Essential pentosuria (Essential pentosuria) - Gen DCXR.
The essential pentosuria is a disease characterized by high concentrations in the urine of a sugar called L-xylulose. Despite the excess sugar, those affected have no associated health problems. This disease occurs almost exclusively in individuals of Ashkenazi Jewish descent.
This process is due to mutations in the gene DCXR, located on the long arm of chromosome 17 (17q25.3). This gene encodes a protein called dicarbonyl / L-xylulose reductase (DCXR) plays multiple functions in the body. One of its functions is to perform a chemical reaction that converts L-xylulose to xylitol. This reaction is a step in a process by which the organism can synthesise sugars for energy. Two versions of L-xylulose reductase in the body, known as the major isoform and lower isoform. The DCXR gene encodes the major isoform, which converts L-xylulose more efficiently than the smaller isoform way. It is unclear if the smallest isoform is encoded from DCXR gene or another gene. Another function of the protein is decomposed DCXR alpha-dicarbonyl toxic compounds. These compounds, which are byproducts of certain cellular processes or in foods in the diet, must be decomposed to not damage the cells. The DCXR protein is also one of several proteins that bind to the surface of sperm cells as they mature. DCXR is involved in the interaction of a sperm cell with an egg during fertilization.
They have identified at least 2 mutations in the gene responsible for essential pentosuria DCXR. The identified mutations lead to altered protein coding DCXR rapidly decompose. Without this protein, L-xylulose is not converted to xylitol efficient manner, and excess sugar is released into the urine. Only the major isoform of L-xylulose reductase is affected by these mutations, but the smaller isoform can not compensate for the loss of function of DCXR in the breakdown of L-xylulose. It is believed that other processes are able to decompose the alpha-dicarbonyl toxic compounds, which probably explains the absence of symptoms in people with essential pentosuria. Although studies show that a protein deficiency DCXR in sperm cells may be associated with infertility, men with essential pentosuria appear to have normal reproductive function.
This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.
Tests in IVAMI: in IVAMI perform detection of mutations associated with essential pentosuria, by complete PCR amplification of exons DCXR gene, and subsequent sequencing.
Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).