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Normal Function
The ALDOB gene provides instructions for making the aldolase B enzyme. This enzyme is one of a group of three aldolase enzymes that are responsible for breaking down certain molecules in cells throughout the body. Four identical aldolase B enzymes need to be attached (bound) to each other in a four-enzyme unit called a tetramer to work.
Aldolase B is found primarily in the liver, but it is also present at lower levels in kidney and intestinal cells. Aldolase B is involved in the breakdown (metabolism) of the simple sugar fructose, which is found mostly in fruits and is used in the body for energy. Aldolase B is responsible for the second step in the metabolism of fructose, which breaks down the molecule fructose-1-phosphate into glyceraldehyde and dihydroxyacetone phosphate. To a lesser degree, aldolase B is also involved in the breakdown of the simple sugar glucose.
Health Conditions Related to Genetic Changes
Hereditary fructose intolerance
More than 50 mutations in the ALDOB gene have been found to cause hereditary fructose intolerance, a condition characterized by nausea and intestinal discomfort following ingestion of foods containing fructose. Most of these mutations replace single protein building blocks (amino acids) in the aldolase B enzyme and result in the production of an enzyme with reduced function. A mutation found in approximately half of people with hereditary fructose intolerance replaces the amino acid alanine with the amino acid proline at position 149 in the enzyme (written as Ala149Pro or A149P). This mutation alters the 3-dimensional shape of the enzyme. Alteration of the shape of the enzyme makes it difficult for the aldolase B enzymes to bind together and form tetramers. If it is not in a tetramer, aldolase B cannot metabolize fructose.
A lack of functional aldolase B results in an accumulation of fructose-1-phosphate in liver cells. This buildup is toxic, resulting in the death of liver cells over time. Additionally, the breakdown products of fructose-1-phosphase are needed in the body to produce energy and to maintain blood glucose levels. The combination of decreased cellular energy, low blood glucose, and liver cell death leads to the features of hereditary fructose intolerance.
More About This Health ConditionOther Names for This Gene
- ALDB
- ALDO2
- ALDOB_HUMAN
- aldolase 2
- aldolase B, fructose-bisphosphatase
- aldolase B, fructose-bisphosphate
- fructose-bisphosphate aldolase B
- liver-type aldolase
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
References
- Dalby AR, Tolan DR, Littlechild JA. The structure of human liver fructose-1,6-bisphosphate aldolase. Acta Crystallogr D Biol Crystallogr. 2001 Nov;57(Pt 11):1526-33. doi: 10.1107/s0907444901012719. Epub 2001 Oct 25. Citation on PubMed
- Esposito G, Vitagliano L, Santamaria R, Viola A, Zagari A, Salvatore F. Structural and functional analysis of aldolase B mutants related to hereditary fructose intolerance. FEBS Lett. 2002 Nov 6;531(2):152-6. doi: 10.1016/s0014-5793(02)03451-8. Citation on PubMed
- Malay AD, Allen KN, Tolan DR. Structure of the thermolabile mutant aldolase B, A149P: molecular basis of hereditary fructose intolerance. J Mol Biol. 2005 Mar 18;347(1):135-44. doi: 10.1016/j.jmb.2005.01.008. Epub 2005 Jan 20. Citation on PubMed
- Santer R, Rischewski J, von Weihe M, Niederhaus M, Schneppenheim S, Baerlocher K, Kohlschutter A, Muntau A, Posselt HG, Steinmann B, Schneppenheim R. The spectrum of aldolase B (ALDOB) mutations and the prevalence of hereditary fructose intolerance in Central Europe. Hum Mutat. 2005 Jun;25(6):594. doi: 10.1002/humu.9343. Citation on PubMed
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