Fructosuria

Fructosuria

National Organization for Rare Disorders, Inc.

Important

It is possible that the main title of the report Fructosuria is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Synonyms

  • Essential Fructosuria
  • Hepatic Fructokinase Deficiency
  • Levulosuria
  • Ketohexokinase Deficiency

Disorder Subdivisions

  • None

General Discussion

Fructosuria is a rare but benign inherited metabolic disorder. It is characterized by the excretion of fruit sugar (fructose) in the urine. Normally, no fructose is excreted in the urine. This condition is caused by a deficiency of the enzyme fructokinase in the liver. This enzyme is needed for the synthesis of glycogen (the body's form of stored energy) from fructose. The presence of fructose in the blood and urine may lead to an incorrect diagnosis of diabetes mellitus.

Symptoms

Fructosuria is characterized by the presence of fructose in the urine. There are no other symptoms. However, the fructose may be mistaken for glucose (blood sugar) leading to an incorrect diagnosis of Diabetes Mellitus.

Causes

Fructosuria is a rare hereditary disorder transmitted as an autosomal recessive trait. The defective gene has been mapped to the Gene Map Locus 2p23.3-p23.2. Chromosomes, which are present in the nucleus of human cells, carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males, and two X chromosomes for females. Each chromosome has a short arm designated as "p" and a long arm identified by the letter "q". Chromosomes are further subdivided into many bands that are numbered. For example, chromosome 2p23.3 refers to band 23 on the short arm of chromosome 2.



Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.



All individuals carry 4-5 abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

Affected Populations

Fructosuria affects about 1 out of every 130,000 persons in the United States. It affects males and females in equal numbers.

Standard Therapies

Diagnosis of Fructosuria is made by testing the urine for the presence of fructose. Fructosuria does not require treatment as the symptoms are harmless.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.



For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:



Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov



For information about clinical trials sponsored by private sources, contact:

www.centerwatch.com

References

TEXTBOOKS

NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:444-45.



Gitzelmann R, Steinmann B, Van den Berghe G. In: Scriver CR, Beaudet AL, Sly WS, et al. Eds. The Metabolic Molecular Basis of Inherited Disease. 7th ed. McGraw-Hill Companies. New York, NY; 1995:905-34.



JOURNAL ARTICLES

Kozak M, Hayward B, Borek D, et al. Expression, purification and preliminary crystallographic studies of human ketohexokinase. Acta Crystallogr D Biol Crystallogr. 2001;57:586-88.



Boesiger P, Buchli R, Meier D, et al. Changes in liver metabolite concentrations in adults with disorders of fructose metabolism after intravenous fructose by 31P magnetic resonance spectroscopy. Pediatr Res. 1994;36:436-40.



Bonthron DT, Brady N, Donaldson IA, et al. Molecular basis of essential fructosuria: molecular cloning and mutational analysis of human ketohexokinase (fructokinase). Hum Mol Genet. 1994;3:1627-31.



Froesch ER. Disorders of fructose metabolism. 1976;5:599-611.



FROM THE INTERNET

McKusick VA, Ed. Online Mendelian Inheritance in Man (OMIM). The Johns Hopkins University. Entry Number; 229800: Last Edit Date; 11/1/1996.



Fructose Metabolism. nd. 4pp.

www.indstate.edu/home/mwking/non-glucose-sugar-metabolism.html



Monosaccharides and interconversion of sugars. Lecture 21. Dated: September 23, 2002:7pp.

www.uic.edu/depts/mcbc/curriculum/531/outline/21outline.pdf



Benign Fructosuria. PEDBASE. Last Updated: 8/01/1994:2pp.

www.icondata.com/health/pedbase/files/BENIGNFR.htm

Resources

CLIMB (Children Living with Inherited Metabolic Diseases)

Climb Building

176 Nantwich Road

Crewe, CW2 6BG

United Kingdom

Tel: 4408452412173

Fax: 4408452412174

Email: enquiries@climb.org.uk

Internet: http://www.CLIMB.org.uk



NIH/National Institute of Diabetes, Digestive & Kidney Diseases

Office of Communications & Public Liaison

Bldg 31, Rm 9A06

31 Center Drive, MSC 2560

Bethesda, MD 20892-2560

Tel: (301)496-3583

Email: NDDIC@info.niddk.nih.gov

Internet: http://www2.niddk.nih.gov/



Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223

Internet: http://rarediseases.info.nih.gov/GARD/



For a Complete Report

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