© R.J.Walters Ph.D. 1999
Autosomal recessive mutation on chromosome 7 that took 10 years to pinpoint.
Most common lethal inherited disease in the Western world.
In Caucasian population 1 in 2000 children will carry two defective copies of the CF gene.
One in 25 people in Britain carry one faulty copy of the gene.
Two carriers have a 1 in 4 chance of having a child with CF and 1 in 2 of a carrier.
Estimated 2 million carriers in GB and 8 million in US.
70% of CF cases result from the deletion of a single amino acid from position 508 (phenylalanine) in the protein chain.
Expected life span of CF homozygote has increased to over 30 due to improved health care.
Primary Questions
WHAT TISSUES DOES CF AFFECT IN THE BODY ?
WHAT ARE THE SYMPTOMS ASSOCIATED WITH CF ?
HOW DID WE DISCOVER IT ?
WHAT THERAPIES CAN BE DESIGNED TO TREAT CF ?
HOW CAN WE DETECT THE FAULTY GENE IN THE POPULATION ?
WHAT ARE THE SOCIAL DILEMMAS OF SCREENING FOR CF ?
What tissues does CF affect in the body?
CF creates problems primarily for the body's cells that line the lungs, intestines, pancreas, sweat glands and reproductive organs, known collectively as epithelia.
Epithelia transport nutrients, salt and water between body compartments.
In the 1950's CF was known to be associated with abnormal salt transport in the sweat glands, in 1983 Quinton discovered that a deficit in Cl- secretion was responsible.
What are the symptoms associated with CF ?
In the lung the secreted mucus is thick and poorly hydrated and is not cleared leading to a `crackling cough' and bacterial infections that destroy the lung tissue.
In the intestine and pancreas the deficit in the secretion of salt and water leads to the poor digestion and absorption of nutrients, resulting in poor growth and infection.
The defect in the reproductive system leads to infertility.
The social dilemmas of screening for CF
Tests do not reveal 15% of CF mutation carriers.
A study of 1700 pregnant women in Cambridge showed that:
A third of women would not terminate in the event of fetal abnormality; 7% felt that nobody should, and 10% would rather not know of an abnormality.
EUGENICS: Pressure to terminate to reduce health cost burden: £100,000 per CF patient.
Stigmatisation of carriers and reduced resources to those affected by disease.
False positives are disturbing and screening is playing `Russian roulette'.
Apparent non-paternity: up to 15% of the population tested reveal that the partner may not be the biological father.
How is the screening programme to be funded ?
CYSTIC FIBROSIS: Some key facts