Your liver, kidneys, and small intestine use the ALDOB gene to break down fructose, a sugar found in fruit, honey, table sugar, and sorbitol. If this gene does not work properly, fructose can build up and upset the body’s energy balance. Pathogenic variants in the ALDOB gene cause hereditary fructose intolerance, which can lead to vomiting, sweating, belly pain, low blood sugar, and poor growth after fructose is eaten. Avoiding fructose, sucrose, and sorbitol usually helps prevent symptoms.
What is a gene?
A gene is a piece of DNA that holds instructions cells use to make molecules or regulate processes in the body. Some genes provide the directions for producing 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 also influence how you respond to food, stress, and medications. For a deeper look at this topic, more information is available in the LearnHub.
Overview
ALDOBGene function
What if the gene works
The ALDOB gene helps the liver, kidneys, and small intestine break down fructose, a sugar found in fruit, table sugar, and many sweetened foods. This supports energy use and helps keep sugar processing balanced.
Risk
What if the gene does not work
ALDOB gene changes can cause hereditary fructose intolerance, where fructose builds up in the liver and kidneys. After fructose, sucrose, or sorbitol, people may develop vomiting, low blood sugar, and liver problems; milder or more severe variants can change severity.
Treatment
What does that mean for your treatment
A pathogenic variant in the ALDOB gene means treatment centers on lifelong avoidance of fructose, sucrose, and sorbitol, including in medicines, supplements, and IV fluids. Care teams use glucose or dextrose when calories or IV sugar are needed. With strict avoidance, symptoms usually improve and liver and kidney problems can stabilize.
Conditions associated with ALDOB
Gene function
What if the gene works
When you eat fruit, table sugar, or foods sweetened with fructose, your cells need a clear way to process that sugar. The ALDOB gene gives instructions for a protein that helps with those steps, mainly in the liver, kidneys, and small intestine. This helps explain what the ALDOB gene does in the body during everyday sugar use.
The ALDOB gene helps cells split a sugar compound called fructose-1-phosphate after fructose is absorbed from food. This turns fructose into smaller pieces that cells can use for energy or other normal body needs.
Its protein also helps split fructose-1,6-bisphosphate, a step used in routine sugar handling inside cells. This supports normal energy release and helps the body manage glucose use between meals.
Many cells carrying this gene change their sugar-processing activity depending on where they are in the body, and ALDOB is especially active in the liver. In that setting, it supports smooth day to day handling of dietary sugars.
What is a variant?
Within a gene, a genetic variant is a small change in its DNA sequence. These changes are common and help shape normal human diversity, including differences in appearance, metabolism, and how the body responds to environmental influences. Many variants have no noticeable effect and are simply part of natural genetic variation. In some cases, though, a variant can change 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 ALDOB gene can change the shape or stability of the aldolase B enzyme, so it works less well or not at all. This explains how ALDOB gene variants affect fructose metabolism and underlie hereditary fructose intolerance, because fructose-1-phosphate can build up inside cells. Some variants leave partial enzyme activity and may be linked to milder or later symptoms, while more disruptive variants often cause little or no activity and earlier, more pronounced symptoms.
How variants are linked to conditions
Pathogenic variants in the ALDOB gene cause hereditary fructose intolerance, a genetic condition in which symptoms often begin after fructose, sucrose, or sorbitol are introduced into the diet. In practice, ALDOB gene variants linked to hereditary fructose intolerance can lead to vomiting, low blood sugar, liver problems, feeding difficulties, and poor growth. People who carry one pathogenic variant are usually healthy, while a diagnosis is typically confirmed when both copies of the ALDOB gene have pathogenic variants.
A variant is not necessarily a diagnosis
Genetic variants are a routine feature of human biology and are widely found across the general population. Most do not directly affect health and simply reflect the natural diversity seen among people. For many genes, having a variant associated with a condition points to a possible link rather than a certain diagnosis, particularly when several genes and environmental influences also play a role. In other situations, though, one well understood variant in a particular gene may be enough to confirm a diagnosis.
Are there things that can increase or change my risk?
For ALDOB, the main risk is inherited: hereditary fructose intolerance usually happens when a child receives two changed copies of the ALDOB gene, one from each parent. For people living with this condition, illness is triggered by fructose, table sugar, or sorbitol in foods, drinks, or medicines, so exposure can worsen symptoms and raise the chance of complications.
Inheritance of ALDOB variants
ALDOB-related hereditary fructose intolerance follows an autosomal recessive inheritance pattern, which explains how ALDOB variants are inherited in families. A child usually develops the condition only if they inherit one ALDOB variant from each parent. Parents who each carry one variant are typically unaffected carriers, and with each pregnancy there is a 25% chance their child will have the condition, a 50% chance the child will be a carrier, and a 25% chance the child will inherit neither variant.
What does my ALDOB result mean for my family?
For families with an ALDOB-related condition, close relatives may also carry the same gene change, even if they feel completely well. Brothers and sisters could be affected or be carriers, and parents are usually carriers. Other relatives, such as future children and extended family members, may also want to learn whether the change runs in the family.
Genetic information
Genetic testing
How you find out about variants
To find ALDOB variants, a lab usually analyzes DNA from a blood sample, saliva, or a cheek swab. ALDOB genetic testing reads the ALDOB gene to look for variants linked to hereditary fructose intolerance and can show whether you carry a harmful variant. Results are interpreted alongside symptoms and family history.
When should I consider getting a genetic test?
Genetic testing for the ALDOB gene may be worth considering if a child or adult has strong reactions after eating fructose, table sugar, or sorbitol, such as vomiting, sweating, low blood sugar, or liver problems. It can also help when hereditary fructose intolerance runs in the family or a close relative has a known ALDOB variant.
A genetic result is only one part of your health story
A genetic result can be informative, although how much it reveals varies depending on the condition and the kind of variant involved. Over time, the way the body works is also shaped by many factors, 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 considered alongside other parts of care. In other situations, a genetic result may offer 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 a person responds to medicines. Small differences in genes can change how the body breaks down a drug, moves it through the body, or responds at the drug’s target, so the same treatment may work well for one person but less well for another. This is common and can influence how much benefit someone gets or how likely they are to notice side effects.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in a person’s genes can affect their response to medicines. It studies patterns between genes and drugs to help explain why the same treatment may work differently in different people. For many drugs, genes can influence both how the body handles a medicine and how strong its effects are. This understanding can support more informed, personalized treatment choices. More detail on this topic is available in the LearnHub.
Drugs influenced by the ALDOB 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 used, so any concerns about side effects, new symptoms after starting a treatment, or questions about your medicines are best discussed with your doctor.
History
Hereditary fructose intolerance was recognized in the mid 20th century, when doctors noticed that some infants became very unwell after starting fruit, juices, or foods sweetened with sugar. Initially understood only through visible traits, later recognized as tied to a specific gene, this condition was linked to the ALDOB gene as biochemical and genetic research advanced in the 1980s and 1990s. From these first observations, research expanded steadily, and scientists identified recurring ALDOB variants in affected families from different parts of the world. That work helped confirm inheritance patterns and improved diagnosis for children and adults with unexplained reactions to fructose. Over time, descriptions became more precise, and ALDOB became an established part of the history of inherited metabolic conditions.