second step is to test for common mutations in the gene responsible for CF (ΔF508 is the most common – see Contacts, support and testing for an explanation of the terminology regarding mutations). The third step is a sweat test for those with heterozygous DNA results.

 

Figure 2

Newborn screening for CF

 

Treatment

1. Treatment includes monitoring of health, growth and development by a CF clinic in conjunction with the
   child’s paediatrician or GP, early treatment and prophylaxis for bacterial respiratory infections, physiotherapy, a high calorie diet and pancreatic enzyme replacement.
2. Early treatment can slow the progress of CF.

 

Implications for other family members

1. Each future sibling of a child with CF has a 1 in 4 chance of also inheriting the condition. Pre-implantation
   genetic diagnosis (PGD) and prenatal diagnostic testing using direct mutation analysis or linkage studies are available options (see Contacts, support and testing and Testing and pregnancy).
2. Relatives of a person with CF may be carriers for the condition and referral to Genetics Services for genetic counselling is recommended. For example, a healthy sibling of a person with CF has up to 2 in 3 chances of being a carrier for CF.
3. Similarly, relatives of CF mutation carriers may themselves be carriers for CF and referral is again appropriate.

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