The NDP gene gives instructions for a protein called norrin, which helps blood vessels grow normally in the retina and supports the inner ear. If this gene does not work properly, a person may be born with severe vision loss or blindness, and some later develop hearing loss. Some people with pathogenic variants in the NDP gene also have balance, learning, or developmental differences.
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 much of the work. Others mainly help determine when certain processes happen, where they take place, and how strongly they are carried out. Together, genes affect how the body develops and works, and they can influence how you respond to food, stress, or medications. For a more detailed look at this topic, you can visit the LearnHub.
Overview
NDPGene function
What if the gene works
The NDP gene helps guide blood vessel growth in the retina and supports normal eye development. Its protein also helps maintain parts of the inner ear needed for hearing and balance.
Risk
What if the gene does not work
Variants in the NDP gene can disrupt normal blood vessel growth in the retina, causing vision loss that ranges from mild retinal disease to blindness. Some people also develop hearing loss, and in more severe cases developmental or behavior changes.
Treatment
What does that mean for your treatment
At present, no NDP-specific treatment or drug-selection approach is established in clinical guidelines for people with a pathogenic variant in the NDP gene. The NDP gene is being studied in early retinal gene therapy and norrin-pathway research aimed at supporting normal blood vessel growth in the eye.
Conditions associated with NDP
Gene function
What if the gene works
Your eyes and inner ears depend on the NDP gene for clear signals during development and routine tissue care. It helps nearby cells organize tiny blood vessels, a key part of how the NDP gene helps the retina develop and stay nourished. These signals also support a stable vessel lining so fluid stays where it belongs.
The NDP gene makes a protein called norrin that carries messages between nearby cells. These messages turn on cell programs that guide growth, connection, and orderly tissue building.
In the eye, norrin helps form the retina's blood vessels in an orderly pattern. This supports oxygen and nutrient delivery across the light sensing tissue that makes vision possible.
Norrin helps blood vessels develop a tight lining called the blood retina barrier, which limits unwanted leakage. This keeps the retinal environment steadier for normal visual function.
In the inner ear, the same signal supports tiny blood vessels that nourish hearing structures. This helps keep the local fluid and energy balance needed for hearing.
What is a variant?
A genetic variant is a minor change in the DNA sequence within a gene. These changes are common and help shape normal human diversity, including differences in appearance, metabolism, or the way the body reacts to environmental influences. Many have no noticeable effect and are simply part of natural genetic variation. In some situations, though, a variant can change how a gene works to a greater extent and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
In discussions of how variants influence the NDP gene's function, most pathogenic changes reduce the amount of working norrin protein or weaken how it binds nearby cell partners. Some variants mainly alter the protein's shape or release from the cell, while more severe variants can stop it from being made at all. This loss of signaling can range from partial to near complete, which often tracks with milder or earlier, more extensive eye findings.
How variants are linked to conditions
Pathogenic variants in the NDP gene cause Norrie disease, an X-linked condition that often leads to severe vision loss from birth or early infancy and may also include hearing loss or developmental differences in some people. Other NDP gene variants are linked to familial exudative vitreoretinopathy, another inherited retinal condition with a wide range of severity. These NDP gene variants linked to eye conditions do not all have the same effect, so findings can differ from one family to another.
A variant is not necessarily a diagnosis
Gene variants are a usual feature of human biology and are widely found across the population. Most do not directly affect health and instead reflect normal human variation. For many genes, having a variant associated with a condition points to a possible link, not a certain diagnosis, particularly when several genes and environmental influences play a role. Still, in some situations, one well-defined variant in a particular gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
For NDP, risk is mostly shaped by family inheritance rather than lifestyle. A child’s chance of being affected depends mainly on whether the altered NDP gene is passed down, and boys are usually much more strongly affected than girls. There is not enough evidence to say that diet, exercise, or other everyday habits change this genetic risk.
Inheritance of NDP variants
For families learning how NDP gene variants are inherited, the main pattern is X linked recessive. The NDP gene sits on the X chromosome, so mothers who carry a disease causing variant can pass it to sons and daughters, while fathers pass their X chromosome only to daughters. A carrier mother has a 50% chance in each pregnancy of passing the variant on; sons who inherit it are more likely to be affected, and daughters who inherit it are usually carriers, though some may have features. An affected father passes the variant to all daughters and to none of his sons.
What does my NDP result mean for my family?
For NDP, family implications are usually linked to an X-linked pattern. This can mean boys and men in the family are more likely to have serious eye problems, while girls and women may be carriers and can sometimes have milder eye changes. If a child has a disease-causing NDP result, close relatives on the mother’s side may also want to learn whether they carry the same change.
Genetic information
Genetic testing
How you find out about variants
Testing for variants in the NDP gene usually uses a blood or saliva sample. NDP genetic testing reads the gene’s DNA to look for sequence changes and sometimes missing or extra pieces, which can help confirm an inherited eye condition and clarify whether relatives may also carry the same variant.
When should I consider getting a genetic test?
Consider NDP genetic testing if a baby or child has severe vision loss from birth or early infancy, especially in boys, or if there is a family history of Norrie disease or related eye conditions. Testing can help confirm the cause and clarify whether other relatives may also carry the change.
A genetic result is only one part of your health story
A genetic result can be informative, but how much it can explain varies with the condition and the kind of variant involved. Over time, many factors shape how the body works, including lifestyle, environment, age, and medical history. For some conditions, especially those influenced by many genes, genetic information provides context rather than certainty and is best understood along with other parts of care. In other situations, a genetic result may give a clear answer. In areas like medication response, genetic findings 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. This helps explain why the same treatment works well for one person, seems less helpful for another, or causes more side effects in someone else. Differences in how the body absorbs, breaks down, transports, or responds to a drug are common, and they can influence both benefit and sensitivity to treatment.
What is Pharmacogenetics?
Pharmacogenetics looks at how genetic differences shape a person’s response to medication. It examines connections between genes and drugs to help explain why the same treatment can work differently from one person to the next. For many medicines, genes influence both how strongly a drug works and how the body processes it. This information can support more informed and more individualized treatment decisions. You can read more about this topic in the LearnHub.
Drugs influenced by the NDP gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication response, so any concerns about medicines, side effects, or changes in your health are best discussed with your doctor.
History
Norrie disease was described clinically in the 1920s, long before its genetic cause was known. Initially understood only through visible traits, later recognized as tied to a specific gene, the NDP gene became a focus once researchers mapped the condition to the X chromosome. In the early 1990s, scientists identified variants in the NDP gene in families affected by this inherited eye condition. From these first observations, research expanded steadily, linking the gene to a broader range of eye findings in some people and families. These historical steps shaped today’s understanding of Norrie disease and related inherited retinal conditions.