The HOXD13 gene helps guide how fingers and toes form before birth. This gene plays an important role in the early instructions that tell digits when to grow and separate. Pathogenic variants can cause hands or feet to develop differently, including fused, extra, or shorter fingers or toes. These changes often run in families, although the pattern and severity can vary from person to person.
What is a gene?
A gene is a stretch of DNA that carries instructions your cells use to make molecules or regulate processes in the body. Some genes hold the instructions for producing proteins, the parts that do the cell’s work. Others mainly guide when certain processes happen, where they take place, and how strongly they are carried out. Together, genes affect how the body grows and works, and they can 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
HOXD13Gene function
What if the gene works
The HOXD13 gene helps guide early development of the hands and feet, especially the growth and patterning of fingers and toes. It gives cells instructions that support normal limb formation before birth.
Risk
What if the gene does not work
Variants in the HOXD13 gene can disrupt hand and foot development, most often causing extra or fused fingers or toes, sometimes with shortened digits. Milder and more severe variants can influence which features appear and how noticeable they are.
Treatment
What does that mean for your treatment
No treatment or medication choice is currently guided specifically by pathogenic variants in the HOXD13 gene. Management is based on a person’s hand, foot, or limb findings and may include surgery, therapy, or supportive care rather than a treatment aimed at the HOXD13 gene.
Conditions associated with HOXD13
Gene function
What if the gene works
Early in development, your body uses the HOXD13 gene to help shape the ends of the arms and legs. Its instructions are especially important as hands, feet, fingers, and toes take form. Understanding how the HOXD13 gene works helps show how these parts grow in the right place and order.
The HOXD13 gene helps switch other genes on or off during early growth. Its protein attaches to DNA and guides a careful set of growth instructions.
During early growth, this gene helps organize the far end of the developing arms and legs. That is the area where hands, feet, fingers, and toes are laid out.
This gene supports the detailed shaping of fingers and toes as they form. This steady control helps explain how the HOXD13 gene shapes fingers and toes during early growth.
What is a variant?
A genetic variant is a slight difference in the DNA sequence within a gene. These differences are common and help shape normal human diversity, including traits such as appearance, metabolism, and the way the body responds to environmental influences. Many variants do not cause any noticeable effect and are simply part of natural genetic variation. In some cases, though, a variant can change how a gene works more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the HOXD13 gene can change the shape, stability, or DNA binding of the HOXD13 protein, which helps explain how HOXD13 gene variants affect hand and foot development. Some variants add extra alanine building blocks, making the protein clump inside cells, while others shorten it or weaken how strongly it binds DNA. Milder variants may leave some activity, but more severe variants can reduce it further and are often linked to more noticeable joined or extra fingers or toes.
How variants are linked to conditions
Pathogenic variants in the HOXD13 gene cause synpolydactyly, an inherited condition with fused fingers or toes and sometimes extra digits. Some HOXD13 variants are also linked to other inherited hand and foot differences, including certain forms of brachydactyly and syndactyly. HOXD13 gene variants linked to fused or extra fingers and toes can look quite different from one person to another, even within the same family.
A variant is not necessarily a diagnosis
Common and expected in human biology, genetic variants are found throughout the general population. Most have no direct effect on health and simply represent natural variation among people. In many genes, a variant tied to a condition suggests a possible association, not a certain diagnosis, particularly when multiple genes and environmental influences are involved. There are exceptions, however, where one well-characterized variant in a specific gene can by itself confirm a diagnosis.
Are there things that can increase or change my risk?
For HOXD13, risk is mainly shaped by whether a disease-causing gene change is inherited in the family. There is not enough evidence to say that lifestyle or environmental factors meaningfully increase or lower the chance of HOXD13-related hand or foot differences.
Inheritance of HOXD13 variants
HOXD13-related conditions are usually inherited in an autosomal dominant pattern, which means a child can inherit the altered copy from either parent. If a parent carries a disease-causing variant in the HOXD13 gene, each pregnancy has a 50% chance of passing it on. This is the key point when looking at how HOXD13 gene variants are inherited in families. Males and females can inherit and pass on these variants equally.
What does my HOXD13 result mean for my family?
A disease-causing change in the HOXD13 gene is usually passed down in a dominant pattern, so close relatives such as a parent, brother, sister, or child may also carry it and may have hand or foot differences, even if these are mild. In families with a known HOXD13-related condition, first-degree relatives are often the ones most likely to share the same result. Features can vary a lot from one family member to another.
Genetic information
Genetic testing
How you find out about variants
To find out whether you carry a change in the HOXD13 gene, doctors use genetic testing for HOXD13 variants, usually from a blood sample or cheek swab. A lab reads the gene's DNA code and checks for variants linked with inherited differences in hand or foot development. Results may show a disease-causing variant, a benign variant, or an unclear finding.
When should I consider getting a genetic test?
Genetic testing for the HOXD13 gene may be worth considering if you or your child has extra fingers or toes, fused digits, or other hand and foot differences, especially when these run in the family. A test can help confirm whether a change in HOXD13 is the cause and clarify the chance of it happening again in future children.
A genetic result is only one part of your health story
A genetic result can be helpful, but how much it explains depends on the condition and the type of variant involved. Many factors, including lifestyle, environment, age, and medical history, influence how the body functions over time. For some conditions, especially those shaped by many genes, genetic information offers context rather than certainty and is most useful when viewed alongside 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 personal experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how your body responds to medicines. Small differences in genes can change how a drug is absorbed, broken down, or moved through the body, so the same treatment may work better for one person than for another. These differences are common and can influence how much benefit a medicine gives or how sensitive someone is to side effects.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can shape a person’s response to medication. By looking at links between genes and drugs, it helps explain why the same treatment may work differently from one person to another. For many medicines, genes influence both how strongly a drug works and how the body processes it. This information can support more informed and individualized treatment decisions. To explore this topic further, you can learn more in the LearnHub.
Drugs influenced by the HOXD13 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choice or response, so general questions about medicines, side effects, or your health are best discussed with your doctor or pharmacist.
History
The HOXD13 gene entered medical genetics through families in which unusual hand and foot patterns clearly ran across generations. In the 1990s, researchers linked variants in the HOXD13 gene to synpolydactyly, a condition that can include extra fingers or toes together with joined digits. First described in the scientific literature as part of early genetics, this finding helped connect visible limb differences to specific developmental genes. From these first observations, research expanded steadily. Scientists then showed that different variants in the HOXD13 gene could be linked to a range of limb features, which sharpened genetic diagnosis and counseling. This work also helped establish homeobox genes as central players in human development.