CFTR rs121912487: Understanding the DeltaF508 Mutation
The rs121912487 variant, commonly known as the DeltaF508 mutation, is the most frequent genetic alteration associated with cystic fibrosis. It involves a specific deletion in the CFTR gene that disrupts the production and function of a critical protein responsible for regulating chloride transport in the body.
What each genotype means
Typical CFTR function
This genotype indicates the absence of the F508del mutation on both copies of the CFTR gene. Individuals with this result do not carry this specific mutation, which is the most common cause of cystic fibrosis.
This is the most common genotype found in the general population across all ancestries.
Cystic fibrosis carrier status
This genotype indicates you are a carrier of the F508del mutation, also known as the DeltaF508 mutation. Carriers typically do not exhibit symptoms of cystic fibrosis, but they may pass this variant to their offspring. If you are planning a family, you may wish to discuss carrier screening options with a genetic counselor or clinician.
Carried by approximately 2% of individuals of European ancestry, with varying frequencies in other global populations.
Cystic fibrosis associated genotype
This genotype indicates the presence of the F508del mutation on both copies of the CFTR gene, which is the most common cause of cystic fibrosis. This mutation leads to the production of a misfolded protein that is largely degraded by the cell, resulting in impaired ion transport. Clinical outcomes can vary significantly between individuals, and you should consult with a specialist to discuss management and potential genotype-based therapies.
This genotype is rare in the general population and is primarily identified in individuals diagnosed with cystic fibrosis.
What is the rs121912487 Variant?
The variant identified as rs121912487 is a well-studied genetic change in the CFTR gene, located on chromosome 7. In scientific literature, it is widely referred to as the DeltaF508 mutation, which signifies the deletion of a single amino acid, phenylalanine, at position 508 of the CFTR protein. This specific change is classified as a class II mutation, meaning it causes the protein to fold incorrectly within the cell. Because the protein does not achieve its proper shape, the cell's quality control mechanisms typically identify it as defective and degrade it before it can reach the cell surface. This prevents the protein from performing its essential role in maintaining the balance of salt and water across cell membranes, which is a hallmark of the underlying biology of cystic fibrosis.
The Role of the CFTR Gene
The CFTR gene provides instructions for creating the cystic fibrosis transmembrane conductance regulator protein. This protein functions as a channel that transports negatively charged particles called chloride ions into and out of cells. This movement of chloride ions is vital for the production of thin, free-flowing mucus, which lubricates the linings of the lungs, pancreas, and other organs. When the CFTR protein is absent or dysfunctional, as is the case with the DeltaF508 mutation, the transport of chloride ions is impaired. This leads to the production of thick, sticky mucus that can clog airways and obstruct ducts in the pancreas. The resulting accumulation of mucus creates an environment that is prone to bacterial infections and can significantly impact the function of the respiratory and digestive systems.
Research and Clinical Significance
Research into rs121912487 is extensive, as it is the most common mutation linked to cystic fibrosis worldwide. Studies have consistently shown that individuals who inherit two copies of this mutation—one from each parent—are at a significantly higher risk of developing the clinical symptoms of cystic fibrosis. The evidence supporting this association is strong and well-documented by expert panels and clinical geneticists. Because this mutation prevents the protein from reaching the cell membrane, therapeutic research has focused on finding ways to help the protein fold correctly or to improve its function once it reaches the surface. It is important to note that while this variant is a primary focus of research, cystic fibrosis is a complex condition, and clinical outcomes can be influenced by other genetic and environmental factors. Always consult with a medical professional or a genetic counselor to understand how specific genetic findings relate to personal health.
Population Frequency
The DeltaF508 mutation is found in the general population, particularly among individuals of European descent. It is estimated that approximately 2% of the European population are carriers of this specific variant. Being a carrier means an individual has one copy of the mutation but typically does not exhibit the symptoms of cystic fibrosis, as they possess a second, functional copy of the CFTR gene. Because it is an autosomal recessive condition, a child must inherit the mutation from both parents to be affected. The frequency of this variant varies significantly across different global populations, reflecting historical migration patterns and genetic ancestry. Understanding these frequency patterns is a key component of population genetics and helps clinicians assess the likelihood of carrier status in different ethnic groups.
Navigating Genetic Information
Accessing information about your genetic makeup can be empowering, but it is essential to interpret these results within a clinical context. Knowing that you carry the rs121912487 variant does not constitute a medical diagnosis, nor does it predict the severity of any potential health condition. Genetic testing results should always be reviewed with a qualified healthcare provider or a certified genetic counselor who can explain the implications of the findings based on your personal and family medical history. If you are concerned about cystic fibrosis or your carrier status, a clinician can provide appropriate screening and guidance. Avoid making health decisions based solely on raw genetic data, as clinical interpretation requires professional expertise to ensure accuracy and safety. Always prioritize discussions with your doctor regarding any concerns about your genetic health or potential risks.
How common is this variant?
The DeltaF508 mutation is most prevalent in populations of European descent, where approximately 2% of individuals are carriers.
Frequently asked questions
What does it mean to be a carrier of the DeltaF508 mutation?
Being a carrier means you have one copy of the mutated CFTR gene and one normal copy. Carriers typically do not show symptoms of cystic fibrosis but can pass the mutation to their children.
Can I be tested for the rs121912487 variant?
Yes, clinical genetic testing is available to identify the presence of the DeltaF508 mutation. You should speak with your primary care physician or a genetic counselor to determine if testing is appropriate for you.
Is the DeltaF508 mutation the only cause of cystic fibrosis?
No, cystic fibrosis can be caused by many different mutations in the CFTR gene. While DeltaF508 is the most common, there are hundreds of other known variants that can lead to the condition.
Does having the TT genotype guarantee I will have severe symptoms?
While the TT genotype is associated with cystic fibrosis, the severity of symptoms can vary significantly between individuals. Other genetic and environmental factors play a role in how the condition manifests.
Sources & further reading
Educational information only, last refreshed 10/8/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Severe pathogenic mutation (p.Gly542Ter) associated with cystic fibrosis.
Classic cystic fibrosis in-frame 3-bp deletion variant (p.Phe508del / deltaF508) causing misfolding and impaired chloride channel trafficking.
Pathogenic frameshift mutation (c.3659delC) in CFTR linked to cystic fibrosis.
Pathogenic nonsense variant (p.Gly542Ter / G542X) causing autosomal recessive cystic fibrosis when inherited in trans with another CFTR pathogenic allele.
Also known as p.Arg117His (R117H), this CFTR variant is associated with mild or atypical cystic fibrosis and congenital bilateral absence of the vas deferens, with clinical severity influenced by the poly-T tract background.
A CFTR mutation associated with cystic fibrosis and CFTR-related disorders.