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