The GLDC gene makes a protein that helps break down glycine, a natural substance your body uses every day. This gene plays an important role in keeping glycine levels balanced, especially in the brain. If the GLDC gene does not work properly, glycine can build up and cause a condition called nonketotic hyperglycinemia, which may lead to seizures, low muscle tone, feeding problems, and developmental delay. This condition often starts in infancy, although milder forms can appear later.
What is a gene?
Genes are sections of DNA that carry instructions cells use to make molecules or guide processes throughout the body. Some genes provide the code for proteins, which do much of the cell’s work. Others mainly regulate when certain processes happen, where they happen, and how active they are. As a group, genes affect how the body grows and works, and they can also influence how you respond to food, stress, and medications. To go deeper into this subject, you can find more in LearnHub.
Overview
GLDCGene function
What if the gene works
The GLDC gene helps cells break down glycine, a building block of proteins. This supports normal energy use and keeps glycine from building up, especially in the brain.
Risk
What if the gene does not work
Variants in the GLDC gene can cause nonketotic hyperglycinemia, a condition in which glycine builds up and affects the brain. Effects range from severe newborn seizures and low muscle tone to milder later onset learning, movement, or behavior problems.
Treatment
What does that mean for your treatment
Pathogenic variants in the GLDC gene are usually managed with sodium benzoate to lower glycine levels and medicines such as dextromethorphan to reduce glycine's effects in the brain. Some clinicians also try pyridoxine, since a small number of people may improve. Treatment is individualized and supportive, and no current therapy corrects the underlying GLDC change.
Conditions associated with GLDC
Gene function
What if the gene works
Every day, your cells process glycine, a natural amino acid from food and normal body activity, with help from the GLDC gene. Inside mitochondria, this gene helps turn glycine into smaller parts the body can reuse. This is part of how the GLDC gene helps break down glycine in the body. That supports steady cell chemistry and the making of key cell building blocks.
The GLDC gene helps your cells break down glycine, a common amino acid. This step happens inside mitochondria, the parts of cells that carry out much of their energy work.
As glycine is processed, the GLDC gene helps produce a small carbon unit that folate can carry. Your cells reuse these carbon pieces to make DNA and other important molecules.
By moving glycine through this pathway, the GLDC gene supports a steady balance of small chemicals inside cells. This helps routine metabolism stay organized from moment to moment.
What is a variant?
A genetic variant is a small difference in the DNA sequence within a gene. These differences are common and help shape normal human diversity, such as variation in appearance, metabolism, or how the body responds to environmental influences. Many have no noticeable effect and are simply part of natural genetic variation. In some cases, though, a variant can more substantially change how a gene functions and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Many variants in the GLDC gene change the shape or stability of its protein, so cells break down glycine less well. In plain terms, this is how GLDC gene variants affect protein function. Milder variants may leave some activity, while more severe variants can greatly reduce enzyme activity or stop the protein from joining its partner proteins. In nonketotic hyperglycinemia, lower remaining activity often goes with earlier and more marked symptoms.
How variants are linked to conditions
Disease-causing variants in the GLDC gene cause glycine encephalopathy, also called nonketotic hyperglycinemia. This GLDC gene condition often starts in newborns with sleepiness, poor feeding, low muscle tone, breathing problems, or seizures, while some people have later and milder forms with developmental delay, learning difficulties, or movement problems. Finding disease-causing variants in both copies of the GLDC gene can confirm the diagnosis.
A variant is not necessarily a diagnosis
Genetic variants are a routine part of human biology and are common across 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 several genes and environmental factors also play a role. 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?
For GLDC, risk is mainly shaped by genetics rather than lifestyle. A child is at risk for this condition when they inherit two nonworking GLDC copies, so family history and parents who are blood relatives can raise the chance. There is not enough evidence to say that diet, exercise, or other everyday habits lower this genetic risk.
Inheritance of GLDC variants
Inheritance of the GLDC gene variants linked to disease is usually autosomal recessive. This means a person typically inherits one changed copy of the GLDC gene from each parent. Parents who each carry one variant usually do not have the condition themselves, but with each pregnancy there is a 25% chance their child will inherit both variants and have GLDC-related nonketotic hyperglycinemia, a 50% chance the child will be a carrier, and a 25% chance the child will inherit neither variant.
What does my GLDC result mean for my family?
For families with a disease-causing GLDC result, it usually means both parents are healthy carriers. Brothers and sisters may also be affected or may be carriers, and other close relatives could be carriers too. This can matter for future pregnancies and family planning, so relatives may wish to consider carrier testing if the family variant is known.
Genetic information
Genetic testing
How you find out about variants
To find variants, genetic testing for the GLDC gene usually uses a blood or saliva sample. A laboratory reads the gene’s DNA sequence and may also check for missing or extra pieces of DNA, which helps identify whether a GLDC variant is present.
When should I consider getting a genetic test?
Consider testing for the GLDC gene if a baby or child has unexplained seizures, severe sleepiness, weak muscle tone, feeding or breathing problems, or major developmental delays and doctors suspect a rare condition in which glycine builds up in the body. Testing can also help if this condition runs in the family or a previous child was affected.
A genetic result is only one part of your health story
A genetic result can provide useful insight, but how much it explains varies depending on the condition and the kind of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, influence how the body functions. For some conditions, especially those shaped by many genes, genetic information gives context rather than certainty and is best understood together with other parts of care. In other situations, a genetic result can offer a clear answer. In areas like medication response, genetic results can also help place personal experiences in context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how your body handles certain medicines, which helps explain why the same treatment may work well for one person but less well for another. Some people break down a drug more slowly or more quickly, while others may be more sensitive to its effects. These differences are common and can influence how well a medicine works or the chance of side effects. Genes are only one part of the picture, and age, other health conditions, and other medicines also matter.
What is Pharmacogenetics?
Pharmacogenetics focuses on how differences in genes affect the way people respond to medicines. It examines links between genes and drugs to help explain why the same treatment can work differently in different people. For many medicines, genes can influence how strongly a drug works or how the body handles it. Understanding this can support more informed and more individualized treatment decisions. More detailed information on this topic is available in the LearnHub.
Drugs influenced by the GLDC gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in predicting how medicines will work, so questions about side effects, new symptoms, or whether a treatment is right for you are best discussed with your doctor.