Hereditary Fructose Intolerance

Gene : ALDOB

What is hereditary fructose intolerance?

Hereditary fructose intolerance is an inherited disorder caused by the lack of an enzyme called aldolase B. This enzyme is required for digestion of ingested fructose, a simple sugar found primarily in fruits. Affected individuals develop symptoms when fructose or sucrose is introduced into the diet in infancy. Ingestion of fructose- or sucrose-containing food causes abdominal pain, vomiting, and diarrhea. Persistent fructose intake can lead to severe low blood sugar, progressive liver damage and kidney failure, coma, and eventually death. People can be mildly or severely affected by this disease. By carefully removing fructose and sucrose in the diet, people may be symptom free. Intellectual disability is possible if the condition is left untreated. A careful diet may not prevent liver disease in some people who have a severe form of the disease. Hereditary fructose intolerance disease is caused by pathogenic variants in the ALDOB gene.

How is hereditary fructose intolerance inherited?

Hereditary fructose intolerance is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for hereditary fructose intolerance. However, the risk to have a child affected with hereditary fructose intolerance is increased. Testing of reproductive partners is recommended for carriers of hereditary fructose intolerance.

How common is hereditary fructose intolerance?

Hereditary fructose intolerance is estimated to occur in 1 in 20,000 to 30,000 newborns worldwide.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems



GI Tract


Carrier Rates
Detection Rate
Carrier Frequency
General Population 98% 1 in 55

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