A gene is the basic unit of heredity. Genes are responsible for the physical characteristics that each person has (like eye color, facial features, and many health conditions). Each gene occupies a certain location on a chromosome (a thread-like material that is located in the nucleus of every single cell in the body). Chromosomes come in 23 pairs, and each chromosome carries thousands of genes. Show What happens?Each gene has a specific role in determining how a person's body is put together and how it functions. The role of a gene is determined by its individual DNA code (deoxyribonucleic acid, the chemical coding for a gene). DNA is made up of four building blocks called bases. These bases are joined in a specific order for each gene. When a change occurs in the arrangement of the bases, it can cause the gene not to work properly. What are genetic disorders?A structural gene change which can cause a disease or a birth defect is called a mutation. Genes are inherited in pairs, with one gene inherited from each parent to make the pair. Cystic fibrosis occurs when both genes in the pair have a mutation. A person with cystic fibrosis inherits one CF gene from each parent. Cystic fibrosis is a genetic disorder caused by inheriting a pair of genes that are mutated or not working properly. The Cystic Fibrosis GeneEveryone inherits two copies of the CFTR (cystic fibrosis transmembrane conductance regulator) gene. However, some of the inherited copies are mutations. To date, over 700 mutations of the CFTR gene have been identified. A person with CF inherits two mutated copies of the CFTR gene. These mutations can either be homozygous, the same, or heterozygous, different mutations. The most common mutation is delta F508, accounting for approximately 70% of all mutations. Those homozygous for this mutation tend to be pancreatic insufficient. What Does the Mutation Do?The CFTR gene is a protein that functions as a chloride channel. A chloride channel helps maintain the proper balance of salt and water within a cell. A mutation in CFTR causes a dysfunction of the salt and water balance. This causes dehydration of the secretions (thick mucous) and excessive loss of salt in sweat. What is a carrier?A carrier is a person who only has one copy of the mutated gene. The parents of a child with CF each carry one CF gene and one normal gene. They have no symptoms and no disease. How does CF occur?When each of the parents contributes a gene to their child, they could pass on either their CF gene or their non-CF gene. Each pregnancy could result in one of three outcomes:
People have cystic fibrosis (CF) because they have inherited a faulty gene from both of their parents. Find out more about the CF gene, genotypes and the different mutations that people with CF have.
Our page on how people with cystic fibrosis are diagnosed with the condition also includes information on newborn screening, carrier testing and late diagnosis.
Find out more about medication, exercise, nutrition, transplant and transition on our treatment page.
Explore our interactive body to find out all about the different ways CF affects the body, from the lungs and digestive system to the bones and the reproductive system. Your donation will make a difference:
When CFTR is defective other channels, including the outwardly rectifying chloride channel (ORCC), the epithelial sodium channel (ENaC), a potassium channel known as ROMK1 and a chloride/bicarbonate exchanger, do not work properly. In addition, other chloride channels present on the surface of epithelial cells may be affected in the CF airways. These “alternative” chloride channels have been proposed as a therapeutic target to enhance chloride transport. The ORCC is found on the surface of many epithelial cells. Normal CFTR facilitates the transport of adenosine triphosphate (ATP), an energy-carrying molecule, to the outside of the cell, activating ORCC. It is unknown whether CFTR itself or an associated channel actually transports the ATP. However, the mutant CFTR is not able to perform the function of transporting ATP. The ENaC, a sodium channel found on the surface of epithelial cells, is made up of four subunits: two alpha, one beta and one gamma. Each subunit consists of two transmembrane helices. CFTR also influences the function of ENaC in the lung by decreasing its activity, however, the mechanism by which this occurs is unclear. As suggested by its name, the chloride/bicarbonate exchanger transports one bicarbonate molecule out the cell for every chloride that it transports into the cell. The chloride is derived from the efflux of chloride through CFTR. Therefore, if CFTR is not functional the activity of this channel will be greatly reduced. Several other chloride channels are present on the cell surface. The one that may be most influenced by CFTR is the CaCC or calcium-activated chloride channel. The exact protein that creates this channel has yet to be defined. However, it is known that the channel is modulated by the P2Y2 receptor which is activated by ATP. Therefore, the activity of this channel could be influenced by decreased ATP associated with mutant CFTR..
CFTR regulates the function of other ion channels located within the cell membrane. |