Pentosuria, essential

L-Xylulose Intermediate in uronic acid pathway. 1 I Found in urine in essential pentosuria. 

In the rare hereditary disease essential pentosuria, considerable quantities of L-xylulose appear in the urine because of absence of the enzyme necessary to reduce L-xylulose to xyhtol. Parenteral administration of xylitol may lead to oxalosis, involving calcium oxalate deposition in brain and kidneys (Figure 20-4). Various drugs markedly increase the rate at which glucose enters the... 

Lane AB (1985) On the nature of L-xylulose reductase deficiency in essential pentosuria. Biochem Genet 23 61-72... 

D-3) Essential pentosuria (deficiency of xylitol dehydrogenase). A benign accumulation of xylulose develops, which may be confused with glucose when detected in the urine. 

Essential pentosuria is a metabolic condition characterized by deficiency in the major isoform of L-xylulose reductases in human tissues homozygote individuals have only a residual activity of the enz)me [40], and thus excrete large concentrations of L-xylulose into urine. A minimum estimate of the Irequency of the pentosuria allele in an Ashkenazi-Jewish population is 0.0127 [41]. This metabolic disease is absolutely harmless, especially because the specific and selective anal)Tical techniques in use in modem diabetology should prevent a false positive diagnosis in essential pentosuria patients. 

L-Xylulose reductase (xylitol dehydrogenase) is deficient in essential pentosuria. L-Xylulose (a pentose) appears in the urine and gives a positive reducing-sugar test. The condition is benign. 

Occurrence. The ketopentose 14 (L-xylulose) is found in the urine of many cases of pentosuria.62 It was also detected in the serum of adult-onset diabetics.63 Essential pentosuria is the result of a partial deficiency of L-xylulose reductase.64... 

Essential pentosuria was first described in 1892 (S2), and it was one of the inborn errors of metabolism discussed by Garrod (Gl). It is distinguished from the other pentosurias by the nature of the pentose excreted (L-xylulose), the much larger amount of pentose excreted (1.1—3.7 g/24 hours) (L4), the constancy of the excretion irrespective of diet, and its occurrence primarily in individuals of Eastern European Jewish origin. Tousters (T2, T3) and Hiatt s (H4) studies of a patient with essential pentosuria indicate that there is a deficiency (or absence) in these individuals of the enzyme necessary for the conversion of L-xylu-lose to xylitol (Fig. 3). Direct demonstration of the enzyme deficiency has not been accomplished. 

Clinically, essential pentosuria is a benign disease and affected individuals have a normal life expectancy (LI). The only associated afiilic-tion is that of being mistakenly diagnosed and even treated for diabetes mellitus. 

L5. Lasker, M., Enklewitz, M., and Lasker, G. W., The inheritance of L-xyloketo-suria (essential pentosuria). Human Biol. 8, 243-255 (1936),... 

Pentosuria symptomless NADP Xylitol dehydrogenase deficiency Mendelian recessive trait Touster, 0. Essential pentosuria and the glu-curonatexylulose pathway. Fed. Proc. 19, 977-983 (1960)... 

Essential pentosuria is a benign inborn error of metabolism found mainly in Jews. It is due to a deficiency of xylitol dehydrogenase, an enzyme involved in the oxidation of glucuronic acid to pentoses. This results in increasing excretion of L-xylulose in the urine. The condition has a recessive mode of inheritance. 

NADP-linked Xylitol Dehydrogenase Deficiency. The enzyme catalyses the conversion of L-xylulose to xylitol of the non-oxidative branch of PP pathway. The symptom is known as essential pentosuria and was recognized as an inborn error of metabolism in 1892. Individuals excrete 1-4 g L-xylulose in urine per day. The disease is considered a benign condition that results from the defect in the glucuronic acid oxidation pathway [34-35]. 

---