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A presentation about cystic fibrosis for a high school biology class.
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Cystic Fibrosis
Eric Simkins
Lesson Plan
Inheritance
• Is Autosomal Recessive– Carried on Autosomes– To be affected an individual must be
homozygous recessive.– Heterozygous individuals are carriers
• Meaning they are not affected by the disorder, but can pass it on to their children.
Inheritance
• If both parents are carriers:– 25% chance of having a child with CF.– 50% chance of having a child that will be a
carrier.– 25% chance of having a child who is not
affected and is not a carrier.
Physiological Cause of Symptoms
• The defective gene on chromosome 7 alters a protein that transports chloride ions into/out of cells.
• Chloride Ions (Cl-) are not absorbed into cells.
• Water is not absorbed by cells.• The cells produce too much
mucus.
Symptoms
• Respiratory Problems– Caused by excess mucus in the
respiratory tracts.– Coughing or wheezing– Recurring respiratory infections
Symptoms
• Digestive Problems– Caused by excess mucus
blocking ducts leading from the pancreas to duodenum.
– Greasy stools.– Clay colored stools that float.– Diarrhea– Weight loss– Slow growth
Symptoms• Abnormally salty tasting sweat.
– Due to excess salt in the sweat.
• Clubbing of the fingers or toes.– Fingertips or toes appear rounded or expanded.
• 90% of males with Cystic Fibrosis are sterile.– They have no vas deferens
Treatments
• Practice Airway Clearance Techniques• Mucolytics—inhaled drugs that thin mucus• Antibiotics to fight respiratory infections• Diet• Enzyme Supplements—to replace missing
digestive enzymes• Lung Transplant
Testing
• Genetic Carrier Testing—for adults
• Newborn Screening—not definitive, but recommended by the CFF.
• Sweat Testing—if symptoms are shown.
History
• 17th Century-1900’s—Stories, Songs, and Records depict people with the symptoms of CF.
• 1938—Dr. Dorothy Anderson records the first concrete description of CR.
• 1940’s—Dorothy Anderson and Dr. Hodges conclude it is passed by Mendelian recessive inheritance.
• 1950’s—Sweat Test is discovered and implemented.• 1989—CF gene identified on chromosome 7.
2004 CF Lecture
Other Info
• 1:3,500 in the US
• The Cystic Fibrosis Foundation
• The Mayo Clinic CF Site
Resources