Hereditary fructose intolerance: Difference between revisions
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The deficient enzyme is [[aldolase-B]], which converts [[fructose-1-phosphate]] to [[DHAP]] and [[glyceraldehyde]]. This means that the fructose cannot be further metabolised beyond fructose-1-phosphate. This traps [[phosphate]]s; which are needed to [[phosphorylate]] [[glycogen phosphorylase]] which carries on to release units of [[glucose-1-phosphate]] from glycogen. (Glucose-1-phosphate gets converted to [[glucose-6-phosphate]] and then dephosphorylated to form [[glucose]]). | The deficient enzyme is [[aldolase-B]], which converts [[fructose-1-phosphate]] to [[DHAP]] and [[glyceraldehyde]]. This means that the fructose cannot be further metabolised beyond fructose-1-phosphate. This traps [[phosphate]]s; which are needed to [[phosphorylate]] [[glycogen phosphorylase]] which carries on to release units of [[glucose-1-phosphate]] from glycogen. (Glucose-1-phosphate gets converted to [[glucose-6-phosphate]] and then dephosphorylated to form [[glucose]]). | ||
In addition, [[aldolase-B]] plays an important role in [[gluconeogenesis]], producing [[fructose-1,6-bisphosphate]] from [[glyceraldehyde-3-phosphate]] and DHAP. Thus, glucose cannot be released through the breakdown of [[glycogen]] nor can it be synthesized from [[gluconeogenesis]], resulting in severe [[hypoglycaemia|hypoglycemia]]. Hereditary fructose intolerance is inherited. If both parents are carriers for [[aldolase B]] gene, each of their children has a 25% (1 in 4) chance of being affected. | In addition, [[aldolase-B]] plays an important role in [[gluconeogenesis]], producing [[fructose-1,6-bisphosphate]] from [[glyceraldehyde-3-phosphate]] and DHAP. Thus, glucose cannot be released through the breakdown of [[glycogen]] nor can it be synthesized from [[gluconeogenesis]], resulting in severe [[hypoglycaemia|hypoglycemia]]. Hereditary fructose intolerance is [[inherited]]. If both parents are carriers for [[aldolase B]] gene, each of their children has a 25% (1 in 4) chance of being affected. | ||
==Differentiating {{PAGENAME}} from Other Diseases== | ==Differentiating {{PAGENAME}} from Other Diseases== | ||
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==Natural History, Complications, and Prognosis== | ==Natural History, Complications, and Prognosis== | ||
=== Natural History === | |||
* Early symptoms are similar to those of galactosemia (inability to use the sugar galactose). Later symptoms relate more to liver disease. Symptoms may include: convulsions, excessive sleepiness, Irritability, jaundice, poor feeding and growth, failure to thrive, vomiting. | |||
* The symptoms of hereditary fructose intolerance typically develop when the baby starts eating fruits and other foods that contain fructose or sucrose. | |||
==Diagnosis== | ==Diagnosis== | ||
Revision as of 21:29, 26 June 2021
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
Hereditary fructose intolerance (HFI) or fructose poisoning is a hereditary condition caused by a deficiency of liver enzymes that metabolise fructose.
Historical Perspective
Classification
Pathophysiology
Presentation
If fructose is ingested, other symptoms such as vomiting, hypoglycemia, jaundice, hemorrhage, hepatomegaly, hyperuricemia and eventually kidney failure will follow.
Causes
The deficient enzyme is aldolase-B, which converts fructose-1-phosphate to DHAP and glyceraldehyde. This means that the fructose cannot be further metabolised beyond fructose-1-phosphate. This traps phosphates; which are needed to phosphorylate glycogen phosphorylase which carries on to release units of glucose-1-phosphate from glycogen. (Glucose-1-phosphate gets converted to glucose-6-phosphate and then dephosphorylated to form glucose).
In addition, aldolase-B plays an important role in gluconeogenesis, producing fructose-1,6-bisphosphate from glyceraldehyde-3-phosphate and DHAP. Thus, glucose cannot be released through the breakdown of glycogen nor can it be synthesized from gluconeogenesis, resulting in severe hypoglycemia. Hereditary fructose intolerance is inherited. If both parents are carriers for aldolase B gene, each of their children has a 25% (1 in 4) chance of being affected.
Differentiating Hereditary fructose intolerance from Other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications, and Prognosis
Natural History
- Early symptoms are similar to those of galactosemia (inability to use the sugar galactose). Later symptoms relate more to liver disease. Symptoms may include: convulsions, excessive sleepiness, Irritability, jaundice, poor feeding and growth, failure to thrive, vomiting.
- The symptoms of hereditary fructose intolerance typically develop when the baby starts eating fruits and other foods that contain fructose or sucrose.
Diagnosis
Diagnostic Criteria
History and Symptoms
Physical Examination
Laboratory Findings
Imaging Findings
Other Diagnostic Studies
Treatment
Treatment is with a fructose free diet, which if adhered to, is concordant with a good prognosis. [1]
Fructose and sucrose eliminated from diet. [2]
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
Related conditions
Hereditary fructose intolerance should not be confused with fructose malabsorption. The latter is the same as dietary fructose intolerance (DFI), a deficiency of fructose transporter enzyme in the enterocytes, which leads to abdominal bloating, diarrhea and/or constipation.
See also
External links
- Boston University HFI Lab
- http://www.uihealthcare.com/topics/medicaldepartments/foodandnutrition/dfi/whatisdfi.html
- Food-Info.net Fructose Intolerance (with list of acceptable and non-acceptable carbohydrates)
- [2]
- HFI-Info Discussion Board