The DHH gene helps guide early development, especially the testes in a male fetus and the protective covering around some nerves. If it does not work properly, some people with XY chromosomes can be born with differences in sex development, and some may later develop nerve damage called neuropathy. These effects depend on the variant and whether one or both copies of the gene are affected.
What is a gene?
Genes are stretches of DNA that carry instructions your cells use to make molecules or regulate processes in the body. Some genes hold the information needed to produce proteins, the parts of cells that do the work. Others mainly control when certain processes happen, where they take place, and how strongly they run. Together, genes affect how the body develops and works, and they can also influence how you respond to food, stress, or medications. To go deeper into this topic, you can read more in the LearnHub.
Overview
DHHGene function
What if the gene works
The DHH gene helps guide early development of the testes and supports normal male sex development. It also helps form the protective coverings around peripheral nerves.
Risk
What if the gene does not work
Variants in the DHH gene can disrupt typical male sex development in some people with 46,XY chromosomes and may also affect peripheral nerves. Milder to more severe variants can lead to partial or complete gonadal dysgenesis, with variable nerve involvement.
Treatment
What does that mean for your treatment
No treatment or management approach specific to the DHH gene is currently established for pathogenic variants in the DHH gene. DHH signaling is being studied as a drug target and biomarker in some cancers and in developmental research, but this has not led to a guideline based therapy for people carrying a DHH variant.
Conditions associated with DHH
Gene function
What if the gene works
During early development, the DHH gene helps send short range messages between neighboring cells. These messages are especially important in the developing testes and in peripheral nerves, which are the nerves outside the brain and spinal cord. This explains the DHH gene's role in testis development and peripheral nerve support.
The DHH gene helps neighboring cells send and receive short range growth signals during development. This local communication helps tissues form in the right place and supports cells as they take on specialized roles.
Before birth, the DHH gene supports the organized development of the testes. It guides nearby support cells and hormone producing cells so testis tissue forms in a coordinated way.
In peripheral nerves, the DHH gene helps build protective outer layers around bundles of nerve fibers. These layers support a stable environment and help nerve signals travel along a well organized path.
What is a variant?
Within a gene, a genetic variant is a small change in the DNA sequence. These changes are common and help shape normal human diversity, including differences in appearance, metabolism, or the way the body responds to environmental influences. Many variants do not lead to any noticeable effect and simply represent natural genetic variation. In some situations, however, a variant can change how a gene works more substantially and may contribute to or directly cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the DHH gene can alter the protein's shape, reduce how much is made or sent out, or weaken this cell to cell signal. How DHH gene variants affect signaling depends on the change: milder variants may leave some activity, while more severe variants can greatly reduce or stop it. In people with two more disruptive variants, features linked to 46,XY differences in sex development often appear earlier or are more pronounced.
How variants are linked to conditions
Pathogenic variants in the DHH gene are a well-established cause of some forms of 46,XY differences of sex development, especially partial or complete gonadal dysgenesis. Among the conditions linked to DHH gene variants, the main ones affect genital development before birth and may also affect fertility later in life. Some people also develop a nerve condition that can cause numbness, weakness, or balance problems.
A variant is not necessarily a diagnosis
Genetic variants are a normal feature of human biology and are common in the general population. Most do not have a direct effect on health and simply reflect natural human diversity. For many genes, carrying a variant associated with a condition indicates a possible link rather than a definite diagnosis, especially when several genes and environmental factors are involved. 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?
There is not yet broadly confirmed evidence on specific factors that increase or reduce health risks related to the DHH gene itself. For many living with a DHH change, risk depends mainly on the exact variant and whether one or two copies are affected, so personal guidance from a doctor or genetic counselor can help put results in context.
Inheritance of DHH variants
DHH-related conditions are usually inherited in an autosomal recessive pattern. This means a person inherits one DHH gene variant from each parent, while parents who each carry one variant are often unaffected. For each pregnancy, two carrier parents have a 25% chance of having a child with the condition, a 50% chance of having a child who is a carrier, and a 25% chance of having a child with no familial variant. In practical terms, how variants of the DHH gene are inherited usually depends on both parents passing on a variant in the same gene.
What does my DHH result mean for my family?
For families with a disease-causing change in the DHH gene, this pattern is usually recessive, which means parents are often healthy carriers. Brothers and sisters may also have the same condition or be carriers, so the result can matter for siblings as well as future children in the family. More distant relatives may also carry the gene change without knowing it.
Genetic information
Genetic testing
How you find out about variants
Genetic testing for DHH variants usually uses a blood or saliva sample. A lab reads the DNA in the DHH gene to look for changes and may report a pathogenic variant, a benign variant, or a variant of uncertain significance. Testing may be done as a single-gene test or as part of a broader panel.
When should I consider getting a genetic test?
If a child with XY chromosomes has differences in sex development, such as atypical genital appearance, undescended testes, or delayed puberty, testing the DHH gene may help find a cause. It may also be considered when these features run in the family or occur along with nerve problems such as numbness or weakness.
A genetic result is only one part of your health story
A genetic finding can provide useful insight, but what it can tell you varies with the condition and the kind of variant present. How the body functions over time is also shaped by many other factors, including lifestyle, environment, age, and medical history. For some conditions, particularly those shaped by many genes, genetic information offers context rather than certainty and makes the most sense when considered alongside other parts of care. In other situations, a genetic finding can give a more definite answer. In areas like medication response, genetic results can also help put a person’s individual experience into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Small differences in genes can change how the body breaks down a drug, moves it through the bloodstream, or responds at the drug's target. Because of this, the same medication may work better for one person than another, or may be more likely to cause side effects in some people.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can shape a person’s response to medications. It studies connections between genes and drugs to help explain why the same treatment may work differently from one person to another. For many medicines, genes affect how strongly a drug works or how the body processes it. This understanding can support treatment decisions that are more informed and more individualized. More detail on this topic is available in the LearnHub.
Drugs influenced by the DHH gene
When should I seek medical advice?
There is no broadly confirmed role for this gene in guiding medication choices at this time, so questions about medicines, side effects, or treatment changes are best discussed with your doctor.
History
In the early 1990s, researchers identified the DHH gene as one of the human hedgehog genes, alongside SHH and IHH, after earlier work in fruit flies had revealed the broader hedgehog signaling family. This linked a well known developmental biology pathway to human genetics in a new way. Building on this early work, scientists mapped the DHH gene to chromosome 12 and began connecting rare inherited changes in it with differences in sex development and later with some nerve findings. Over time, descriptions became more precise as genetic testing improved. Although the DHH gene has stayed less publicly known than some other genes in the hedgehog family, its discovery helped expand understanding of how this important gene group relates to human health.