CD33 rs12459419: What Your Genotype Means
The rs12459419 variant is a single nucleotide polymorphism located in the CD33 gene that influences how the cell processes mRNA. This genetic change is associated with altered risk for Alzheimer's disease and has been studied for its potential impact on the efficacy of specific targeted therapies in acute myeloid leukemia.
What each genotype means
Higher full-length CD33 expression
This genotype is associated with higher levels of full-length CD33 protein on the surface of immune cells. Research suggests this configuration may be linked to a higher risk of Alzheimer's disease compared to those carrying the T allele, and some studies have investigated whether it influences clinical outcomes in AML patients treated with gemtuzumab-ozogamicin. Please discuss any concerns regarding medication response or disease risk with your clinician.
This is a common genotype, observed in approximately 44% to 50% of individuals in certain studied cohorts.
Intermediate CD33 expression
This genotype results in a mix of full-length and truncated CD33 protein expression due to the influence of the T allele on mRNA splicing. Each copy of the T allele is associated with a reduction in full-length CD33 and a decrease in Alzheimer's disease risk odds. If you are undergoing treatment for AML, please consult your pharmacist or physician regarding how this genetic profile may relate to your specific therapy.
This heterozygous genotype is frequently observed, appearing in roughly 50% of participants in some clinical studies.
Lower full-length CD33 expression
This genotype is associated with the highest proportion of truncated CD33 protein and the lowest levels of full-length CD33. This variant is linked to a reduced risk of Alzheimer's disease in population studies. Because this genetic profile may influence how your immune cells function or respond to certain therapies, please discuss your clinical history and any relevant medications with your healthcare provider.
This is the least common genotype for this variant, found in approximately 5% to 6% of individuals in studied cohorts.
Understanding the rs12459419 Variant
The rs12459419 variant is a genetic change located within exon 2 of the CD33 gene. In genetics, a single nucleotide polymorphism (SNP) represents a variation at a single position in the DNA sequence. This specific variant is located in a splice enhancer region, which acts as a set of instructions for the cell to correctly assemble the final mRNA transcript. When this sequence is altered, it can change how the gene's instructions are read, leading to the production of different versions, or isoforms, of the CD33 protein. Because this variant sits in a critical regulatory region, it has been the subject of extensive research regarding its functional impact on protein structure and cellular behavior.
The Role of the CD33 Gene
The CD33 gene provides instructions for making a protein that is primarily found on the surface of immune cells, such as microglia in the brain and myeloid cells in the blood. CD33 functions as a receptor that helps regulate immune responses. In the context of Alzheimer's disease, CD33 is involved in the activity of microglia, which are the brain's resident immune cells responsible for clearing debris, including amyloid-beta plaques. The rs12459419 variant influences the production of a truncated isoform of the CD33 protein that lacks a specific domain known as the IgV domain. Research suggests that this truncated version may alter the ability of microglia to clear amyloid-beta, which is why this variant is frequently investigated in studies of Alzheimer's disease risk.
Research and Clinical Associations
Research has established a link between the rs12459419 variant and a reduced risk of developing Alzheimer's disease. The mechanism is thought to involve the increased expression of the truncated CD33 isoform, which may enhance the clearance of amyloid-beta by microglia. In the field of pharmacogenomics, this variant has also been studied in patients with acute myeloid leukemia (AML) who are treated with gemtuzumab-ozogamicin, a drug that targets the CD33 protein. Because the variant affects the presence of the drug-binding site on the CD33 protein, researchers hypothesized it might influence treatment response. However, evidence remains mixed; while some studies suggest it is a predictive factor in specific patient subsets, other research has found no significant association with clinical outcomes like survival in broader adult AML cohorts. Evidence for these associations is considered moderate, and findings often vary based on the specific patient population studied.
Interpreting Your Genetic Information
It is important to understand that genetic variants like rs12459419 represent only one piece of a complex biological puzzle. While scientific studies identify statistical associations between this variant and health outcomes, these findings do not predict an individual's personal health destiny. Factors such as environment, lifestyle, and other genetic markers play significant roles in both Alzheimer's disease risk and responses to medical treatments. If you are concerned about how this variant might relate to a specific medication or a health condition, you should discuss this information with your clinician or pharmacist. They can provide context based on your full medical history and current clinical guidelines. Never use genetic information to make independent decisions about your healthcare or medication dosing.
How common is this variant?
The frequency of the rs12459419 variant varies significantly by ancestry, with the T allele being more prevalent in European populations compared to others. In European cohorts, genotype frequencies are approximately 46.9% for C/C, 44.1% for C/T, and 8.9% for T/T.
Frequently asked questions
Is rs12459419 a diagnostic test for Alzheimer's disease?
No, rs12459419 is not a diagnostic test. While it is associated with a change in Alzheimer's disease risk, it is not a definitive predictor of whether an individual will develop the condition.
Does my CD33 genotype mean I will not respond to leukemia treatment?
Not necessarily. While the variant affects the structure of the CD33 protein, studies on its impact on drug response in AML have shown mixed results. You should consult your oncologist to understand how your specific treatment plan is tailored to your needs.
Can I change my CD33 genotype?
No, your genotype is determined at conception and cannot be changed. Genetic variants are inherited from your parents and remain constant throughout your life.
Where can I find more information about my genetic results?
You should discuss any genetic reports with a qualified healthcare provider or a genetic counselor. They can help interpret the results in the context of your overall health and medical history.
Sources & further reading
Educational information only, last refreshed 9/22/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant influences the splicing of CD33 and is associated with the efficacy of gemtuzumab ozogamicin therapy in acute myeloid leukemia.
This variant in the CD33 gene is associated with altered CD33 protein expression and efficacy of the leukemia drug gemtuzumab ozogamicin.
This variant influences CD33 expression and splicing in microglia, modulating the risk of developing Alzheimer's disease.