The CD33 gene gives immune cells instructions for a surface protein that helps control how strongly they react, especially in blood forming cells and the brain’s immune cells. This gene plays an important role in keeping immune signaling balanced, and if it does not work as expected, cells may clear debris less well or send less controlled signals. Some variants in the CD33 gene are linked to differences in Alzheimer’s disease risk, and CD33 is also a treatment target in some leukemias, including acute myeloid leukemia.
What is a gene?
Genes are sections of DNA that carry instructions your cells use to make molecules or regulate processes in the body. Some genes provide the instructions for making proteins, which are the parts of cells that do much of the work. Others mainly help control when certain processes happen, where they take place, and how strongly they occur. As a group, genes affect how the body develops and works, and they can also influence how you respond to food, stress, or medications. For a more detailed look at this topic, you can find more in the LearnHub.
Overview
CD33Gene function
What if the gene works
The CD33 gene helps control activity in certain white blood cells. Its protein sits on the cell surface and tones down immune signals. This helps keep immune responses measured and supports how these cells handle material around them.
Risk
What if the gene does not work
Milder to more severe variants in the CD33 gene can change how much CD33 protein reaches the cell surface or how well it sends signals. This can alter how certain immune cells recognize and respond to surrounding material.
Treatment
What does that mean for your treatment
No CD33-specific treatment or management approach is currently established for people with a pathogenic or loss-of-function variant in the CD33 gene. CD33 is being used and studied as a drug target in acute myeloid leukemia, where therapies such as gemtuzumab ozogamicin target CD33 on leukemia cells rather than inherited CD33 variants.
Gene function
What if the gene works
Your immune cells need the CD33 gene for calm, controlled communication as they patrol the body. It helps certain white blood cells recognize common sugar patterns on cell surfaces and adjust how strongly they respond. This helps explain the CD33 gene’s role in immune cells, especially cells involved in routine tissue cleanup.
The CD33 gene helps certain immune cells recognize sialic acids, which are common sugar tags on cell surfaces. This lets those cells read their surroundings and respond in a more informed way.
When CD33 is active at the cell surface, it sends signals that soften immune activation. This helps certain white blood cells stay measured during routine tissue patrol and everyday cleanup.
CD33 also influences how some immune cells take in nearby material, including worn out cell pieces. That supports steady housekeeping in tissues and more controlled processing of what the cells encounter.
What is a variant?
A genetic variant is a small difference in the DNA sequence within a gene. These differences are common and help shape normal human diversity, including variation in appearance, metabolism, or the way the body responds to environmental influences. Many variants do not have any noticeable effect and are simply part of natural genetic variation. In some cases, though, a variant can change how a gene functions more significantly and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
CD33 gene variants can change how much CD33 protein reaches the cell surface or which version of the protein a cell makes. Some variants alter splicing (the way cells edit RNA instructions), so exon 2 is skipped and a shorter protein is produced without an important binding region. Milder variants may partly reduce protein stability or signaling, while more disruptive variants can greatly lower full-length CD33 or stop protein production altogether. These changes mainly affect protein structure, abundance, and cell-to-cell interactions.
How variants are linked to conditions
Common variants in the CD33 gene are most clearly linked to late-onset Alzheimer disease. In population studies, the main CD33 gene and Alzheimer's disease risk finding is that some versions are associated with a slightly higher chance of developing the condition, while others are linked to a lower chance. These associations affect risk trends across groups of people and do not by themselves confirm or rule out a diagnosis.
A variant is not necessarily a diagnosis
Genetic variants are a usual part of human biology and are widely seen in the general population. Most do not directly affect health and instead reflect natural human diversity. For many genes, having a variant associated with a condition suggests a possible link rather than a confirmed diagnosis, especially when multiple genes and environmental factors also play a role. In some situations, though, a single well-characterized variant in a specific gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
Some CD33 gene changes are linked with a small shift in the chance of developing late-onset Alzheimer’s disease, but they do not act alone. Overall risk is also shaped by age, family history, other genes such as APOE, and common brain and heart health factors like smoking, high blood pressure, diabetes, and low physical activity.
Inheritance of CD33 variants
There is not yet a broadly confirmed Mendelian pattern for how CD33 gene variants are inherited in relation to a specific CD33 related condition, although research continues to develop. For most people asking how CD33 gene variants are inherited, the key point is that CD33 is mainly studied as a risk influencing gene rather than one with a single well established dominant or recessive pattern. The CD33 gene is located on chromosome 19, which is an autosome, so you inherit one copy from each parent.
What does my CD33 result mean for my family?
There isn't yet a broadly confirmed inheritance pattern tied to a specific inherited condition for CD33. Changes linked to CD33 are usually discussed as small shifts in risk, not a clear-cut inherited condition that would let you predict who in a family will be affected. If you have a specific CD33 result and questions about relatives, a doctor or genetic counselor can help explain what it may mean in your family.
Genetic information
Genetic testing
How you find out about variants
A lab can look for changes in the CD33 gene using a blood sample or cheek swab. If you are looking into CD33 genetic testing, the test reads the gene’s DNA code and checks for specific variants or broader sequence changes. Results may show whether a variant is present, absent, or of uncertain significance.
When should I consider getting a genetic test?
There isn’t yet a widely accepted, CD33-specific reason for genetic testing in routine care. Decisions about testing are usually based on your personal or family history and are best discussed with a doctor or genetic counselor, especially in the setting of memory problems or research studies.
A genetic result is only one part of your health story
A genetic result can provide useful insight, but how much it explains depends on the condition and on the kind of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, affect how the body functions. For some conditions, particularly those shaped by many genes, genetic information offers context rather than certainty and makes the most sense when considered with other parts of care. In other situations, a genetic result can give a clear answer. In areas like medication response, genetic results can also help put individual experiences in context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. This helps explain why the same treatment works well for one person, has little effect in another, or causes more side effects in someone else. Small differences in genes can change how the body breaks down a drug, moves it through the body, or reacts to it at its target, which can influence both benefit and sensitivity.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in a person’s genes affect the way they respond to medicines. By studying links between genes and drugs, it helps explain why the same treatment may not work in the same way for everyone. For many medicines, genes can influence both how powerfully a drug works and how the body handles it. This information can support treatment choices that are better informed and more personalized. More detailed information on this topic is available in the LearnHub.
Drugs influenced by the CD33 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choices, so general questions about side effects, treatment response, or medicine safety are best discussed with your doctor. Research on CD33 has looked at whether certain genetic changes may affect response to some leukemia treatments that attach to CD33, but this has not become routine prescribing guidance.
History
In recent decades, awareness of this gene’s role has grown. CD33 was first identified in the 1980s as a marker on myeloid blood cells, which helped doctors sort different kinds of leukemia more accurately. From these first observations, research expanded steadily. CD33 later became important in cancer care because it was used to guide diagnosis and became a target for antibody based treatment in acute myeloid leukemia. Interest in CD33 widened again when genetic studies linked some variants near the CD33 gene to differences in Alzheimer’s disease risk. These milestones made CD33 part of both blood cancer research and the growing search for genetic factors involved in brain aging.