The THPO gene gives your body instructions to make thrombopoietin, a signal that helps the bone marrow produce platelets, the blood cells that help stop bleeding. This gene helps your body maintain healthy platelet levels and support early blood-forming cells. If the THPO gene does not work properly, platelet counts may become too low, which can lead to easy bruising, nosebleeds, or heavy periods, and some people may also develop bone marrow failure. Certain variants can instead raise platelet counts above the usual range.
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 directions for making proteins, the parts of cells that do the work. Other genes are mainly involved in controlling when certain processes happen, where they happen, and how active they are. Together, genes affect how the body develops and functions, and they can also shape how you respond to food, stress, or medicines. To go deeper into this topic, you can find more in the LearnHub.
Overview
THPOGene function
What if the gene works
The THPO gene helps your body make thrombopoietin, a hormone that tells bone marrow cells to produce platelets. It also supports stem cells that make blood cells, helping keep blood production steady.
Risk
What if the gene does not work
Changes in the THPO gene can upset platelet production, causing either too few platelets with bleeding and sometimes bone marrow failure, or too many platelets with clotting risk. Milder and more severe variants can differ in timing and severity.
Treatment
What does that mean for your treatment
For people with a pathogenic variant in the THPO gene, treatment can differ from other inherited low-platelet conditions. Thrombopoietin receptor agonists such as romiplostim or eltrombopag may improve platelet production and can be used as targeted therapy, while stem cell transplant is usually not the first option.
Conditions associated with THPO
Gene function
What if the gene works
The THPO gene helps control how your body makes platelets, the tiny blood cells that help stop bleeding after a cut. Its protein, thrombopoietin, acts as a steady signal to the bone marrow, where new blood cells are made. It also supports early blood-forming stem cells so blood production stays balanced over time.
The THPO gene sends a key signal that helps bone marrow cells develop into megakaryocytes, the large cells that release platelets. This is a central part of what the THPO gene does in the body.
THPO also helps blood-forming stem cells stay healthy and ready to renew themselves. This supports steady blood cell production over time.
Thrombopoietin levels are shaped by ongoing contact with platelets and their precursor cells in the bone marrow. This feedback system helps keep platelet production within a healthy range.
What is a variant?
A genetic variant is a minor change in the DNA sequence within a gene. These changes are common and are part of normal human diversity, including differences in appearance, metabolism, and the way the body responds to environmental factors. Many variants do not have any noticeable effect and simply represent natural genetic variation. In some situations, though, a variant can change how a gene works more significantly and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Changes in the THPO gene can reduce how much thrombopoietin is made, make the protein unstable, or weaken its binding to the MPL receptor (the cell's docking site), which shows how variants in the THPO gene affect its function. Some variants are milder and leave partial activity, while more severe variants may leave little or no active signal. Rare control region variants can instead raise protein production, which may influence how early or how strongly blood count changes appear.
How variants are linked to conditions
Variants in the THPO gene are linked to inherited platelet disorders. Certain variants in the THPO gene can cause hereditary thrombocythemia, a condition with persistently high platelet counts. Other, more disruptive variants in both copies of the THPO gene can cause thrombocytopenia that may be severe and can occur with bone marrow failure or aplastic anemia.
A variant is not necessarily a diagnosis
Genetic variants are a common, normal part of human biology. Most do not directly affect health and instead reflect natural variation among people. For many genes, having a variant associated with a condition points to a possible link rather than a confirmed diagnosis, particularly when several genes and environmental influences also play a role. Still, there are situations in which one well-characterized variant in a particular gene is enough to confirm the diagnosis.
Are there things that can increase or change my risk?
There is not yet broadly confirmed evidence on specific factors that increase or reduce health risks linked to THPO changes. Risk often depends most on the exact gene change and the condition involved, so anyone concerned about personal or family risk should speak with a doctor or genetic counselor.
Inheritance of THPO variants
How THPO gene variants are inherited depends on the specific THPO related condition. Some THPO variants follow an autosomal dominant pattern, which means a parent carrying the variant can pass it to a child with a 50% chance in each pregnancy. Other THPO related conditions are autosomal recessive, meaning a child inherits one altered copy from each parent, while the parents are usually healthy carriers. Because of this, inheritance of THPO gene variants is not described by one single pattern for every family.
What does my THPO result mean for my family?
THPO results can have different meanings for family members because this gene is linked to more than one inherited platelet condition. In some families, a changed THPO copy can be passed from an affected parent, so close relatives may also carry the same result and may have high platelet counts. In other families, the condition appears only when both parents are carriers, which can matter for siblings and future children.
Genetic information
Genetic testing
How you find out about variants
If low platelet counts run in your family, THPO genetic testing for inherited low platelet counts can look for variants in the THPO gene using a blood or saliva sample. A lab reads the gene’s DNA code and compares it with the usual sequence to see whether a variant may help explain the platelet pattern.
When should I consider getting a genetic test?
Consider THPO testing if there is lifelong unexplained low platelet counts, bone marrow failure, or a family history of inherited very high platelet counts. Testing can help show whether a change in the THPO gene is the cause and whether it may run in the family.
A genetic result is only one part of your health story
A genetic result can provide useful insight, but how much it explains varies by the condition and the kind of variant involved. Over time, many factors also affect how the body functions, including lifestyle, environment, age, and medical history. For some conditions, especially those shaped by many genes, genetic information offers context rather than certainty and is best interpreted along with other parts of care. In other situations, a genetic result may give a clear answer. In areas like medication response, genetic results can also help put individual experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Small differences in DNA can change how the body breaks down a drug, moves it through the body, or responds to it at its target. Because of this, the same medication may work well for one person, do little for another, or cause more side effects in someone who is more sensitive to it. These differences are common and are one reason treatment response can vary from person to person.
What is Pharmacogenetics?
Pharmacogenetics focuses on how genetic differences affect the way people respond to medicines. It examines links between genes and drugs to help explain why the same treatment can work differently from one person to another. For many medications, genes influence both how strongly a drug works and how the body handles it. Understanding this can support treatment decisions that are more informed and more personalized. More detailed information on this topic is available in the LearnHub.
Drugs influenced by the THPO gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding how medicines are chosen or used, so any questions about medications, side effects, or new symptoms are best discussed with your doctor.
History
For decades, researchers suspected the body made a signal that controlled platelet production, but its identity remained unclear. In 1994, several research teams independently identified this factor and linked it to the THPO gene, a major step in blood cell research. It was also recognized as the natural partner for MPL, a cell surface receptor already known from earlier studies. Building on this early work, scientists connected THPO gene variants with rare inherited conditions affecting platelet counts. That discovery helped turn an old biological question into a clearer genetic story and shaped later research on bone marrow health and blood disorders.