Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P00492 (hypoxanthine-guanine phosphoribosyltransferase)
 2,385 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypoxanthine-guanine phosphoribosyltransferase (HPRT, EC 2.4.2.8) is a purine salvage enzyme that catalyses the conversion of hypoxanthine and guanine to their respective mononucleotides. Partial deficiency of this enzyme can result in the overproduction of uric acid leading to a severe form of gout, whilst a virtual absence of HPRT activity causes the Lesch-Nyhan syndrome which is characterised by hyperuricaemia, mental retardation, choreoathetosis and compulsive self-mutilation. The HPRT-encoding gene is located on the X chromosome in the region q26-q27 and consists of nine exons and eight introns totalling 57 kb. This gene is transcribed to produce an mRNA of 1.6 kb, which contains a protein encoding region of 654 nucleotides. With the advent of increasingly refined techniques of molecular biology, it has been possible to study the HPRT gene of individuals with a deficiency in HPRT activity to determine the genetic basis of the enzyme deficiency. Many different mutations throughout the coding region have been described, but in the absence of precise information on the three-dimensional structure of the HPRT protein, it remains difficult to determine any consistent correlation between the structure and function of the enzyme.
 ...
PMID:A review of the molecular basis of hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency. 148 31

Lesch--Nyhan syndrome is an X-linked disease caused by the deficiency of hypoxanthine phosphoribosyltransferase, an enzyme involved in the purine salvage pathways. It is characterized by severe gout, choreoathetosis, self-mutilatory behaviour and mental retardation. The derivation of mice genetically deficient in this enzyme may help to elucidate the pathogenesis of the neurological abnormality where previously models using drug administration to mimic the disorder have had to suffice.
 ...
PMID:Mouse models of hypoxanthine phosphoribosyltransferase deficiency. 152 24

Lesch-Nyhan syndrome is a rare X-linked recessive disorder of purine metabolism associated with a virtually complete deficiency of the enzyme hypoxanthine-guanine phosphoribosyl-transferase (HPRT). The disease is characterized by hyperuricemia, self-multilation, choreoathetosis, spasticity, and mental retardation. The abnormalities of purine metabolism are present at birth and may lead to uric acid crystalluria and stone formation early in life. Radiographic findings described in Lesch-Nyhan syndrome include faintly radio-opaque stones on abdominal radiographs or, if renal disease is present, small kidneys with poor function on intravenous urogram. Radiolucent stones are usually composed of uric acid; however, several cases of xanthine and hypoxanthine-containing calculi in Lesch-Nyhan patients receiving allopurinl therapy have also been described. Oxypurine is the collective name for the compounds hypoxanthine, xanthine, and uric acid, and all may be radiolucent. We report a case of Lesch-Nyhan syndrome with presumed renal parenchymal oxypurine deposition demonstrated readily by ultrasonography but not detected on standard radiographs or intravenous urograms.
 ...
PMID:Renal oxypurine deposition in Lesch-Nyhan syndrome: sonographic evaluation. 267 3

Severe deficiency of hypoxanthine phosphoribosyltransferase (HPRT) in man results in the Lesch-Nyhan syndrome, an X-linked neurological disorder characterized by mental retardation, choreoathetosis and a compulsive tendency towards self-mutilation. Although the HPRT gene is normally constitutively expressed in all tissues at low levels, expression is elevated approximately fourfold in several regions of the central nervous system, particularly in the basal ganglia. The relationships between HPRT deficiency, tissue-specific alterations of nucleotide metabolism and the neuropathology of the Lesch-Nyhan syndrome remain unclear. Here we have microinjected recombinant molecules containing human HPRT (hHPRT) complementary DNA, the mouse metallothionein-I (MT-I) promoter and the 3'-untranslated portion of the human growth hormone (hGH) gene into mouse embryos to produce transgenic animals that express hHPRT on induction by cadmium. The hHPRT cDNA in these experiments contained 88 base pairs (bp) of 5'-untranslated and 190 bp of 3'-untranslated sequences, and the full-length coding sequence. We studied the in vivo expression of this MT-hHPRT fusion gene and observed preferential hHPRT expression in tissues of the central nervous system (CNS). This study suggests that sequences within the hHPRT transcript (cDNA) influence CNS expression via increased synthesis or stability of messenger RNA.
 ...
PMID:Expression of human HPRT in the central nervous system of transgenic mice. 299 15

Ten cases of Lesch-Nyhan syndrome have been followed for 3-19 years (mean, 11 years and four months). Criteria of Lesch-Nyhan syndrome were restricted to the following: complete absence of hypoxanthine-guanine phosphoribosyltransferase (HPRT) in hemolysate and fibroblast, spasticity, choreoathetosis, mental retardation, self-mutilation, and occurrence in males. Two patients have died of pneumonia and two died suddenly. However, autopsies produced no positive findings. Hyperuricemia has been controlled by benzbromarone in nine patients. One patient did not take any medical treatment and died suddenly when he was 19 years old, but showed no gouty signs. Patients with Lesch-Nyhan syndrome indicated no change or aggravation of choreoathetosis or spasticity. Self-mutilation was difficult to control by any treatment with continuing effect. After the age of ten, self-mutilation declined in seven cases, and in one patient disappeared completely. Mental delay was remarkable and suspected developmental age (DA) was 7 months - four years and 10 months (chronological age, 7 years and five months - 19 years and 6 months). Mean DQ score was 15.6. Physical development was severely delayed, and weight age was 28.9-46.4%, mean 37.4% of chronological age. Future investigations will evolve clarification of CNS signs and its treatment, and etiological research of sudden death.
 ...
PMID:Long-term follow-up of ten patients with Lesch-Nyhan syndrome. 376 72

The Lesch-Nyhan syndrome is characterized clinically by choreoathetosis, spasticity, selfmutilation, and mental and growth retardation. Biochemically, there is a striking reduction of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) activity in affected individuals. We have examined erythrocytes from 14 patients with the Lesch-Nyhan syndrome for the presence of hypoxanthine-guanine phosphoribosyltransferase activity and enzyme protein. In contrast to the usual finding of no detectable hypoxanthine-guanine phosphoribosyltransferase activity, we have found low levels (0.002-0.79 nmoles/mg protein per hr) of hypoxanthine-guanine phosphoribosyltransferase activity in erythrocyte lysates from five of these patients. In three of the five patients, hypoxanthine-guanine phosphoribosyltransferase activity appeared to be substantially more labile in vivo than normal using erythrocytes which had been separated according to their density (age). Immunochemical studies using a monospecific antiserum prepared from a homogeneous preparation of normal human erythrocyte hypoxanthine-guanine phosphoribosyltransferase revealed immunoreactive protein (CRM) in hemolysate from all 14 patients with the Lesch-Nyhan syndrome. The immunoreactive protein from each patient gave a reaction of complete identity with normal erythrocyte hypoxanthine-guanine phosphoribosyltransferase and was present in quantities equal to those observed in normal erythrocytes. In addition, a constant amount of CRM was found in erythrocytes of increasing density (age) from patients with the Lesch-Nyhan syndrome despite the decreasing hypoxanthine-guanine phosphoribosyltransferase activity. These studies confirm previous data which indicate that the mutations leading to the Lesch-Nyhan syndrome are usually, if not always on the structural gene coding for hypoxanthine-guanine phosphoribosyltransferase. In addition, although the mutant proteins appear to be present in normal amounts, they are often very labile in vivo with respect to enzymatic activity. These observations suggest that therapy directed at stabilization or activation of enzyme activity in vivo may be of potential benefit.
 ...
PMID:Hypoxanthine-guanine phosphoribosyltransferase: characteristics of the mutant enzyme in erythrocytes from patients with the Lesch-Nyhan syndrome. 462 52

A sex-linked familial neurological disease consisting of cerebral palsy, mental retardation, choreoathetosis, and compulsive aggressive behavior is associated with a loss of an enzyme that participates in purine metabolism, namely, hypoxanthine-guanine phosphoribosyltransferase. The production of excessive uric acid in this disorder implies that the enzyme is involved in the normal regulation of purine biosynthesis. This is the first example of a relation between a specific enzyme defect and abnormal compulsive behavior. It is also the first enzyme defect in purine metabolism demonstrated in a neurological disease.
 ...
PMID:Enzyme defect associated with a sex-linked human neurological disorder and excessive purine synthesis. 602 Feb 92

Different brain regions were removed post mortem from three patients with the Lesch-Nyhan syndrome and were examined for alterations in hypoxanthine-guanine phosphoribosyl transferase (HGPRT), adenine phosphoribosyl transferase, and biochemical indexes of norepinephrine, dopamine, serotonin, gamma-aminobutyric acid (GABA), and acetylcholine neuron function, as compared with age-matched controls. The level of HGPRT activity in the material from patients with the Lesch-Nyhan syndrome was less than 1 per cent of control levels, whereas adenyl phosphoribosyl transferase was not significantly altered. All biochemical aspects of the function of dopamine-neuron terminals in the striatum (except dihydroxyphenylacetic acid levels) were decreased to 10 to 30 per cent of the control values. Serotonin and 5-hydroxyindoleacetic acid levels were increased, striatal choline acetyltransferase levels were low, and striatal glutamic acid decarboxylase and guanylate cyclase activities were unaltered. The disruption of the balance between the functions of GABA, dopamine, and acetylcholine neurons in the extrapyramidal system probably accounts for some of the symptoms observed in the Lesch-Nyhan syndrome (e.g., choreoathetosis).
 ...
PMID:Biochemical evidence of dysfunction of brain neurotransmitters in the Lesch-Nyhan syndrome. 611 11

A large Arab family affected with the rare X-linked Lesch-Nyhan syndrome is reported on. Two hemizygous boys, two and nine years of age, had the classical biochemical and clinical-neurological syndrome. The activity of erythrocyte hypoxanthine-guanine phosphoribosyltransferase (HGPRT) was below the detectable limit (greater than 0.1% of normal). They were mentally and physically retarded and exhibited spasticity and choreoathetosis; the older of the two also exhibited self-mutilation. The mother and three of her seven daughters, all clinically asymptomatic, were proven to be heterozygous for HGPRT deficiency, by demonstration of an increased rate of de novo purine synthesis in cultured skin fibroblasts. Erythrocyte HGPRT activity was normal in the three heterozygous daughters, but was significantly reduced in the mother. However, in all four heterozygotes, erythrocyte HGPRT/adenine phosphoribosyltransferase ratio was lower than in all other family members. All heterozygotes had blood uric acid levels within the normal range, although higher than in the normal women in the family. The ratio uric acid/creatinine concentration in the urine was significantly elevated in one of the heterozygotes, and in the upper normal limit in two others, indicating excessive purine production.
 ...
PMID:Lesch-Nyhan syndrome in an Arab family. Detection and biochemical manifestation of heterozygosity. 732 17

Lesch-Nyhan syndrome is a rare X-linked disease characterized by over-production of uric acid and a central nervous system (CNS) disorder consisting of mental retardation, spasticity, choreoathetosis, and a compulsive form of self-mutilation. A deficiency in hypoxanthine-guanine phosphoribosyl transferase (HPRT) provides the underlying metabolic basis for this disease. A 12 month-old male baby who had orange crystals over the diapers since he was 3 months old was brought to our hospital due to developmental delay. Mental retardation and athetosis were also noted. Chemical analysis revealed hyperuricemia (uric acid 8.6 mg/dl). Urine routine showed microscopic hematuria and uric acid crystals. The activity of HPRT in erythrocyte lysates of parents were both within normal limits, but that of the patient was very low (0.0547 nm/min/mg protein, < 0.05% of control). His younger brother was born 2 months after this disorder diagnosed in this patient. The younger brother was noted to have uric acid crystals over the diapers when he was 40 days old and hyperuricemia (10.6 mg/dl) showed up later. He was also a case of Lesch-Nyhan syndrome since the activity of HPRT in erythrocyte lysates was also low (0.0327 nmol/min/mg protein, < 0.05% of control). Further studies, including carrier detection and deoxyribonucleic acid (DNA) analysis, could be helpful for genetic counseling. This syndrome is rare among Chinese, and this may be due to underdiagnosis.
 ...
PMID:Lesch-Nyhan Syndrome: report on two brothers. 783 90


1 2 3 Next >>