Encyclopedia
Essential pentosuria is a condition characterized by high levels of a sugar called L-xylulose in urine.
- genetic conditions
1. Introduction
The condition is so named because L-xylulose is a type of sugar called a pentose. Despite the excess sugar, affected individuals have no associated health problems.
2. Frequency
Essential pentosuria occurs almost exclusively in individuals with Ashkenazi Jewish ancestry. Approximately 1 in 3,300 people in this population are affected.
3. Causes
Essential pentosuria is caused by mutations in the DCXR gene. This gene provides instructions for making a protein called dicarbonyl and L-xylulose reductase (DCXR), which plays multiple roles in the body. One of its functions is to perform a chemical reaction that converts a sugar called L-xylulose to a molecule called xylitol. This reaction is one step in a process by which the body can use sugars for energy.
DCXR gene mutations lead to the production of altered DCXR proteins that are quickly broken down. Without this protein, L-xylulose is not converted to xylitol, and the excess sugar is released in the urine.
While essential pentosuria is caused by genetic mutations, some people develop a non-inherited form of pentosuria if they eat excessive amounts of fruits high in L-xylulose or another pentose called L-arabinose. This form of the condition, which disappears if the diet is changed, is referred to as alimentary pentosuria. Studies show that some drugs can also cause a form of temporary pentosuria called drug-induced pentosuria. These non-inherited forms of the condition also do not cause any health problems.
4. Inheritance
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
5. Other Names for This Condition
- essential benign pentosuria
- L-xylulose reductase deficiency
- L-xylulosuria
- pentosuria
- xylitol dehydrogenase deficiency
This entry is adapted from the peer-reviewed paper https://medlineplus.gov/genetics/condition/essential-pentosuria
References
- Ebert B, Kisiela M, Maser E. Human DCXR - another 'moonlighting protein'involved in sugar metabolism, carbonyl detoxification, cell adhesion and malefertility? Biol Rev Camb Philos Soc. 2015 Feb;90(1):254-78. doi:10.1111/brv.12108.
- Lane AB. On the nature of L-xylulose reductase deficiency in essentialpentosuria. Biochem Genet. 1985 Feb;23(1-2):61-72.
- Lee SK, Son le T, Choi HJ, Ahnn J. Dicarbonyl/l-xylulose reductase (DCXR): Themultifunctional pentosuria enzyme. Int J Biochem Cell Biol. 2013Nov;45(11):2563-7. doi: 10.1016/j.biocel.2013.08.010.
- Nakagawa J, Ishikura S, Asami J, Isaji T, Usami N, Hara A, Sakurai T,Tsuritani K, Oda K, Takahashi M, Yoshimoto M, Otsuka N, Kitamura K. Molecularcharacterization of mammalian dicarbonyl/L-xylulose reductase and itslocalization in kidney. J Biol Chem. 2002 May 17;277(20):17883-91.
- Pierce SB, Spurrell CH, Mandell JB, Lee MK, Zeligson S, Bereman MS, Stray SM, Fokstuen S, MacCoss MJ, Levy-Lahad E, King MC, Motulsky AG. Garrod's fourthinborn error of metabolism solved by the identification of mutations causingpentosuria. Proc Natl Acad Sci U S A. 2011 Nov 8;108(45):18313-7. doi:10.1073/pnas.1115888108.
