What you carry at this position in your DNA and what research says about it.
Cystic Fibrosis Risk: 10/10 evidence, 8 publications.
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Sample genotype (not yours): G/G
Typical Cystic Fibrosis Risk
Two copies of the typical gene sequence are present. There is no elevated risk of cystic fibrosis or related conditions from this specific genetic marker.
What this genotype means: Normal CFTR protein production; Typical risk of cystic fibrosis; Typical male fertility.
Sample genotype (not yours): A/A
High Risk of Cystic Fibrosis
Two copies of the severe splice mutation are present. This genotype is strongly associated with classic cystic fibrosis and related systemic complications.
What this genotype means: Severe CFTR protein deficiency; High risk of cystic fibrosis; Male infertility.
Sample genotype (not yours): G/A
Cystic Fibrosis Carrier
One copy of the severe splice mutation is present. While generally healthy, there is a risk of passing this variant to offspring and a slightly higher risk of pancreatitis.
What this genotype means: Reduced CFTR channel activity; Risk of passing variant to offspring; Increased risk of pancreatitis.
Gene function and biological role
Gene Function: The CFTR gene encodes the cystic fibrosis transmembrane conductance regulator, a specialized protein channel that transports negatively charged chloride and bicarbonate ions across cellular membranes [1]. This transport process is critical for maintaining the proper balance of salt and water on epithelial surfaces, such as those lining the lungs, pancreas, and digestive tract [1]. When CFTR function is disrupted, secretions become abnormally thick and sticky, leading to organ damage and chronic infections [2]. Beyond classic cystic fibrosis, milder variations in this gene are linked to localized conditions like male infertility and chronic pancreatitis [3].
Variant Impact: This specific variant, known historically as 1717-1G->A, alters a highly conserved splice acceptor site at the junction of intron 11 and exon 12 in the CFTR gene [2]. This single-nucleotide substitution disrupts the normal splicing machinery, preventing the correct assembly of the mature messenger RNA [2] [4]. Consequently, the cell cannot produce functional CFTR protein from this template, resulting in a complete loss of chloride channel activity [4]. Because it leads to a non-functional protein, this variant is classified as a severe, disease-causing mutation when inherited alongside another CFTR mutation [3].
Key Insight: While cystic fibrosis is a recessive condition, carriers of a single copy of this variant still face an increased risk of developing chronic pancreatitis.
Location: CFTR. Chromosome 7 · 7q31.2 · 117.6 Mb
Origin Story: This ancient variant is estimated to have originated approximately 10,600 years ago in European populations.
Estimated prevalence by population
More than 99.9% of people in every population we have data for carry the GG genotype, so this position varies very little between people.
Global < 0.1%; European < 0.1%; African 0.0%; East Asian 0.0%; South Asian 0.0%; Americas 0.0%; Ashkenazi 0.1%; Finnish 0.0%; Middle Eastern 0.0%; Amish 0.0%.
Estimated GA genotype frequency.
Global < 0.1%; European < 0.1%; African 0.0%; East Asian 0.0%; South Asian 0.0%; Americas 0.0%; Ashkenazi < 0.1%; Finnish 0.0%; Middle Eastern 0.0%; Amish 0.0%.
Estimated AA genotype frequency.
Showing effects for G/G genotype
Rare Genetic Disorders
Cystic Fibrosis & Ion Channel Disorders
Cystic Fibrosis. Evidence: 10/10. Source: PMID 2210769. Typical Risk.
Inherited Metabolic Disorders
Hereditary Pancreatitis. Evidence: 10/10. Source: PMID 23974870. Typical Risk.
Endocrine & Reproductive
Male Reproductive Health & Fertility
Male Infertility. Evidence: 10/10. Source: PMID 23974870. Typical Risk.
Organ Systems
Respiratory Health
Bronchiectasis. Evidence: 10/10. Source: PMID 23974870. Typical Risk.
Immunity & Inflammation
Inflammatory & Circulating Protein Markers
Soluble TREM2 Levels. Evidence: 4/10. Source: PMID 31708768. Associated.
Showing effects for A/A genotype
Cystic Fibrosis. Evidence: 10/10. Source: PMID 2210769. High Risk.
Hereditary Pancreatitis. Evidence: 10/10. Source: PMID 23974870. High Risk.
Male Infertility. Evidence: 10/10. Source: PMID 23974870. High Risk.
Bronchiectasis. Evidence: 10/10. Source: PMID 23974870. High Risk.
Showing effects for G/A genotype
Cystic Fibrosis. Evidence: 10/10. Source: PMID 2210769. Carrier.
Hereditary Pancreatitis. Evidence: 10/10. Source: PMID 23974870. Increased Risk.
Male Infertility. Evidence: 10/10. Source: PMID 23974870. Carrier.
Bronchiectasis. Evidence: 10/10. Source: PMID 23974870. Carrier.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Having two copies of the typical G allele means the cellular machinery can correctly splice and assemble the CFTR protein [1]. This ensures normal chloride and bicarbonate transport across epithelial membranes, keeping mucus thin and organs functioning properly [1]. There is no increased risk of developing cystic fibrosis, hereditary pancreatitis, or congenital male infertility from this specific locus [2]. While this result is highly reassuring, it does not rule out being a carrier for other, rarer CFTR mutations not covered by this specific test [3]. Maintaining general respiratory and digestive health remains the standard recommendation.
Normal CFTR protein production; Typical risk of cystic fibrosis; Typical male fertility.
Sample genotype: AA (Homozygous)
Inheriting two copies of the 1717-1G->A mutation results in a complete absence of functional CFTR chloride channels [1]. This severe defect causes thick, sticky mucus to accumulate in the lungs, pancreas, and other organs, leading to the classic symptoms of cystic fibrosis [1] [2]. Common complications include recurrent respiratory infections, progressive lung damage, and pancreatic insufficiency requiring enzyme replacement [2]. In males, this genotype also causes congenital bilateral absence of the vas deferens, resulting in infertility [3]. Modern medical management and targeted therapies can significantly improve quality of life and outcomes.
Severe CFTR protein deficiency; High risk of cystic fibrosis; Male infertility.
Sample genotype: GA (Heterozygous)
Carrying one copy of the 1717-1G->A mutation means about half of the CFTR proteins produced are non-functional due to splicing errors [1]. Although the remaining functional channels are usually sufficient to prevent cystic fibrosis, carriers have a significantly higher risk of developing hereditary pancreatitis [2]. There is also a 50% chance of passing this mutation to children, making partner screening important for family planning [3]. If both parents are carriers, each child has a 25% chance of inheriting cystic fibrosis [3]. Some carriers may also experience mild respiratory symptoms under specific environmental stressors.
Reduced CFTR channel activity; Risk of passing variant to offspring; Increased risk of pancreatitis.
Variants with shared genetic architecture
rs113993958 · CFTR Gene · Chr 7 · Cystic Fibrosis Risk
rs113993959 · CFTR Gene · Chr 7 · Cystic Fibrosis Risk
rs121908757 · CFTR Gene · Chr 7 · Cystic Fibrosis Risk
A 3' splice site consensus sequence mutation in the cystic fibrosis gene.
A cystic fibrosis patient with the nonsense mutation G542X and the splice site mutation 1717-1.
Content updated August 2026.
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