FUT2 rs602662: What Your Genotype Means
The rs602662 variant is a genetic change in the FUT2 gene that influences how your body secretes blood group antigens and processes vitamin B12. It is a key marker used by researchers to understand individual differences in gut health, nutrient absorption, and immune responses.
What each genotype means
Secretor status
This genotype is associated with the 'secretor' phenotype, meaning you express ABO blood group antigens in your saliva and other bodily fluids. Research indicates this status may influence susceptibility to certain gastrointestinal infections, such as specific strains of norovirus.
Carried by approximately 80% of the population, though frequencies vary significantly by ancestry.
Secretor status
Because the secretor trait is dominant, carrying one copy of the functional allele typically results in the 'secretor' phenotype. You express ABO blood group antigens in your secretions, which may affect your interaction with certain pathogens compared to non-secretors.
This heterozygous genotype is common in many populations, reflecting the widespread distribution of the secretor trait.
Non-secretor status
This genotype is associated with the 'non-secretor' phenotype, meaning you do not express ABO blood group antigens in your saliva or gastrointestinal mucosa. Research has linked this status to altered susceptibility to certain infections and variations in plasma vitamin B12 levels; some studies also suggest an association with lower BMI and different metabolic profiles.
Carried by approximately 20% of individuals of European ancestry, though this frequency varies widely across different global populations.
Understanding the rs602662 Variant
The rs602662 variant is a single nucleotide polymorphism (SNP) located within the FUT2 gene on chromosome 19. In genetics, a SNP represents a variation at a single position in the DNA sequence. Specifically, rs602662 involves a change where a glycine amino acid is replaced by a serine at position 258 of the FUT2 protein. This specific change is highly correlated with other well-known variants in the same gene, such as rs601338, which is the primary determinant of 'secretor' status. Because these variants are often inherited together, rs602662 serves as a reliable proxy for identifying whether an individual is a secretor or a non-secretor. While it sits in a region of the genome associated with various metabolic and immune traits, it is most frequently studied for its functional impact on the enzyme's ability to modify proteins and cell surfaces.
The Role of the FUT2 Gene
The FUT2 gene provides instructions for making an enzyme called alpha-(1,2)-fucosyltransferase. This enzyme is responsible for adding fucose sugar molecules to glycan chains on the surface of cells and on secreted proteins. These modified proteins, known as histo-blood group antigens, are found in bodily fluids like saliva and in the lining of the digestive tract. By creating these antigens, the FUT2 enzyme helps shape the chemical environment of the gut. Furthermore, this enzyme modifies haptocorrin, a protein that binds to vitamin B12 in the blood. Because of this, the activity of the FUT2 enzyme directly influences how the body metabolizes and circulates vitamin B12. When the FUT2 gene is less active, as seen in non-secretors, the glycosylation of these proteins is altered, which can lead to measurable differences in both gut microbiota composition and circulating nutrient levels.
Research Associations and Evidence
Research has established strong associations between FUT2 variants and several biological traits. The most prominent is 'secretor status,' which determines if an individual secretes ABO blood group antigens into their secretions. Non-secretors, who lack this ability, have shown resistance to certain gastrointestinal infections, such as specific strains of norovirus, because these viruses often use these antigens to attach to host cells. Conversely, the variant has been linked to susceptibility to other pathogens, including certain bacteria. Beyond immunity, rs602662 is recognized as one of the strongest genetic determinants of circulating vitamin B12 levels. Studies have also explored its potential link to metabolic profiles and conditions like Crohn's disease, though the mechanisms remain complex. It is important to note that while these statistical associations are strong in research cohorts, they do not predict individual health outcomes or diagnose specific medical conditions.
Population Frequency
The frequency of the rs602662 variant varies significantly across different ancestral populations. In many European populations, approximately 20% of individuals are classified as non-secretors, a phenotype strongly linked to the presence of specific alleles at this locus. However, the genetic architecture of secretor status is not uniform globally. For instance, other variants like rs1047781 are more common in East Asian populations as a cause of the non-secretor phenotype, making rs602662 less informative in those groups. Because of this, researchers emphasize that the utility of any single SNP depends heavily on the genetic background of the population being studied. Understanding these ancestral differences is crucial for interpreting genetic data accurately and avoiding generalizations that may not apply to all individuals.
What This Information Means for You
Knowing your genotype for rs602662 provides insight into your biological predispositions, such as your secretor status or potential tendencies regarding vitamin B12 levels. However, it is vital to understand that genetics is only one piece of the puzzle. Environmental factors, diet, and lifestyle play significant roles in your overall health. You cannot use this information to diagnose yourself with a condition or to determine your immunity to any specific virus. If you are concerned about your vitamin B12 levels or gut health, the most appropriate step is to consult with a healthcare professional or a registered dietitian. They can order clinical blood tests to assess your actual nutrient status and provide guidance based on your unique health history. Never use genetic information to make changes to your medication or supplement regimen without first discussing it with your doctor or pharmacist.
How common is this variant?
Approximately 20% of individuals of European descent are non-secretors, though the specific alleles responsible for this status vary significantly across global populations.
Frequently asked questions
What does it mean to be a 'secretor'?
Being a secretor means your body produces and releases ABO blood group antigens into your saliva, mucus, and other bodily fluids. This process is controlled by the FUT2 gene, which modifies proteins on your cell surfaces.
Can this variant predict if I will get the flu?
No, this variant does not predict your susceptibility to the seasonal flu. It is primarily associated with resistance or susceptibility to specific gastrointestinal viruses like norovirus, not respiratory influenza.
Does my rs602662 result mean I have a vitamin B12 deficiency?
Not necessarily. While this variant is associated with differences in circulating vitamin B12 levels, it does not mean you are deficient. Only a clinical blood test ordered by your doctor can determine your actual vitamin B12 status.
Should I change my diet based on my FUT2 genotype?
There is no standard medical recommendation to change your diet based solely on this SNP. If you have concerns about your nutrition or gut health, consult a healthcare provider or dietitian for personalized advice.
Sources & further reading
Educational information only, last refreshed 10/2/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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FUT2 non-secretor variant influencing the gut microbiome diversity and serum vitamin B12 absorption and levels.
Intronic non-secretor haplotype marker contributing to Lewis and ABH histo-blood group antigen presence in saliva and body fluids.
Determines secretor status — whether blood-group antigens appear in body fluids — and influences norovirus susceptibility.