Cystic Fibrosis: Sweat Chloride Test

CF is caused by a mutation in the cystic fibrosis transmembrane conductance regulator (CTFR) gene, which encodes a chloride ion channel that regulates osmotic balance across the epithelium through the transport of sodium ions and water4. Mutations

Cystic Fibrosis is an inherited condition. However, the gene for Cystic Fibrosis is recessive and

CF affects people of all the racial and ethnic groups but is most common among Caucasians. CF ranks the most common life-threatening genetic disease among this ethnicity. Approximately 1 out of every 15,000 African-Americans

Cystic Fibrosis is a chromosomal abnormality, meaning that one of the 23 pairs of chromosomes are not what they are supposed to be. A person without Cystic Fibrosis has a gene in chromosome 7, which produces a normal and substantial amount of protein called Cystic Fibrosis transmembrane regulator (CFTR), which in turn produces thin and watery mucus. A person with Cystic Fibrosis has a gene in chromosome 7, which produces either abnormal CFTR protein or no CFTR protein at all, which causes the body to produce thick and sticky mucus. People who are born with Cystic Fibrosis have two copies of the gene. One gene is received by each parent. In most cases, parents of people with Cystic Fibrosis, usually both carry the gene, however, the Cystic Fibrosis gene they are carry is recessive compared to the normal gene, allowing the normal gene it take over due to its dominance. This means that they do not have Cystic Fibrosis themselves. According to Cystic Fibrosis Queensland (2015) there is a one in four chance a person will have Cystic Fibrosis, a two in four chance that person will have the gene but not the disease and there is a one in four chance that the person will not have the disease or gene at all. The Cystic Fibrosis gene is easily passed on, however, the disorder not so much. The disorder is only passed on if a person obtains both the Cystic Fibrosis genes from their parents.

Cystic fibrosis is a genetic disease that is programmed in the victim’s DNA. It is passed on from parents who are both carriers of the defective gene. This genetic disorder affects the respiratory and digestive systems. People who suffer from cystic fibrosis usually inherit a defective gene on chromosome 7 called CFTR (cystic fibrosis transmembrane conductance regulator). Below is a diagram showing how cystic fibrosis is passed on from carrier parents to a child. The diagram shows that when a child is born by two parents who are both carriers of the CFTR defective gene, there is a one in four chance of being born with cystic fibrosis, there is a 2 in 4 chance of being a carrier or a 1 in

It is caused when an individual inherits a faulty gene, CFTR, from each parent ("What Is Cystic Fibrosis?," 2013). It is the most common lethal genetic disease that affects white children, impacting more than 30,000 children and young adults in the United States (Kowalczyk, 2014, p. 75), (Jr., 2014).

Nonetheless, the disease is most common among Caucasians of Northern European descent. Latinos and American Indians are commonly affected too (NHBLI, 2013). According to Beery and Workman (2012), the prevalence rate of CF in the United States among Caucasians is 1 in 3000 live births, whereas a carrier status is estimated to be at 1 in 20 to 30 Caucasian Americans (p. 192). To contrast, the probability of CF in Hispanic American populations is 1 in 13, 500 and 1 in 15,100 for African American. An estimated 70, 000 individuals suffer from cystic fibrosis worldwide with 30,000 of that total residing in the United States. In addition, approximately 1,000 new cases are diagnosed each year (Schechter,

“About 1 in 4,000 children in the United States are born with CF” (Crosta, 2009) and “one in every 3,600 children born in Canada [have] cystic fibrosis” ("Cystic fibrosis Canada," 2011). According to several resources a consensus has formed which proposes that people with northern European ancestry, specifically those that are white, are more likely to be carriers of the disease and thus more at risk of having children with the mutated gene. This risk is even more likely if the other parent of the child is a carrier. Another risk factor for CF is “family history, since the disease is hereditary it increases they likely hood of

Cystic Fibrosis can cause problems in the reproductive system. Cystic Fibrosis patients have many more sexual reproduction problems than a healthy human. In males with CF, they are likely to be infertile because of the tube connecting the testes and the vas deferens is missing or blocked with mucus. In women with CF, pregnancy can be a lot more difficult. Pregnancy can worsen the symptoms of Cystic Fibrosis. Women with CF may also be less fertile than women without CF. Women with CF should always consult with a doctor to know all of the possible risks. In order to get CF, both partners must be a carrier because the CF gene is recessive. If someone is a carrier, they could pass it on to their own child. Cystic Fibrosis tends to run in families, since it is an inherited disease. It is also most common in Caucasians.

The gene that’s responsible for causing Cystic Fibrosis is on chromosome 7. The most common

Cystic Fibrosis (CF) is the most common fatal genetic disease in the United States today. CF is an autosomal recessive disease that occurs approximately one out of 3,300 live births (Cystic Fibrosis Foundation, 1998). Autosomal means that the gene for CF is not carried on the sex chromosomes and males and females are both afflicted

This is still one of the most widely used tests because researchers still do not know exactly which gene is the defective Cystic Fibrosis gene ("Cystic,” Hereditary 47). Patients are usually diagnosed by the age of two but, a few rare causes are not diagnosed until the age of eighteen ("Cystic," umm.edu 1). Since symptoms usually appear early in life patients that are not diagnosed until later in life often have more mild forms of Cystic Fibrosis (Silverstein, Silverstein, and Silverstein 1; "Cystic," umm.edu 1). Luckily today children with Cystic Fibrosis are diagnosed early, in the nineteen-forties children often died from Cystic Fibrosis before they were old enough to attend school ("About" 1). Even though testing for Cystic Fibrosis is exceedingly simple the list of complications and illnesses associated with Cystic Fibrosis is extensive.

Here are some other changes affecting CF patients: Crackles, non-productive or productive cough, physical changes to the chest cavity, cyanosis, and clubbing of the fingernails. Genetic testing should be done since cystic fibrosis is an inherited disorder. Those affected with cystic fibrosis have parents “who do not have cystic fibrosis but are heterozygotes or carriers of the disease. A heterozygote has 1 dominant allele and 1 recessive allele.” (Grossman & Grossman, 2005, p. 46) My co-worker and her spouse are heterozygotes, and they have a 50/50 chance of having a cystic fibrosis child, they were not lucky with the odds and both their sons are affected with cystic fibrosis. These

Cystic Fibrosis (CF) is an autosomal recessive gene that causes a wide range of symptoms because there are over 1,000 changes or mutations that can occur within the cystic fibrosis transmembrane receptor (CFTR) protein. The CFTR protein is generally a chloride ion chain “regulated by cyclic adenosine monophosphate and therefore can act as a regulator of other electrolyte channels”(Grossman, S., & Grossman, L. 2005, p. 46). Typically this protein allows chloride ions to exit mucus-producing cells allowing water to flow in and thin the mucus. However, if the CFTR protein has been mutated, such as in cystic fibrosis, chloride ions cannot exit. This causes the mucus to thicken, become sticky, and obstruct the various channels it passes through. This build up of mucus also prevents bacteria from being cleaned from cells thoroughly increasing the patients risk for infections (Grossman, S., & Grossman, L. 2005). However, the severity of CF depends on whether the patients have complete or partial loss of the CFTR gene. If the person has the classic form of CF abnormalities of CFTR will commonly affect “…the respiratory, gastrointestinal, endocrine and metabolic, and genitourinary systems”(Schram, C. 2012). However, if people have atypical forms of CF their genetic disorder may only affect one of the organ systems and may not be found until the patient develops symptoms in their late childhood, early adolescence, or adulthood

This is a great improvement over survival rate of the 1950s with the life expectancy of 1 year or less for cystic fibrosis patients. Unfortunately, since it is a recessive genetic disease, there are many men and women who are carriers of the disease without actually having the disease themselves. If each parent is a non-affected carrier of cystic fibrosis, there is only a 25 percent chance of having a non-affected, non-carrier child and 50 percent chance of having a child that is a non-affected carrier of cystic fibrosis. Unfortunately there is also a 25 percent chance of having a child affected by cystic fibrosis. This makes prenatal genetic screening very important.