People with these CFTR mutations have milder lung disease and some pancreatic function which is why they tend to live much longer than those with more severe types of CF. Genotype refers to the genetic code in a cell.
Genotyping is the process in which a genetic mutation is identified through genetic testing. Phenotype refers to the way a genotype is expressed, such as hair color. In the case of CF, phenotype explains which symptoms are more or less severe in certain genotypes.
Theratyping refers to the process of identifying a genetic mutation based on how the body responds to available therapy. By providing your email address, you are agreeing to our privacy policy.
We never sell or share your email address. All rights reserved. Always consult your doctor about your medical conditions. Use of the site is conditional upon your acceptance of our terms of use. How Does Cystic Fibrosis Develop? By Editorial Team August 15, Share to Facebook Share to Twitter email print page Bookmark for later.
How is cystic fibrosis inherited? Why does this gene cause cystic fibrosis? This is called a trafficking defect. This is called a defective channel regulation.
This is called decreased channel conductance. The protein-building instructions spelled out in the CFTR gene tell the cell which of the 20 available amino acids to use at each position in the chain. If the CFTR gene has a nonsense mutation, the protein-building instructions contain an early stop signal that causes the production of the CFTR protein to stop prematurely. Therefore, the cell begins to build the CFTR protein normally until it reaches the early stop signal.
Because the cell stops reading the instructions before it finishes making the protein, no functional CFTR protein is produced. Watch this webcast starting at to see how a nonsense mutation affects production of the CFTR protein and how the mutation might be corrected to make normal CFTR protein.
Splice mutations interfere with the ability of the cell to correctly read the instructions for making the CFTR protein. In a healthy person, the instructions spelled out in a gene are interrupted by stretches of DNA letters that do not code for protein, like an article in a magazine might be interrupted by ads.
The beginning and end of these stretches of irrelevant letters are marked with a special signal. In order to make the protein, the cell copies the DNA letters into a similar alphabet called ribonucleic acid RNA , and then follows the signals to clip out all of the irrelevant letters -- as you might clip out the ads.
That way, the instructions can be read straight through from start to finish. A splice mutation changes the signal that tells the cell where the irrelevant letters in the instructions begin or end. When the cell tries to read its RNA copy of the instructions, it no longer can tell where to begin and end reading. As a result, the cell will either leave in some irrelevant letters, or remove some relevant ones. When the cell tries to follow the RNA instructions containing the irrelevant letters, or missing relevant ones, it will be unable to build a correct CFTR protein.
The CFTR protein is made up of 1, amino acids. It has to be the right shape to transport chloride. When a mutation causes an amino acid to be deleted or an incorrect amino acid to be added, the CFTR protein cannot form its correct 3-D shape and function properly.
These mutations are considered to be protein processing mutations. The most common CF mutation, Fdel, is primarily considered to be a processing mutation. The cell recognizes that the protein isn't the right shape and disposes of it. Although this drug combination is not a perfect fix, it helps the mutant CFTR protein to move some chloride.
This movement of chloride reduces the symptoms of CF. Watch the webcast starting at to learn more about CF protein processing mutations and how drugs such as CFTR modulators can help a person with one of these mutations.
The exact combination of mutations your genotype and other factors will dictate how severe the condition is for you, and which organs in the body are worst affected. The most common of this type of mutation is Fdel. If you would like to use the website you will need to read and accept the site usage agreements at the bottom of the home page.
On the next page the welcome page you can then enter your genetic variants into the search bars at the top of the page.
If you get stuck there are some video tutorials at the bottom of the welcome page guiding you through the site usage agreements and how to use the searches. Please remember that this information is not a substitute for information from your CF team, and is only a representation of the average health outcomes of people with your genotype, and cannot account for individual experience.
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. What are the causes of cystic fibrosis? What is a genotype? Types of mutation Genes instruct the body on how to make proteins and where to send them in cells in order for them to work.
Find out more about your genotype CFTR2 is a website that provides information about specific variants in the CF gene.
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