The AASS gene helps your body break down lysine, an amino acid from food. This gene plays an important role in how your body processes protein from everyday foods. If both copies do not work well, lysine and related substances can build up in the blood and urine, causing hyperlysinemia. Many people with this condition remain well, while some may have developmental or neurologic findings that need medical follow-up.
What is a gene?
Genes are stretches of DNA that give cells instructions for making molecules or regulating activities in the body. Some genes carry the directions for producing proteins, which are the cell’s working parts. Others are used mainly to guide 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 influence your response to food, stress, and medicines. More detail on this topic is available in the LearnHub.
Overview
AASSGene function
What if the gene works
The AASS gene helps your body break down lysine, an amino acid from food. Its protein works mainly in mitochondria, helping cells process lysine and keep its levels in a healthy range.
Risk
What if the gene does not work
Variants in the AASS gene can cause hyperlysinemia, a buildup of the amino acid lysine. Many people have few or no symptoms, while more disruptive variants may be linked to developmental delay, low muscle tone, or seizures in some cases.
Treatment
What does that mean for your treatment
For people with pathogenic variants in the AASS gene, no AASS-specific treatment or drug selection approach is currently established. The AASS gene is being studied as a drug target to reduce lysine breakdown in conditions such as glutaric aciduria type 1 and ALDH7A1-related pyridoxine-dependent epilepsy.
Conditions associated with AASS
Gene function
What if the gene works
Your body uses the AASS gene to handle lysine, one of the building blocks of protein. It gives cells instructions for an enzyme in mitochondria, the parts of cells that help manage energy, that carries out the first steps of lysine breakdown. Understanding what the AASS gene does in the body helps explain how cells keep amino acid levels in balance.
The AASS gene helps your cells start breaking down lysine from food and normal protein turnover. This lets the body handle extra lysine in a controlled way and keep amino acid levels balanced.
Its protein carries out the first two linked steps in lysine breakdown. It first changes lysine into an intermediate form and then moves it on to the next stage.
This activity takes place in mitochondria, the parts of cells that help manage energy. By processing lysine there, the AASS gene supports routine nutrient handling inside the cell.
By moving lysine through its usual pathway, the AASS gene helps maintain a healthy balance of amino acids and related chemicals. This supports steady day to day metabolism across the body.
What is a variant?
A genetic variant is a minor change in the DNA sequence within a gene. These changes are common and help account for normal human diversity, including differences in appearance, metabolism, or how 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 substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the AASS gene can make its protein unstable, shorten it, or weaken one or both of its enzyme actions, which explains how AASS gene variants affect lysine breakdown inside cells. Milder variants may leave some activity in place, while more severe variants can lead to little or no working protein. This range in loss of function often influences how marked the biochemical changes are in hyperlysinemia.
How variants are linked to conditions
Pathogenic variants in the AASS gene cause hyperlysinemia, a rare inherited condition in which lysine levels are higher than usual in blood and urine. Most information about conditions linked to the AASS gene centers on this diagnosis. Many people with AASS-related hyperlysinemia have few or no symptoms, while some may have developmental delay, low muscle tone, or seizures.
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 directly affect health and instead represent normal human variation. For many genes, carrying a variant associated with a condition suggests a possible link rather than a confirmed diagnosis, especially when multiple 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?
There is not yet broadly confirmed evidence on specific factors that increase or reduce health risk related to the AASS gene. For many living with AASS changes, any effect depends mostly on the exact gene change and whether one or both copies are affected, rather than on lifestyle or environmental factors.
Inheritance of AASS variants
AASS-related conditions are inherited in an autosomal recessive pattern. This means a child usually needs to inherit two disease-causing variants in the AASS gene, one from each parent, to be affected. Parents who each carry one variant are often unaffected carriers, and with each pregnancy they have a 25% chance of having an affected child, a 50% chance of having a child who is a carrier, and a 25% chance of having a child with neither variant. In families asking how AASS gene variants are inherited, sons and daughters are affected at similar rates.
What does my AASS result mean for my family?
For families with an AASS-related condition, it usually runs in a recessive pattern, so parents are often healthy carriers and brothers or sisters may also be affected or be carriers. Close relatives may also carry the same gene change, especially on the parent’s side of the family. The meaning for each family member depends on whether they inherited one changed copy or two.
Genetic information
Genetic testing
How you find out about variants
To find out whether you carry a change in the AASS gene, doctors use genetic testing for AASS variants on a blood, saliva, or cheek swab sample. A lab reads the DNA sequence and checks for variants, then compares the result with known findings to show whether a variant is identified, absent, or unclear.
When should I consider getting a genetic test?
Genetic testing for the AASS gene may be worth considering if blood or urine tests show very high lysine levels, or if this inherited condition runs in the family. It can help confirm whether a change in AASS is the cause and whether other relatives may also carry it.
A genetic result is only one part of your health story
A genetic result can provide valuable insight, but how much it reveals depends on the condition and the kind of variant involved. How the body functions over time is shaped by many factors, including lifestyle, environment, age, and medical history. In some conditions, especially those affected by many genes, genetic information offers context rather than certainty and is best considered together with 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. One person may break down a drug more slowly, while another may process it faster, so the same dose can have different effects. This kind of difference is common and can influence how well a treatment works or how likely someone is to notice side effects. Pharmacogenetics looks at these inherited differences to help explain why medication response is not the same for everyone.
What is Pharmacogenetics?
Pharmacogenetics focuses on how genetic differences shape the response to medications. By examining links between genes and drugs, it helps explain why the same treatment can affect people in different ways. For many medicines, genes influence both how the body processes a drug and how strong its effects are. This information can support treatment decisions that are better informed and more individualized. To explore this topic further, more information is available in the LearnHub.
Drugs influenced by the AASS gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in how people respond to medicines, so questions about side effects, new symptoms, or whether a treatment is right for you are best discussed with your doctor.