Genetics of Cystic Fibrosis

Cystic fibrosis is a genetic disorder that causes nutritional deficiencies and severe lung damage. This life-threatening condition is inherited and affects the cells that produce sweat, mucus, and digestive juices. This genetic disorder is not rare like most think, in fact it occurs in approximately one out of every 3,000 live births. Now that the genetics of cystic fibrosis are better understood, this disorder which used to take the lives of patients in their teens, rarely does anymore. Many patients are living well into their 50’s.

How Cystic Fibrosis is Inherited

This inheritance of this genetic disorder is called autosomal recessive. This means that the affected gene is present on the first 22 pairs of chromosomes. These do not determine gender which explains why both boys and girls are equally affected. The inheritance is recessive because two copies of the gene are required to have this condition, one from each parent. Once parents have one child with this disorder, there is 25 percent chance that every subsequent child they have will be born with cystic fibrosis.

Genes are found on the chromosomes. In normal people, there are 23 pairs of chromosomes for a total of 46 individual chromosomes. A gene called the cystic fibrosis transmembrane regulator (CFTR) is located on the seventh pair of chromosomes. When an error or mutation occurs in this gene cystic fibrosis occurs. More than 1,000 different mutations in this gene can result in cystic fibrosis. Caucasians and Ashkenazi Jews have the highest risk of having cystic fibrosis when there is no family history of the disorder.

Symptoms of Cystic Fibrosis

The symptoms of this genetic disorder are often broken down into respiratory symptoms and digestive symptoms. The respiratory symptoms include persistent cough, repeated lung infections, wheezing, and repeated sinus infections. The digestive symptoms include stools that are greasy and foul-smelling, distended abdomen due to constipation, poor growth and weight gain, and intestinal blockage (most often in newborns).

Treating Cystic Fibrosis

There is no cure for this genetic disorder, but there are treatments available to help reduce complications and ease symptoms. Medications such as antibiotics, bronchodilators, and mucus-thinning drugs can be prescribed to help treat a variety of associated respiratory ailments.

A variety of different therapies are available to help reduce some of the respiratory ailments. These include a chest clapper, breathing devices, and an inflatable vest.

Other procedures and surgeries can also be performed in more serious cases to help relieve the more serious symptoms and complications. These include a lung transplant, inserting a feeding tube, and bowel surgery.

Resources

Lucile Packard Children’s Hospital at Stanford. (2010). The Genetics of Cystic Fibrosis. Retrieved on March 31, 2010 from Lucile Packard Children’s Hospital at Stanford: https://www.lpch.org/diseasehealthinfo/healthlibrary/respire/cfgenetc.html

Mayo Clinic. (2010). Cystic Fibrosis. Retrieved on March 31, 2010 from the Mayo Clinic: https://www.mayoclinic.com/health/cystic-fibrosis/DS00287

Image Credits

Lung Diagram: LadyofHats – Wikimedia Commons