The TMLHE gene helps the body make carnitine, a substance cells use to turn fat into energy. If it does not work well, the body may make less carnitine, which can affect energy use, especially during fasting or illness. Many variants in this gene have little effect, but some are linked to low carnitine levels and, in some people, developmental differences including autism spectrum features.
What is a gene?
Genes are stretches of DNA that carry instructions your cells use to make molecules or to manage processes throughout the body. Some genes provide the code for proteins, which are the parts of cells that do much of the work. Others are mainly involved in controlling when certain processes happen, where they happen, and how active they are. Taken together, genes affect how the body grows and works, and they can influence how you respond to food, stress, and medications. More detailed information on this topic is available in the LearnHub.
Overview
TMLHEGene function
What if the gene works
The TMLHE gene helps cells make carnitine, a substance that helps move fats into mitochondria, the parts of cells that make energy. This supports normal energy use, especially during times of higher demand.
Risk
What if the gene does not work
Changes in the TMLHE gene can reduce the body’s first step in making carnitine. Effects can range from no clear symptoms with milder or more severe variants to, in some males, a higher chance of autism or developmental differences.
Treatment
What does that mean for your treatment
No TMLHE-specific treatment or drug choice changes are currently established in clinical guidelines for pathogenic variants in the TMLHE gene. The TMLHE gene is being studied in carnitine metabolism, and L-carnitine supplementation has been explored in small studies, but it is not standard care.
Gene function
What if the gene works
Your cells use the TMLHE gene to begin making carnitine, a natural substance that helps move fat into mitochondria so it can be used for energy. This first step takes place inside mitochondria, the parts of cells that produce energy. When this pathway runs smoothly, it supports steady everyday fuel use.
One main role of the TMLHE gene is to carry out the first step in carnitine production. Its protein changes trimethyllysine (a small molecule released when proteins are recycled) into the next compound, so the rest of the pathway can continue.
By helping your body make carnitine, the TMLHE gene supports how cells use certain fats as fuel. Carnitine helps move long chain fats into mitochondria, where cells turn them into usable energy.
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, such as differences in appearance, metabolism, or the way the body responds to environmental influences. Many variants do not have any noticeable effect and simply represent natural genetic variation. In some cases, though, a variant can affect how a gene works more strongly and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the TMLHE gene can change how much enzyme the cell makes or how well that enzyme works, which is central to how TMLHE gene variants affect protein function. Milder variants may leave some activity intact, while more severe variants can shorten the protein, make it unstable, or stop it from working at all. This usually reduces the first step of carnitine production inside cells, though the functional impact can vary from one variant to another.
How variants are linked to conditions
TMLHE does not yet have a broadly confirmed link to a specific health condition, though research on TMLHE gene variants linked to conditions is still evolving. Anyone with a confirmed variant in the TMLHE gene should use their own test result together with advice from their doctor or genetic counselor, since interpretation depends on the exact change and the person’s clinical picture.
A variant is not necessarily a diagnosis
Genetic variants are a routine part of human biology and are widespread in the general population. Most do not have a direct effect on health and instead reflect natural variation among people. For many genes, carrying a variant associated with a condition suggests a possible link rather than a definite diagnosis, especially when more than one gene and environmental factors also contribute. In some situations, though, a single 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 clearly increase or reduce health risk related to the TMLHE gene. Some findings suggest risk may vary with the exact gene change and other genetic or environmental factors, but this is not settled; anyone concerned about personal risk should speak with a doctor or genetic counselor.
Inheritance of TMLHE variants
There is not yet a broadly confirmed Mendelian pattern for how TMLHE gene variants are inherited in relation to a specific, well-established TMLHE-related condition, because most reported changes have been studied as possible risk factors rather than clear single-gene causes. In practical terms, TMLHE gene inheritance still follows chromosome rules: the TMLHE gene is located on the X chromosome, so a child receives it from their mother if they are male, while females inherit one X-linked copy from each parent. This means inheritance can differ between sons and daughters.
What does my TMLHE result mean for my family?
There is not yet a broadly confirmed, condition-specific inheritance pattern for TMLHE that clearly predicts what a result means for relatives. Some TMLHE changes have been studied in relation to health and development, but their effect on family members is not always straightforward. If you have a specific TMLHE result, family implications are best interpreted in the context of that exact finding.
Genetic information
Genetic testing
How you find out about variants
Testing for variants in the TMLHE gene usually uses a blood, saliva, or cheek swab sample. In focused testing of the TMLHE gene, a lab reads the DNA code and looks for changes. Results may identify a benign variant, a pathogenic variant, or a variant of uncertain significance.
When should I consider getting a genetic test?
There is not yet a broadly established reason to test the TMLHE gene on its own. Decisions about genetic testing are usually based on the full picture, including symptoms, developmental history, and family history, with guidance from a doctor or genetic counselor.
A genetic result is only one part of your health story
A genetic result can provide useful insight, but how much it reveals depends on the condition and on the type of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, also shape how the body functions. For some conditions, especially those influenced by many genes, genetic information offers context rather than certainty and is best interpreted 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 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, has less effect in another, or causes more side effects in someone else. Part of the reason is that inherited differences can change how the body breaks down, transports, or responds to a drug, which is a common part of normal human variation.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences shape a person’s response to medications. It studies the relationship between genes and drugs to help explain why the same treatment may work differently from one person to another. For many medicines, genes affect both how strongly a drug works and how the body processes it. This information can support treatment decisions that are more informed and more individualized. You can learn more about this topic in the LearnHub.
Drugs influenced by the TMLHE gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medicine choices or dosing. If you have concerns about side effects, how well a treatment is working, or other health changes, it is best to discuss them with your doctor or pharmacist.
History
The TMLHE gene entered medical research through studies of rare inherited differences on the X chromosome and later gained wider attention in work on neurodevelopment. In recent decades, awareness of this gene’s role has grown as researchers looked more closely at families in which similar inherited patterns were seen. A notable step came in the early 2010s, when studies reported that loss of TMLHE activity appeared more often in some boys with autism than in comparison groups. From these first observations, research expanded steadily, and scientists recognized that the picture was more complex than early reports suggested. The way this gene was viewed has shifted over time, with newer studies placing it in a broader genetic and developmental context rather than treating it as a single clear explanation.