CFTR rs77010823: Understanding This Pathogenic Genetic Variant
The rs77010823 variant, also known as c.1585-1G>A or 1717-1G>A, is a pathogenic mutation located within the CFTR gene. It is associated with cystic fibrosis, a condition that occurs when an individual inherits this variant in combination with another pathogenic CFTR allele.
What each genotype means
Typical CFTR gene profile
This genotype represents the common, non-mutated state for this specific location in the CFTR gene. It does not carry the pathogenic splice-site mutation associated with cystic fibrosis risk at this position.
This is the most common genotype, found in the vast majority of the global population.
CFTR mutation carrier status
You carry one copy of the pathogenic c.1585-1G>A splice-site mutation. Being a carrier typically does not cause cystic fibrosis, but you should discuss this result with a genetic counselor or clinician to understand the implications for family planning and the potential for inheriting a second mutation in trans.
This genotype is rare, with the variant allele occurring at a global frequency of approximately 0.0002.
Potential cystic fibrosis risk
This genotype indicates the presence of two copies of the pathogenic c.1585-1G>A mutation. This mutation is known to disrupt normal mRNA splicing of the CFTR protein, which is associated with the development of cystic fibrosis; please consult with a medical specialist for clinical evaluation and management.
This genotype is extremely rare in the general population.
What is the rs77010823 Variant?
The rs77010823 variant is a specific change in the DNA sequence of the CFTR gene. In scientific literature, it is frequently referred to by its cDNA nomenclature, c.1585-1G>A, or historically as 1717-1G>A. This variant occurs at a critical location known as a canonical splice-site. Splice-sites are the boundaries between exons (coding regions) and introns (non-coding regions) in a gene. When the cellular machinery reads the gene to create a protein, it must precisely cut out the introns and join the exons together. Because this variant alters the G nucleotide at the -1 position of the splice acceptor site, it disrupts this process. Research indicates that this disruption leads to the skipping of exon 12 during transcription. This error introduces a frameshift, which creates a premature stop signal, ultimately preventing the cell from producing a stable, functional CFTR protein.
The Role of the CFTR Gene
The CFTR gene provides instructions for making the cystic fibrosis transmembrane conductance regulator protein. This protein functions as a channel across the membranes of cells that produce mucus, sweat, saliva, tears, and digestive enzymes. By transporting negatively charged particles called chloride ions into and out of cells, the CFTR protein helps control the movement of water in tissues, which is necessary for the production of thin, freely flowing mucus. When the CFTR gene is mutated, the resulting protein may be absent, non-functional, or produced in insufficient quantities. This leads to the production of thick, sticky mucus that can clog airways and ducts in the lungs, pancreas, and other organs. This physiological impairment is the hallmark of cystic fibrosis, a condition characterized by respiratory and digestive complications.
Research and Clinical Significance
The rs77010823 variant is classified as pathogenic, meaning it is well-documented in clinical research as a cause of disease. It has been identified in patients diagnosed with cystic fibrosis, particularly those presenting with classic symptoms such as elevated sweat chloride levels, pancreatic insufficiency, and an increased susceptibility to respiratory infections like Pseudomonas. The evidence for its pathogenicity is strong, supported by functional studies that confirm the variant causes aberrant transcription and a loss of protein function. It is important to note that cystic fibrosis is a recessive condition. This means that an individual typically only develops the disease if they inherit two pathogenic variants—one from each parent. If a person carries only one copy of this variant, they are considered a carrier and generally do not exhibit the symptoms of cystic fibrosis, though they may pass the variant to their children.
Population Frequency
The rs77010823 variant is considered rare in the general population. Data from the Genome Aggregation Database (gnomAD) indicates a global allele frequency of approximately 0.0002, or 0.02%. Some studies have reported slightly higher frequencies in specific cohorts of European descent, but it remains an uncommon finding in the general population. Because the variant is rare, the likelihood of an individual carrying it is low. However, genetic testing is often recommended for individuals with a family history of cystic fibrosis or for those undergoing routine carrier screening. Because this variant is associated with a serious health condition, clinical laboratories include it in standard panels designed to detect common and rare pathogenic CFTR mutations. If you have received a result indicating you carry this variant, it is recommended that you consult with a genetic counselor or your healthcare provider to understand the implications for your health and family planning.
What This Information Means for You
Understanding your genetic status regarding the CFTR gene is a personal health matter. If you have been identified as a carrier of rs77010823, it does not mean you have cystic fibrosis. However, it does mean that you have a 50% chance of passing this specific variant to your biological children. If your partner is also a carrier of a pathogenic CFTR variant, there is a risk that a child could inherit two pathogenic alleles, which could result in cystic fibrosis. This information is most useful for family planning and reproductive health discussions. It is important to remember that genetic testing results should always be interpreted by a qualified medical professional. Never use genetic data to make independent medical decisions or to diagnose yourself. If you have questions about your results, your risk, or potential testing for your partner, please speak with a clinical geneticist or a certified genetic counselor.
How common is this variant?
The rs77010823 variant is rare, with a global allele frequency of approximately 0.0002 in the gnomAD database.
Frequently asked questions
Is rs77010823 the same as 1717-1G>A?
Yes, rs77010823 and 1717-1G>A are different names for the same genetic variant. The rsID is the identifier used in modern databases, while the other name refers to the specific location of the mutation within the CFTR gene sequence.
Does having the rs77010823 variant mean I have cystic fibrosis?
No, being a carrier of one copy of this variant does not mean you have cystic fibrosis. Cystic fibrosis is a recessive condition, meaning it typically requires inheriting a pathogenic variant from both parents.
Should I get tested for CFTR mutations?
Carrier screening for CFTR mutations is often recommended for individuals with a family history of cystic fibrosis or those planning a pregnancy. You should discuss the benefits and limitations of genetic testing with your healthcare provider or a genetic counselor.
What should I do if I am a carrier of this variant?
If you are a carrier, it is recommended that you speak with a genetic counselor to understand the implications for your family. They can help explain the risks and discuss testing options for your partner.
Sources & further reading
Educational information only, last refreshed 10/14/2026. 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.