The SELENOI gene helps your cells make phosphatidylethanolamine, a key membrane fat used throughout the body, including the brain and nerves. When both copies do not work properly, cells may have trouble building and maintaining these membranes, which can cause a rare inherited condition linked to developmental delay, movement stiffness or weakness, seizures, and sometimes hearing or vision problems. In medicine, this gene is important because it supports normal nervous system development.
What is a gene?
Genes are stretches of DNA that give your cells instructions for making molecules or regulating processes in the body. Some genes carry the code for proteins, which do much of the cell’s work. Others mainly direct when certain processes happen, where they take place, and how active they are. Taken together, genes affect how the body develops and works, and they can influence how you respond to food, stress, or medications. If you want to go into this topic in more detail, you can read more in the LearnHub.
Overview
SELENOIGene function
What if the gene works
The SELENOI gene helps cells make a key membrane fat called phosphatidylethanolamine. This supports membrane structure and cell signaling, especially in the brain and nervous system.
Risk
What if the gene does not work
Variants in the SELENOI gene can lead to an inherited condition that affects movement and development. Milder to more severe variants may cause a range of findings, often including leg stiffness or weakness, delayed development, and seizures.
Treatment
What does that mean for your treatment
No SELENOI-specific treatment or management approach is currently established.
Conditions associated with SELENOI
Gene function
What if the gene works
Cell membranes need the right mix of fats to stay flexible and organized. One important part of that mix is phosphatidylethanolamine, which cells make with help from the SELENOI gene. This is a central part of what the SELENOI gene does in the body and supports everyday cell function.
The SELENOI gene helps cells make phosphatidylethanolamine, one of the main fats in cell membranes. This step gives cells fresh material to build and renew their outer lining and internal membranes.
It also helps produce a slightly different chemical form of this membrane fat that many tissues use. These fats add to the membrane mix cells rely on for steady day to day function.
By supplying these membrane fats, SELENOI supports membrane shape and the small membrane compartments cells use to sort and move materials. This helps routine tasks such as growth, transport, and turnover run smoothly.
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 variation in appearance, metabolism, and the way the body responds to environmental influences. Many have no noticeable effect and are simply part of natural genetic variation. In some situations, however, a variant changes how a gene functions more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the SELENOI gene can change the shape or stability of this cell membrane enzyme, so it works less well or not at all. In many descriptions of how SELENOI gene variants affect protein function, the main result is reduced production of phosphatidylethanolamine, an important membrane fat, which can disrupt membrane balance inside cells. Milder variants may leave some activity, while more severe variants can nearly abolish activity and often have a larger biological effect.
How variants are linked to conditions
A well-established link connects the SELENOI gene to hereditary spastic paraplegia type 81 (SPG81). This rare inherited condition can cause increasing leg stiffness and weakness, trouble walking, delayed development, and speech or learning difficulties. In affected families, the diagnosis is typically confirmed when a person has disease-causing variants in both copies of the SELENOI gene.
A variant is not necessarily a diagnosis
Genetic variants are common across the general population and are a normal part of human biology. Most do not directly affect health and simply reflect natural human diversity. For many genes, having a variant associated with a condition points to a possible link rather than a clear diagnosis, particularly when several genes and environmental factors play a role. In some situations, though, one well-characterized variant in a particular 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 risk related to the SELENOI gene. For families with a known SELENOI change, risk is mainly shaped by whether that gene change is inherited, and a doctor or genetic counselor can help explain what that means for you or your relatives.
Inheritance of SELENOI variants
The way SELENOI gene variants are inherited is typically autosomal recessive. This means a child usually inherits one altered copy of the SELENOI gene from each parent. Parents with one altered copy are usually carriers, and with each pregnancy they have a 25% chance of having an affected child, a 50% chance of having a carrier child, and a 25% chance of having a child without the familial variant. Boys and girls are affected equally because the SELENOI gene is on an autosome, not a sex chromosome.
What does my SELENOI result mean for my family?
For SELENOI, the best-known related condition follows a recessive inheritance pattern. In practical terms, close relatives may be carriers even if they do not have symptoms, and brothers or sisters could also be affected if they inherited the same gene change from both parents. This usually matters most for siblings and for relatives planning children.
Genetic information
Genetic testing
How you find out about variants
To look for changes linked to the SELENOI gene, doctors use genetic testing for SELENOI variants, usually on a blood or saliva sample. A lab reads the DNA code to check for variants in the SELENOI gene and reports whether a finding may help explain a person’s condition or support family testing.
When should I consider getting a genetic test?
Testing for the SELENOI gene may be considered when a child has unexplained developmental delay along with muscle stiffness or weakness, movement problems, or changes on brain scans that suggest an inherited nerve condition. It can also help when these features run in the family, especially if affected relatives are siblings.
A genetic result is only one part of your health story
A genetic finding can provide valuable insight, but the amount it reveals varies with the condition and the kind of variant involved. How the body functions over time is also shaped by many factors, including lifestyle, environment, age, and medical history. For some conditions, particularly those affected by many genes, genetic information offers context rather than certainty and is most useful when viewed together with other parts of care. In other situations, a genetic result can give a clear answer. In areas like medication response, genetic results may help put a person’s 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 absorbs, breaks down, transports, or responds to a drug. This is common and helps explain why the same treatment works well for one person, works less well for another, or causes more side effects in someone else.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences affect the way people respond to medications. It focuses on links between genes and drugs to help explain why the same treatment can work differently from one person to another. For many medicines, genes influence how strongly a drug works or how the body handles it. This information can support more informed, more individualized treatment decisions. More on this topic is available in the LearnHub.
Drugs influenced by the SELENOI 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 how well they work, so any concerns about side effects, new symptoms, or treatment changes are best discussed with your doctor.
History
SELENOI was first studied under the name EPT1, based on the enzyme activity researchers could measure in cells before the gene itself was fully characterized. As genetics and protein studies improved, scientists recognized that this gene belongs to the human selenoprotein family, which led to the name SELENOI. Scientific classifications changed as researchers learned more about the gene. That renaming marked an important step because it linked older biochemical findings with newer genetic research. Over time, work on SELENOI also became more clinically relevant as rare inherited changes in this gene were connected with human neurologic conditions.