Caucasian people carries at least one of the fatal defective genes that causecystic fibrosis, CF, or mucoviscidosis (in Europe) although carriers don’t showany signs of the disease. Therefore, 10 million2 people carry the defective geneand aren’t aware of it. Consequently, it makes it one of the most common geneticdefect in the United States. CF is a autosomal recessive gene. That means thatit may, but doesn’t always skip generations.
In order to get this disease, bothparents must be carriers. If one parent has CF and the other one is not acarrier than there is a 100% chance that their child will be a carrier. If oneparent has CF and the other is a carrier than the child has a 50% chance ofhaving CF and a 50% chance of just being a carrier. If both parents are carriersthan their child will have a 25% of having CF, a 50% chance of being a carrierand a 25% chance of not being affected. CF is common in both males and females,there is not a specific sex that it is more common in. How does a person know ifthey have CF? There are many symptoms to this deadly disease including: saltytasting skin, constant coughing, large amounts of mucus, trouble gaining weight,frequent greasy, foul smelling bowel, growths in the nose (nasal polyps) andclubbed or enlarged fingertips and toe tips is another symptom.
Now there aremany tests that can be done to find put if a person has CF. One way which CF canbe detected is to observe the symptoms. A person doesn’t need to have all thesymptoms in order to have cystic fibrosis, but they usually show most of them.Another way are different genetic testing. Doctors can now do genetic testingfor CF, but about 10 years ago they couldn’t. In 1989, the location where the ofthe defective gene on chromosome number 7 is was discovered by Francis S.
Collins from University of Michigan. Tests can now be taken to see if an unbornchild is infected with CF such tests are amniocentesis, chronic villus biopsy3and a removal of cells from the embryo during invitro. Many years ago, New York4had a heat wave, and the hospitals became overwhelmed with dehydrated CFchildren. These children became dehydrated much quicker than children withoutthe disorder. Thus eventually resulting in the formation of the sweat test whichis now the standard test. Doctors place a pad or filter paper on a patients armor back.
A chemical called Pilocarpine, makes a burst of electricity to producemore sweat. Then the pad is wrapped in plastic and is sent to a lab to getanalyzed. The doctors then would look for a high chloride content in the sweat.Another test is a blood test that is administered 3 days after a baby is born.It is called Immunoreactive Trypsinogen5 if that comes back positive it is thendouble checked with a sweat test. Furthermore CF causes the sweat glands torelease about 5 times6 as much salt as a normal person would. This is why theskin of a CF patients may taste salty.
They don’t sweat more, but when theyperspire more salt is excreted. This causes the person to dehydrate. CF is adisorder that causes the body to produce larger amount of mucus than normal. Ina normal person, mucus in the lungs helps get rid of germs and bacteria in theair. In a CF patients the lungs become covered with a sticky mucus that is hardto remove and promotes infection from bacteria.
Over time infections cause thelungs to become extremely weak, therefore ending in respiratory failure. Also CFaffects the digestive tract. The overproduction of mucus causes the pancreaticducts to be clogged. Therefore preventing necessary enzymes to digest fats andproteins. Without those enzymes CF patients can’t gain weight. The undigestedproteins and fats pass right through the body creating smelly bowel. In somecases this malnutrition causes people to die when they are only children.
Alsoit is more common for people with cystic fibrosis to develop digestive tractcancer7. High levels of the protein CFTR (which the gene makes) are found in thedigestive tissues. Doctors explain this increased risk of cancer because CFinduces change in the digestive tract organs that causes the cell turnover.Patients with gastrointestinal tract problem should get examined for suchtumors. Women with CF can have children, but it is not very common. Giving birthis a vigorous process and puts the mother’s health at risk. It may also be hardfor a women to get pregnant though because the mucus blocks the sperm fromentering the uterus the to the fallopian tubes.
About 98% of men with CF areinfertile8. Even though sperm are produced, they can’t get to the semen becausethe vas deferens is blocked. In some new research, it has been thought that menwho are sterile have a different form of CF that doesn’t involve the digestivesystem and the lungs. There are now many drugs that are in the market and manymore that are in development. Treatments mainly depends on what organs areeffected.
The first new drug therapy in 30 years was approved by the Food andDrug Administration in December of 93′. It’s a mucus-thinning drug calledPulmozyme. Pulmozyme has reduced the number of respiratory infections andimproved lung function.
There is also postural drainage or thumps. Thistreatment is when the patient is hit on the back and chest with cupped hands toloosen the mucus so it can be coughed up easier. There are many antibiotics thathelp treat lung infections. Also medicated vapors are inhaled and open cloggedairways. Since mucus in the intestines causes the food not to get digested,there are enzyme supplements to help. Those enzymes allow patients to go back toa normal diet. Due to the high concentration of the enzymes the end result isdeterioration of the pancreas leading to diabetes.
With the supplements CFpatients can eat normal food. There are now many studies that the medicineibuprofen (Advil, Motrin IB, Nuprin) prevents serious damage to lungs inchildren who have CF. The trials involved 85 patients between the ages of 5 and39 with FEV1 equal or greater than 60%9. In this study patients that tookibuprofen had a slower rate of decline of FEV1.
Patients that took it for 4years consistently had even better results and showed best in patients under theage of 13. The dose of ibuprofen was selected between 50 and 100up/mL becausethe anti-neutrophil effects of ibuprofen are only attained at these levels.There are some side effects, including conjunctivitis (unknown reason) andepistaxi (due to the anti-platelet action in the ibuprofen. Doctors say that itis not sure if stomach pains are due to the ibuprofen, but to stay on themedicine and to take antacids with magnesium and aluminum and not thosecontaining calcium. In 1990 two teams of researchers were able to correct CFcells in a petri dish10.
The next huge step happened in 199311, when the firstexperimental dose of gene therapy was administered to a human. These weremilestones in finding a cure or a preventive treatment. They were huge stepsbecause it marked the first time that scientists were able to test newtechnology in people with the disease. Also in October of 93’12 scientists atthe University of Iowa made another big step, they determined that the CF genetreatment worked! It had repaired the defective CF cells. This too was the firsttime that the basic defect was corrected in people with the disease.
Doctors andscientists know that the gene number 7 is the gene that CF is found upon. Theyalso know that gene’s protein product most likely induces the movement ofchloride directly or indirectly. They named the protein ,cystic fibrosistransmembrane conductance regulator (CFTR). While scientists and doctors werelooking for the gene, they also discovered that there is an abnormality in theDNA of 70%13 of cystic fibrosis cases. That abnormality often called AF508mutation, is made of the deleting of 3 nucleotides from that gene, that thencauses the protein product to be missing an amino acid named phenylalanine atposition 508.
Doctors are now trying to get to this gene mutation and fix it.Scientists are trying to think of a way to administer healthy CFTR genes to thepatients through gene therapy. If all goes as planed the DNA injected will helpthe cells to make the normal CFTR protein and cystic fibrosis will then beterminated. Doctors have many “delivery vans” that deliver the goodgenes. Doctors transport them in viruses, fat capsules and synthetic vectors14.They are put in the body through the nose or bronchial tubes. Nine human genetherapy research studies are in the works as of now.
Six of these nine are usingthe “delivery vans” to deliver healthy genes to the lungs or the nose.In one study the patients are given repeated doses of the CF gene therapytreatment to the lungs. While other studies gives repeated doses of the genetherapy to the nasal tissue of the patients. The other studies are using the fatcapsules for delivery, another is making the fat capsule in air form and arebreathed in by the patients. Putting the good genes in AAV (adeno-associatedvirus) is another way of getting the genes in the body.
In the last study, arealso uses the AAV to get the healthy genes into the lungs. There are aboutninety people with CF who have gone through some sort of gene therapy.”There is a long way still to go before we have a cure for cystic fibrosis,but we are moving in the right direction,” says David Porteous of theMedical Research Council’s Human Genetics Units at Edinburgh University.Recently a grant15 has just been given to a company named Aradigm that might getus closer to a better delivery vector. Dr. Igor Gonda, Aradigm’s Vice Presidentof research and development says, “By combining gene therapy with the AERxdelivery system, our research could ultimately lead to a broadly-applicabletechnology for delivery of genes and olignucleotides to the respiratory tract.
Diseases which might be treated by such genetic therapies include respiratoryinfections, lung cancer, emphysema, asthma and cystic fibrosis.”16 Cysticfibrosis is a genetic disorder that affects not only it’s victims, but it’svictims family and friends. Thanks to modern medicine and new techniques, themedian survival rate has gone from 8 years old in 50’s to 30 years old in thelate 90’s17.
Unfortunately, all this new medication and discoveries has come tolate for many people. One such individual is Alex Deford. She died when she wasonly 8 years old.
Her father, Frank, wrote a book based on her life and theirmany struggles, from ignorant doctors who wouldn’t believe a dying child about acollapsed lung and the disease itself. Many times with any genetic disorder, theparents blame themselves. After all it was their bad genes that caused it.Actually, when Alex first went into the hospital to get a sweat test, it cameback negative, when in reality it was positive. That was back in the early 70’sthough. Now sweat tests have few oversights.
Cystic fibrosis is a disease thatdoesn’t take any prisoners. All victims will eventually die from complicationdue to CF. There are approximately 30,00018 children and adults that are livingwith this disorder.
Now that scientists have found the gene in which CF islocated, new medicines and new therapies will hopefully be invented. Perhaps inthe next century, we can say that cystic fibrosis is completely abolished. Maybethe new medications and therapies won’t have to be as painful as they are now.Why should these individuals with CF be made to suffer in order to get better.Frank Deford says about chest physiotherapy and the disease, “Two thousandstimes I had to beat my sick child, make her cry and plead…
and in the end forwhat?”Bibliography”About Cystic Fibrosis.” http://www.ai.mit.edu/people/mernst/cf/what-is-cf.htmlMarch 11, 1997.
Internet. “AKL And Cystic Fibrosis.” http://www.
lookup.com/Homepages/70590/AKL_CF.htmlMarch 11, 1997. Internet. “Aradigm Awarded Grant From National Institutesof Health.
” http://biz.yahoo.com/prnews/97/03/10/ardm_y0022_1.html March10, 1997. Internet.
“British Team Close to Cystic Fibrosis GeneTherapy.” http://www.yahoo.
com/headlines/970304/newsstories/cystic_1.htmlMarch 4, 1997. Interent. “CF Ibuprofen Lab: General Information forPhysicians.
htm April 7, 1997.Internet. “Cystic Fibrosis.” http://darwin.clas.
virgina.edu/rjh9u/cfsciam.htmlNovember 27, 1995. Internet.
Deford, Frank. Alex: The Life of a Child. New York:The Viking Press, 1983. “Facts about cystic fibrosis.” http://www.
cff.org/factsabo.htmSeptember 21, 1996.
Interent. “Gene Therapy.” http://www.cff.org/genether.htmSeptember 21, 1996.
Internet. “How is CF Diagnosed?” http://www.dal.ca/distsite/frank/cf-diag.htmlMarch 12, 1996. Interent.
“Medical Complications of Cystic Fibrosis.”http://www.ai.mit.
edu/people/mernst/cf/info-zone/med-compl.html March 11, 1997.Internet. Neglia, Joseph P., FitzSimmons, Stacey C.
, Maisonneuve, Patrick,Schoni, Martin H., Schoni-Affolter, Franzisca, Corey, Mary, and Lowenfels,Albert B. “The Risk of Cancer Among Patients with Cystic Fibrosis.”The New England Journal of Medicine 332.
8 (1995): 494-499. “Progress inCystic Fibrosis Research.” http://www.cfforg/progress.htm November 8, 1996.
Interent. Raloff, Janet “Ibuprofen Stalls Advance of Cystic Fibrosis.”Science News 147.13 (1995): 197.
Ramsey, Bonnie W. “Management of PulmonaryDisease in Patients with Cystic Fibrosis.” The New England Journal ofMedicine 335.3 (1996): 179-189. Silverstein, Alvin, Virgina Silverstein, andRobert Silverstein.
Cystic Fibrosis. Chicago: Franklin Watts, 1994. “Whatis CF?” http://www.dal.ca/distsite/frank/cf-basic.html July 17, 1996.Internet. “Why Does Someone Get CF?” http://www.dal.ca/distsite/frank/cf-why.htmlMarch 12, 1996. Interent.