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Cystic fibrosis (CF) is a genetic disorder characterized by the production of sticky mucus which often clogs the lungs resulting in frequent infections, like bronchitis, pneumonia and sinusitis. Symptoms of lung infections in CF gene mutations include long term cough with phlegm, wheezing, and fever. The pancreas is also affected eventually leading to the blockage of digestive enzymes from going to the small intestines. Manifestation of digestive problems include diarrhea, weight loss, malnutrition, gas, severe constipation, and poor growth. Other complications of cystic fibrosis are diabetes, pancreatitis, development of gall stones and liver disease. Rectal prolapse, where the tissues in the rectal wall protrude out of the anus, may sometimes occur due to defecation problems and to the frequency of coughing.
In the United States, cystic fibrosis is among the most common causes of mortality in children.
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The gene closely related to the development of cystic fibrosis is the cystic fibrosis transmembrane regulator (CFTR) gene. Mutation in CFTR often results in the manifestation of cystic fibrosis symptoms resulting from lung problems and digestion problems. CFTR is found on the long arm of human chromosome 7.
The CF gene was first discovered in 1989 and after its discovery, more or less than 1000 CF gene mutations were identified. CFTR is a protein categorized as a traffic ATPase. These types of proteins are responsible in transporting essential molecules like metal cations, sugars, chloride, inorganic phosphate and peptides transversely to the cell membrane. It is especially important in the transport of chloride ions going in and out of the cells. The presence of chloride ions generally controls the water movement in tissues thus allowing the production of mucus that is thin and flows freely. When mutations in the CRTR gene occurs, the function of chloride channels present in the cells are affected, thus causing derangement in the regulation of chloride ion transport across the membrane of the cells. This often make cells that line the lungs and pancreas to produce sticky and thick mucus, futher resulting in clogging of their passageways.
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Other CFTR Gene Disorders
Aside from cystic fibrosis, alterations in the CFTR gene can cause congenital bilateral absence of vas deferens (CBAVD) in males. Sticky mucus that is produced by cystic fibrosis can sometimes clog the vas deferens of children, affecting its normal development. Affected male children can survive up to adulthood, and most of the problems with CBAVD usually arises during their productive years. CBAVD is frequently established when signs of azoospermia, where no sperms are present in the semen, occur. During physical examination the vas deferens could not be palpated and evidence of abnormalities may also appear after doing imaging studies.This is frequently the cause of infertility in males with cystic fibrosis. Some women with cystic fibrosis, may also experience infertility, but is less common in incidence.