Introduction
Cystic fibrosis is an inherited diseases characterized by the presence of abnormally thick mucus, leading to respiratory, digestive, and other problems. Caused by an defective inherited autosomal recessive gene. Results in abnormally thick mucus excreted by epithelial cells. The mucus clogs some of the bodies tracts leading to respiratory, gastrointestinal, heaptobiliary, reproductive, and sweat gland problems. Diagnosed by sweat test, prenatal diagnosis, immunoreactive typsinogen test (IRT), nasal potential difference (NPD) measurement, genetic testing, and pulmonary function tests. Doctors also use medical and family history. Treated by symptom treatments.
Principles
A certain protein named CFTR helps to transport chloride ions across cell membranes in secretory cells. The transport of chloride helps to transport water out of the cells and to keep the secretions thin. There is a defective gene, however, which damages the CFTR protein. This means that the chloride transport is damaged, which means that the water transport is damaged, which means that the secretions are not thinned, and are thus very thick.
Mucus is usually supposed to lubricate tubes. If, however, the mucus is abnormally thick as it is in cystic fibrosis, it clogs the tubes instead. Clogged tubes can have very bad effects, such as blocking air movement and blocking secretion movement. These are the problems experienced by cystic fibrosis patients.
Historical Aspects
An old proverb from northern Europe states “Woe to that child which when kissed on the forehead tastes salty. He is bewitched and soon must die.” This proverb refers to cystic fibrosis, in which the sweat of the patient tastes salty because of increased chloride levels.
Professor Fanconi, a Swiss physician, was the first to provide a clinical description of cystic fibrosis in 1936.
Dr. Dorothy Andersen of New York was the first to provide a pathological description of cystic fibrosis in 1938. She called it “cystic fibrosis of the pancreas.”
By 1946 it was understood that cystic fibrosis was inherited as a recessive trait.
In 1949 a Detroit doctor said that obstuction of the airways in progressive lung disaese was due to abnormal mucus.
In 1953, Dr. Paul di Sant’Agnese said that loss of salt to sweat was the reason for the deaths of many babies with cystic fibrosis during a heat wave in New York.
In 1989, Lap-Chee Tsui, John Riordan, and Francis COllins isoalted the gene responsible for CF.
Statistics
30,000 Americans have CF, 20,000 Europeans have CF, and 3,000 Canadians have CF. There are about 70,00 worldwide cases.
12 million Americans are CF carriers.
2,500 babies are born every year in the US with CF.
Cystic fibrosis is the #1 cause of death due to genetics in young people in the US.
90% of all cystic fibrosis cases are diagnosed before the age of 17.
Population Groups
Caucasians: 1 out of 1,600 babies born have cystic fibrosis.
African Americans: 1 out of 13,000 babies born have cystic fibrosis.
Asian Americans: 1 out of 50,000 babies born have cystic fibrosis.
Genetics
Cystic fibrosis is caused by a defective gene on chromosome 7. This defective leads to abnormalities in the protein known as CFTR (cystic fibrosis transmembrane regulator) whose job is to move chloride ions into the cell. Abnormal chloride ion movement leads to CF.
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