Genetic Testing Disease Risk Profiling Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disorder in which digestive and respiratory organs produce large amounts of thick, sticky mucus. The epithelial cells that line the lungs and digestive system have difficulty functioning, leading to excessive mucus production.

Cystic fibrosis is most often diagnosed in childhood, often after failure to thrive is noted. Failure to thrive (difficulty growing, gaining weight and retaining nutrients) can have many causes, but it is often an initial diagnosis for a child with cystic fibrosis. This is because cystic fibrosis in the pancreas can hinder food digestion, and CF most often strikes the lungs and the pancreas.

In the lungs, cystic fibrosis leads to breathing difficulties, infections and a progressive loss of lung capacity, often accompanied by a chronic cough.

Causes of Cystic Fibrosis

Chromosomal genes manage specific functions in our bodies. Chromosome 7’s gene produces a protein called a cystic fibrosis transmembrane regulator. When the DNA level of chromosome 7 is mutated, the CF transmembrane regulator protein becomes absent. This protein deficiency is what results in cystic fibrosis.

When a child is diagnosed with CF, parents may wonder why they are healthy when their child has a genetic disorder. Chances are neither of them was aware that they were both genetic carriers of the mutated gene on chromosome 7 that leads to cystic fibrosis. It is easy to miss because a carrier has no symptoms of the disease.

Some doctors estimate that up to 12 million people in the United States are carriers for the cystic fibrosis. Unless they have a child with another carrier or get genetic testing, the majority will never know about the cystic fibrosis DNA marker they possess. However, being a carrier does not make having a child with CF a certainty. In fact, the chances of having a baby without the condition are three times greater than having a baby with CF.

Statistically, Caucasians are the most likely to develop cystic fibrosis, while Asians are the least likely to develop the disease. However, people of every nationality have been known to develop CF, so no ethnic background eliminates the possibility entirely.

Cystic Fibrosis - Genetics and Cystic Fibrosis

Diagnosing Cystic Fibrosis

Most people with cystic fibrosis develop symptoms of the condition before age three. By age 10, symptoms are usually chronic. Few adults with CF live past their forties. Aggressive treatment can extend a CF sufferer’s lifespan, but early diagnosis is crucial. The sooner the disease is detected, the longer the patient’s projected life.

Pediatricians usually diagnose cystic fibrosis by testing the child’s perspiration. This test measures the amount of chloride in the sweat. High numbers usually mean a diagnosis of CF.

Genetic testing is another route to diagnosis. However, the genetics of cystic fibrosis are somewhat mysterious. Roughly 1200 genetic mutations exist that can lead to CF, and not all are known or mapped. Therefore, genetic testing can fail to lead to a diagnosis – even if the condition exists – 10 to 20 percent of the time. Genetic testing to see if both parents carry the mutated chromosome 7 gene is an option for those who want to test before or during pregnancy. If both parents are carriers, they will be prepared knowing their child has a 50 percent chance of also carrying the mutated gene.

Measuring the levels of immunoreactive trypsinogen is another prenatal test for cystic fibrosis that can also be effective for newborns. If the levels are high, cystic fibrosis genetics are present.

Treating Cystic Fibrosis

Doctors often prescribe a variety of treatments once cystic fibrosis is diagnosed. The simplest therapy, with the least amount of intervention, is nutrition therapy – eating foods that are likely to cut down on the amount of mucus produced. Nutrition therapy is often combined with vitamin and mineral supplements.

Other treatments include:

  • aerosol medications
  • antibiotics
  • enzyme replacements (to make up for the pancreas’ inability to produce those enzymes)
  • physical therapy for the chest
  • therapy to clean out the lungs.

Although cystic fibrosis can be a frightening diagnosis, knowledge is the surest path to a good prognosis.

Resources

DNA Direct (2006).What is cystic fibrosis? Retrieved September 17, 2008, from the DNA Direct Web site: http://www.dnadirect.com/patients/tests/cystic_fibrosis/more_about/what_is_CF.jsp.

IACFA (2007). Introduction to cystic fibrosis (CF). Retrieved September 17, 2008, from the IACFA Web site: http://www.iacfa.org/.

Pinkerton, Kent (n.d.). Chomosome 7 and cystic fibrosis. Retrieved January 9, 2009, from the Ezine Articles Web site: http://ezinearticles.com/?Chromosome-7-and-Cystic-Fibrosis