What you carry at this position in your DNA and what research says about it.
Cystic Fibrosis Risk: 10/10 evidence, 12 publications.
You're viewing every possible genotype for this variant.
None of these is your result. Use the genotype toggle to compare them, then sign up and upload your DNA to see which one is yours.
Sample genotype (not yours): G/G
Typical Cystic Fibrosis Risk
Two copies of the typical G allele mean normal CFTR protein function. There is no elevated genetic risk for cystic fibrosis or related conditions from this marker.
What this genotype means: Typical CFTR channel function; No elevated risk of cystic fibrosis.
Sample genotype (not yours): A/A
High Cystic Fibrosis Risk
Two copies of the A allele cause cystic fibrosis. This genotype is highly responsive to targeted ivacaftor therapy.
What this genotype means: Cystic fibrosis diagnosis; Responsive to ivacaftor therapy.
Sample genotype (not yours): G/A
Cystic Fibrosis Carrier
One copy of the A allele indicates carrier status for cystic fibrosis. It also elevates the risk for hereditary pancreatitis.
What this genotype means: Carrier of cystic fibrosis; Increased risk of hereditary pancreatitis.
Gene function and biological role
Gene Function: The CFTR gene encodes a membrane protein that functions as a regulated chloride channel across epithelial cells [1]. This channel is crucial for maintaining the balance of salt and water on many surfaces, such as in the lungs and pancreas [1]. When the channel is defective, mucus becomes thick and sticky, clogging airways and ducts [2]. Mutations in this gene can lead to cystic fibrosis, a progressive multi-organ disease [2]. It also plays a role in male fertility and pancreatic health [3].
Variant Impact: The rs75527207 variant, commonly known as G551D, represents a missense mutation in the CFTR gene [4]. This specific change alters the glycine residue at position 551 to aspartate, disrupting the channel's ability to open and close properly [5]. Unlike mutations that cause protein misfolding, this is classified as a gating defect where the channel reaches the cell surface but remains closed [5]. It is a rare variant globally, found primarily in populations of European descent [6]. Because of its unique gating mechanism, it responds to specific potentiator medications designed to force the channel open [1].
Key Insight: Unlike most cystic fibrosis mutations that prevent the protein from reaching the cell surface, G551D creates channels that reach the surface but cannot open.
Location: CFTR. Chromosome 7 · 7q31.2 · 117.6 Mb
Estimated prevalence by population
Global 99.9%; European 99.9%; African 100.0%; East Asian 100.0%; South Asian 100.0%; Americas 100.0%; Ashkenazi 100.0%; Finnish 100.0%; Middle Eastern 100.0%; Amish 100.0%.
Estimated GG genotype frequency.
Global 0.1%; European 0.1%; African 0.0%; East Asian 0.0%; South Asian 0.0%; Americas 0.0%; Ashkenazi 0.0%; 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 0.0%; 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 23974870. Typical Risk.
Ivacaftor Response. Evidence: 10/10. Source: PMID 22047557. Typical Response.
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.
Showing effects for A/A genotype
Cystic Fibrosis. Evidence: 10/10. Source: PMID 23974870. High Risk.
Ivacaftor Response. Evidence: 10/10. Source: PMID 22047557. Responsive.
Hereditary Pancreatitis. Evidence: 10/10. Source: PMID 23974870. Increased 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 23974870. Carrier Status.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Normal CFTR protein function is expected with two copies of the typical G allele. There is no elevated genetic risk for cystic fibrosis or related conditions like hereditary pancreatitis from this specific marker [1]. The chloride channels on epithelial cell surfaces open and close normally, maintaining healthy mucus consistency in the respiratory and digestive tracts [2]. Because there is no gating defect present, there is no clinical indication for CFTR potentiator therapies like ivacaftor [3]. Most people worldwide carry this typical genotype [4]. It represents the baseline health status for this locus.
Typical CFTR channel function; No elevated risk of cystic fibrosis.
Sample genotype: AA (Homozygous)
Two copies of the A allele result in cystic fibrosis, a serious genetic condition [1]. This genotype causes severe dysfunction in chloride transport, leading to thick mucus buildup in the lungs and pancreas [2]. It is associated with progressive pulmonary disease and pancreatic exocrine insufficiency [3]. However, because G551D is a gating mutation, these channels are present on the cell surface but fail to open [4]. This makes this genotype highly responsive to the targeted drug ivacaftor, which directly binds to and opens the channel [5]. Clinical trials have shown that this treatment significantly improves lung function and weight gain [5].
Cystic fibrosis diagnosis; Responsive to ivacaftor therapy.
Sample genotype: GA (Heterozygous)
A single copy of the A allele designates carrier status for cystic fibrosis [1]. While carriers typically do not develop full cystic fibrosis, they can pass the variant to their offspring [1]. There is, however, an increased risk for hereditary pancreatitis, which can manifest even with a single copy of the variant [2]. In some cases, carriers may also experience mild respiratory symptoms or localized issues if they carry a second, different CFTR mutation on the other chromosome [3]. If cystic fibrosis is present due to a second mutation, the G551D variant makes the patient eligible for ivacaftor therapy [4]. This medication helps open the defective chloride channels to improve lung function [4].
Carrier of cystic fibrosis; Increased risk of hereditary 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 CFTR potentiator in patients with cystic fibrosis and the G551D mutation.
Effect of genotype on phenotype and mortality in cystic fibrosis: a retrospective cohort study.
Effect of VX-770 in persons with cystic fibrosis and the G551D-CFTR mutation.
Correlation between genotype and phenotype in patients with cystic fibrosis.
Content updated August 2026.
ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.
Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026
Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com