CFTR rs121918361: Understanding This Rare Genetic Variant
The rs121918361 variant is a rare genetic change located within the CFTR gene. It has been identified in research as a potential contributor to atypical or mild cystic fibrosis phenotypes when present in specific genetic combinations.
What each genotype means
Typical CFTR function
This genotype represents the common, expected sequence at this position in the CFTR gene. It is not associated with the atypical or mild cystic fibrosis phenotypes linked to the variant allele.
This is the most common genotype observed across all global populations.
Potential atypical CFTR carrier
Carrying one copy of this variant may be associated with atypical or mild cystic fibrosis-related symptoms, though evidence remains limited. Because CFTR-related conditions are complex and influenced by other genetic and environmental factors, you should discuss these findings with a genetic counselor or clinician to understand their relevance to your health.
This genotype is rare and its frequency varies significantly depending on ancestral background.
Atypical CFTR variant state
This genotype involves two copies of the variant, which has been highlighted in research for its potential to cause atypical or mild cystic fibrosis phenotypes. Clinical expression can be highly variable, and this result should be interpreted by a medical professional in the context of your personal and family health history.
This genotype is extremely rare in the general population.
What is the rs121918361 Variant?
The rs121918361 variant is a single nucleotide polymorphism (SNP) found within the CFTR gene. In genetics, a SNP represents a variation at a single position in the DNA sequence. This specific variant is categorized as rare, meaning it is not commonly found in the general population. Because the CFTR gene is large and complex, researchers track thousands of different variants to understand how they influence protein function. When a variant like rs121918361 is identified, scientists look at its location within the gene to predict whether it might alter the structure or production of the resulting protein. This variant is currently studied for its potential role in influencing the severity of CFTR-related conditions, though its exact impact can vary depending on the presence of other genetic factors.
The Role of the CFTR Gene
The CFTR gene provides instructions for creating the cystic fibrosis transmembrane conductance regulator protein. This protein acts as a channel that transports negatively charged particles called chloride ions into and out of cells. This movement is essential for maintaining the proper balance of salt and water on cell surfaces, which helps keep mucus thin and free-flowing in organs like the lungs, pancreas, and digestive tract. When the CFTR gene contains pathogenic variants, the channel may not function correctly or may be absent entirely. This leads to the production of thick, sticky mucus that can obstruct airways and ducts. Understanding how specific variants like rs121918361 affect this channel is a major focus of ongoing research, as it helps clinicians better understand why some individuals experience mild symptoms while others face more severe health challenges.
Research and Clinical Evidence
Evidence regarding rs121918361 is currently limited. In the context of genetic research, 'limited' means that while the variant has been observed in individuals with atypical or mild cystic fibrosis symptoms, there is not yet enough large-scale data to definitively categorize its clinical impact for every individual. Some variants in the CFTR gene are known to cause classic cystic fibrosis, while others are associated with 'CFTR-related disorders'—conditions that may affect only one organ system or present with milder symptoms. Because this variant is rare, it is often studied in the context of 'compound heterozygosity,' where an individual carries one variant on one chromosome and a different variant on the other. Researchers emphasize that the clinical outcome is often determined by the combined effect of both variants, rather than the presence of a single SNP alone.
Population Frequency
The rs121918361 variant is considered rare, and its frequency varies significantly across different ethnic and ancestral populations. In many large-scale genomic databases, such as gnomAD, this variant appears at an extremely low frequency or is absent entirely in many cohorts. Because it is so rare, it is difficult to establish a precise percentage of how often it appears in the general population. Geneticists often find that rare variants are more common in specific geographic or ancestral groups due to historical population patterns. If you have received information about this variant, it is important to recognize that its rarity means that population-wide statistics may not accurately reflect your personal genetic background or health risks.
What This Information Means for You
If you have identified this variant in your genetic data, it is essential to approach the information with caution. Genetic variants in the CFTR gene do not automatically result in a diagnosis of cystic fibrosis. Many people carry rare variants without experiencing any health issues, especially if they do not have a second, more severe variant on their other chromosome. This information is for educational purposes and should not be used to make medical decisions. If you are concerned about your genetic health or family history, the most appropriate step is to consult with a certified genetic counselor or a medical professional. They can help interpret your results in the context of your overall health, family history, and clinical symptoms, and can guide you on whether further diagnostic testing is necessary.
How common is this variant?
The rs121918361 variant is rare, with frequency estimates varying significantly by ethnicity and ancestral background.
Frequently asked questions
Does having the rs121918361 variant mean I have cystic fibrosis?
No, having this variant does not mean you have cystic fibrosis. Cystic fibrosis is a complex condition, and the presence of a single rare variant is not sufficient for a diagnosis.
What should I do if I find this variant in my DNA report?
You should discuss the finding with a healthcare provider or a genetic counselor. They can help you understand the clinical relevance of the variant based on your personal and family health history.
Why is this variant called 'rare'?
A variant is called rare when it is found in a very small percentage of the general population. Most people do not carry this specific genetic change.
Can I use this information to choose a medication?
No. You should never use genetic information to start, stop, or change any medication. Always consult your clinician or pharmacist regarding any treatment decisions.
Sources & further reading
Educational information only, last refreshed 10/6/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant is a pathogenic insertion (c.1153_1154insAT) in the CFTR gene associated with cystic fibrosis.
This variant (p.Arg117His) is a well-documented pathogenic mutation associated with CFTR-related disorders, including atypical cystic fibrosis and congenital bilateral absence of the vas deferens, with severity modulated by the poly-T tract.
This variant is associated with cystic fibrosis, affecting chloride channel function in epithelial cells.
The most common mutation (DeltaF508) causing Cystic Fibrosis.
A "gating" mutation in Cystic Fibrosis that responds to specific modulators.
This variant is a known mutation associated with cystic fibrosis clinical presentation.