ABO rs1264301: Genetic Variation and Vascular Biomarkers
The genetic variant rs1264301 is a common single nucleotide polymorphism located in the ABO gene region on chromosome 9. Genome-wide association studies have identified statistical links between this variant and circulating levels of vascular adhesion molecules like sICAM-1, as well as baseline venous thromboembolism risk. Because rs1264301 acts within a complex set of blood group haplotypes, its direct clinical effect size remains modest and limited.
What each genotype means
| Genotype | What the research suggests | Reading |
|---|---|---|
| Major Allele Homozygote (e.g., C/C) | This genotype represents the baseline reference background at rs1264301. It is typically associated with average population levels of soluble ICAM-1 and standard baseline vascular risk. It carries no significant independent risk on its own. | Informational |
| Heterozygote (e.g., C/T) | Carriers of one copy of the variant allele display intermediate statistical associations with circulating adhesion molecules. In population studies, this corresponds to modest baseline shifts in vascular biomarker levels. It does not represent an actionable medical condition. | Informational |
| Minor Allele Homozygote (e.g., T/T) | Individuals with two copies of the minor allele reflect genetic patterns seen in specific ABO haplotypes linked to higher sICAM-1 and slightly elevated statistical VTE susceptibility. The clinical effect size is small and must be considered alongside overall cardiovascular health. It does not warrant clinical interventions in the absence of other risk factors. | Higher attention |
Understanding rs1264301 and Genomic Location
The single nucleotide polymorphism rs1264301 is located on chromosome 9 (9q34.2) within the ABO gene region. Genetic variations in this chromosomal locus involve single base substitutions that either sit in noncoding regulatory regions or travel closely in linkage disequilibrium with primary coding variants defining the ABO histo-blood group. Rather than causing a distinct genetic disorder, rs1264301 represents normal, inherited variation that tags functional haplotypes across the ABO gene cluster. Because many polymorphisms in this region segregate together, identifying an association with rs1264301 frequently reflects broader genetic patterns that influence both ABO transferase expression and related biological pathways.
The Biological Role of the ABO Gene
The ABO gene encodes glycosyltransferase enzymes responsible for transferring specific carbohydrate molecules onto precursor antigens, establishing the human ABO blood group system (A, B, AB, and O). Beyond decorating red blood cell membranes, these carbohydrate antigens are expressed on endothelial cells, platelets, and various plasma proteins. Key vascular proteins, including von Willebrand factor and coagulation factor VIII, carry ABO glycan chains that directly alter their plasma half-life and clearance rates. Additionally, ABO-mediated glycosylation influences cell surface receptors and endothelial activation markers, providing a biochemical bridge linking the ABO locus to circulatory physiology and inflammatory signaling.
Research Evidence on sICAM-1 and Thrombosis
Large-scale genome-wide association studies have robustly linked genetic variation at the ABO locus to circulating levels of cell adhesion molecules, particularly soluble intercellular adhesion molecule-1 (sICAM-1), as well as soluble P-selectin and E-selectin. Population research demonstrates that alleles tagging non-O blood groups generally correlate with altered biomarker concentrations and a higher relative baseline risk of venous thromboembolism (VTE). However, evidence linking rs1264301 specifically to clinical outcomes remains categorized as limited to moderate. The variant's statistical association is primarily driven by its correlation with the broader ABO blood group background, which exerts a modest, polygenic influence on thrombosis susceptibility rather than acting as a strong, independent risk factor.
Population Frequency and Allelic Variation
The minor allele for rs1264301 exhibits a frequency generally ranging between 0.20 and 0.30 across global populations in public databases such as gnomAD and the 1000 Genomes Project. While common in European, East Asian, and American ancestral cohorts, subtle frequency shifts occur across geographic ancestries in tandem with worldwide distributions of ABO blood group alleles. Homozygous individuals for either allele, as well as heterozygotes, are widely represented in the general population. Because these alleles are common and naturally occurring, carrying any specific genotype at rs1264301 does not imply a clinical abnormality or an inherent disease state.
Interpreting Results in Everyday Health
Genotype findings for rs1264301 provide insight into statistical associations observed across large cohorts, but they cannot diagnose a medical condition or predict whether an individual will develop a blood clot. Multifactorial traits like venous thromboembolism depend far more heavily on major clinical risk factors—such as prolonged immobility, major surgery, active cancer, smoking, and age—than on any single noncoding ABO variant. Commercial consumers should never alter prescription medications, such as anticoagulants or cardiovascular therapies, based on genetic consumer tests. Any concerns regarding personal or familial thrombosis risk should be evaluated by a healthcare professional using comprehensive clinical assessments.
How common is this variant?
The minor allele frequency for rs1264301 is approximately 0.20 to 0.30 across major global ancestral groups, making both heterozygous and homozygous genotypes commonly observed worldwide.
Frequently asked questions
Can rs1264301 tell me my exact ABO blood type?
Not reliably on its own. While rs1264301 is located within the ABO gene region and correlates with specific blood group haplotypes, standard serological testing or full ABO exon sequencing is necessary to determine clinical blood type.
Does having a risk allele mean I will develop a blood clot?
No. The variant is only statistically associated with small changes in baseline population risk for venous thromboembolism. Clotting risk is overwhelmingly determined by clinical factors such as surgery, immobility, pregnancy, and smoking.
What is sICAM-1 and why does ABO affect it?
Soluble ICAM-1 is an adhesion molecule released into the bloodstream that is involved in cellular migration and vascular inflammation. The ABO gene encodes glycosyltransferases that alter the glycosylation and biological clearance of many vascular proteins, influencing their circulating levels.
Should I change any medications based on my rs1264301 result?
No, you should never stop, start, or alter any medication based on rs1264301. If you are taking anticoagulant therapies or have a personal history of blood clots, discuss your medical management directly with your physician.
Sources & further reading
Educational information only, last refreshed 9/6/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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