Cystic Fibrosis

Human Hereditary Assignment

Names and Causes

Cystic fibrosis, also known as CF and Mucoviscidosis, is caused by mutations in the cystic fibrosis conductance regulator gene located on chromosome 7. (Hamosh 0)
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The gene that causes cystic fibrosis can mutate in over 1000 ways, so the symptoms of cystic fibrosis can vary widely. Malnutrition, abdominal cramps, growth retardation, and coughing are all commonly associated with cystic fibrosis. However, people with this disease also have very salty sweat, and testing its salinity is a common and reliable diagnostic tool. Elevated trypsin levels in the blood are a way that newborns are often screened for the disease. (Cystic Fibrosis World 2)

Prenatal Tests

In 1986, Boue et al. reported on prenatal diagnostic studies in 200 pregnancies with a presumed 1-in-4 risk of recurrence of cystic fibrosis. (Hamosh 60)

Number of People Affected

In the United States, the disease affects about one in every 3,900 newborns, and it is estimated that approximately 30,000 Americans are afflicted with this disease. (Cobb 2)

Can anyone get it? How is it Inherited?

Cystic fibrosis is a homozygous recessive genetic disorder. In this type of disorder, both parents must carry the allele for cystic fibrosis. If two parents who each carry the defective copy of the gene have a child, there is approximately a 25% chance that their offspring will have the disease. (Cobb 3)
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What kind of Medical Assistance is Required by People who have the Disease?

In 1938, American physician Dorothy Hansine Andersen identified cystic fibrosis as a disease. The primary treatment options to treat the symptoms of cystic fibrosis, until most recently were antibiotics and physical therapy. In 1989, scientists at the University of Michigan and the Hospital for Sick Children in Toronto, Ontario, Canada, made a huge advance when they identified the gene that causes cystic fibrosis and the CFTR protein. This improved understanding of the disease made it possible for scientists at the Cystic Fibrosis Center in North Carolina to breed mice that showed symptoms of human cystic fibrosis in 1992. (Cobb 5)

The medical assistance required for people with cystic fibrosis are to alleviate symptoms of the mucus build-up in the lungs. Large doses of antibiotics are given to persons with cystic fibrosis in order to combat the lung infections and to prevent a severe, life-threatening infection. On a predetermined schedule, some people undergo a course of antibiotics four times a year. (Cobb 11)

What Further Medical Assistance will be Needed as the Child Grows Older?

Further medical assistance will be needed as the child grows older, each day, most people with CF do airway clearance to help loosen and clear thick mucus that can build up in the lungs; take inhaled medicines, including antibiotics, to help keep the airways clear; and take pancreatic enzyme supplements to improve absorption of vital nutrients. (Foundation treatment 3)

What Would be the Long-Term Outlook for a Child with Cystic Fibrosis?

The long-term outlook for a child with cystic fibrosis would most likely include treatment on a daily basis, and the average life expectancy would be about 40 years. (Cystic Fibrosis World 3)

Are there any Treatments or Cures?

Cystic fibrosis can be treated, but it cannot yet be cured. Physicians often prescribe antihistamines and decongestants to open air passages. Coughing as well as physical therapy can help loosen mucus in the trachea and lungs. Aerosol medications, including hypertonic saline and dornase alfa, can also help release secretions and facilitate breathing. A wide variety of antibiotics, both oral and inhaled, can help treat pneumonia and other infections as well. Studies have also shown that the over-the-counter anti-inflammatory drug, ibuprofen, can slow pulmonary decline. Supplementary digestive enzymes can improve nutrition, as can feeding tubes in more severe cases. Surgery can sometimes help with sinus infections and obstructions, and a full lung transplant can offer a temporary improvement in respiratory function. Liver and pancreas transplants can often replace organs that have been destroyed by cystic fibrosis. (Cystic Fibrosis World 10)

Could this Disorder have been Prevented?

The only way to prevent a child from having Cystic Fibrosis is for at least one of the parents not to carry the defective copy of the gene—which would require any two parents that do both carry the defective copy of the gene to not have a child together (but each parent could still have a child if they married/had a child with someone else). (Cobb 3)

Could Someone who has the Disorder have Children in the Future? Would those Children be Affected?

Someone with cystic fibrosis would be able to have children in the future, but the child/children might be affected if the other parent had the disease as well. (Cobb 3)

What is the Current Status of Research on this Disorder?

The cause of many CF cases have been identified as a number of defects on specific genes. Testing for the carriers of the disease have been made possible by detecting these locations of the genes. (individuals who have only one defective gene copy, and therefore have no symptoms themselves). Testing currently involves looking for about 30 out of the thousands of gene mutations that can increase the risk of passing on CF to a child. Current testing detects about 85 percent of the most common CF gene mutations. Testing involves extracting DNA from a person's blood, cheek cells, or saliva. Most health professionals feel that this detection rate is still too low, so expensive genetic testing is usually only performed on persons who have a familial history of CF or are Northern European by descent. Testing for the gene responsible for CF remains controversial at this time. In particular, testing parents prior to or during a pregnancy to determine their carrier status has resulted in controversy. (Cobb 18)

Is there a new Cure/Treatment for the Disorder Coming Soon?

Researchers are currently trying to figure out how to use viruses as carriers for the normal genes. In order to do this, some other current studies are underway to investigate the use of liposomes, or small microscopic spheres consisting of a fatty-substance called a lipid, to transport the corrected gene. Experimental gene therapies using both viruses and liposomes have proven relatively ineffective to date, because too few cells take the vector and express the desired gene. (Cobb 17)