Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018099 (gout)
 5,192 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Uric acid is the end-product of purine nucleotide metabolism in man. The renal handling of urate is a complicated process, resulting in a fractional clearance of 8.2-10.3%. The anhydrous form is thermodynamically the most stable uric acid crystal. Uric acid is a weak acid that ionizes with a Pka at pH 5.75. At the normal acidic region, uric acid solubility is strongly increased by urinary pH. The prevalence of uric acid stones varies between countries, reflecting climatic, dietary, and ethnical differences, ranging from 2.1% (in Texas) to 37.7% (in Iran). The risk for uric acid stone formation correlates with the degree of uric acid supersaturation in the urine, depending on uric acid concentration and urinary pH. Hyperuricosuria is the major risk factor, the most common cause being increased purine intake in the diet. Acquired and hereditary diseases accompanied by hyperuricosuria and stone disease include: gout, in strong correlation with the amount of uric acid excreted, myelo- and lymphoproliferative disorders, multiple myeloma, secondary polycythemia, pernicious anemia and hemolytic disorders, hemoglobinopathies and thalassemia, the complete or partial deficiency of HGPRT, superactivity of PRPP synthetase, and hereditary renal hypouricemia. A common denominator in patients with idiopathic and gouty stone formers is a low urinary pH. Uric acid nephrolithiasis is indicated in the presence of a radiolucent stone, a persistent undue urine acidity and uric acid crystals in fresh urine samples. A radiolucent stone in combination with normal or acidic pH should raise the possibility of urate stones.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Uric acid nephrolithiasis. 778 6

The molecular and biochemical aspects of purine nucleotide biosynthesis through de novo and salvage pathways, the production of uric acid, and their regulation mechanisms are reviewed for further understanding of hyperuricemia and gout. The metabolic rate of purine nucleotide biosynthesis is chiefly determined by the regulation of the de novo pathway, especially amidophosphoribosyltransferase and PRPP synthetase, and the accumulation of uric acid results from the acceleration of de novo biosynthesis and catabolism of purine nucleotide or the decrease in urinary excretion of uric acid. Moreover, several enzyme mutations of purine nucleotide metabolism are also clinically important including gout with hyperactive HPRT and the deficiency of HPRT (Lesch-Nyhan syndrome), adenylosuccinate lyase, xanthine oxidase, APRT, PNP, or ADA (SCID) with gene therapy.
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PMID:[Metabolism of purine nucleotides and the production of uric acid]. 897 90

We studied purine metabolism in gouty patients from three categories: primary gout, familial juvenile hyperuricaemic nephropathy (FJHN) and partial HPRT deficiency.
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PMID:How should we treat tophaceous gout in patients with allopurinol hypersensitivity? 959 24

Plasma uric acid concentration aggregates in families, and this similarity has been suggested to be due, in part, to multiple shared genes. Men have higher plasma uric acid concentrations than women and are affected with gout nine times more frequently. Rare forms of hyperuricemia and gout are due to mutations of X-linked genes (HPRT1 and PRPS1). Given these observations, we tested the hypothesis that normal variation in plasma uric acid levels would display a pattern of familial similarity consistent with X-linkage in 892 individuals from 196 obese but otherwise healthy families. As predicted by X-linked inheritance, fathers and sons showed no resemblance in plasma uric acid concentration (r = 0.013, NS), while all other pairings showed moderate-to-strong familial resemblance (ranging from 0.167, P < 0.01, parent-offspring to 0.415, sister-sister, P < 0.01). We then tested the hypothesis that loci along the X chromosome would influence plasma uric acid concentration. We conducted both single-point and multipoint linkage analyses using 17 X-linked markers spaced at approximately 9 cm intervals to determine whether allele sharing among sibs was related to sib similarity in plasma uric acid concentrations (n = 1,100 sib pairs). We found no regions of the X chromosome that cosegregated with plasma uric acid concentrations (P > 0.05). We conclude that variation in genes on the X chromosome contribute little to normal variation in plasma uric acid concentrations.
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PMID:X-linkage does not account for the absence of father-son similarity in plasma uric acid concentrations. 1079 40

Human embryonic stem (ES) cells are pluripotent cells derived from blastocyst-stage embryos. It has been suggested that these cells should play a major role in transplantation medicine and be able to advance our knowledge in human embryology. We propose that these cells should also play a vital role in the creation of models of human disorders. This aspect would be most valuable where animal models failed to faithfully recapitulate the human phenotype. Lesch-Nyhan disease is caused by a mutation in the HPRT1 gene that triggers an overproduction of uric acid, causing gout-like symptoms and urinary stones, in addition to neurological disorders. Due to biochemical differences between humans and rodents, a mouse lacking the HPRT expression will fail to accumulate uric acid. In this research we demonstrate a model for Lesch-Nyhan disease by mutating the HPRT1 gene in human ES cells using homologous recombination. We have verified the mutation in the HPRT1 allele at the DNA and RNA levels. By using selection media, we show that HPRT1 activity is abolished in the mutant cells, and the HPRT1-cells show a higher rate of uric acid accumulation than the wild-type cells. Therefore, these cells recapitulate to some extent the characteristics of Lesch-Nyhan syndrome and can help researchers further investigate this genetic disease and analyze drugs that will prevent the onset of its symptoms. We therefore suggest that human diseases may be modeled using human ES cells.
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PMID:Modeling for Lesch-Nyhan disease by gene targeting in human embryonic stem cells. 1527 9

Lesch-Nyhan syndrome (LSN, McKusick 300322) is an X-linked genetic disease due, in its typical form, to the complete absence of hypoxanthine-guanine phosphoribosyltransferase (HPRT, EC 2.4.2.8) enzyme activity. It is characterized by hyperuricaemia, leading to gout and kidney stones, accompanied by severe neurological dysfunction with self-injurious behaviour, choreoathetosis and spasticity. Based on a worldwide birth incidence estimate of about 1:380000, one or two new cases are expected every year in Italy. We performed biochemical and molecular genetic studies on 28 Italian patients from 25 families who are likely to represent most living individuals with the syndrome in the country. They all had absent HPRT activity and a typical LNS phenotype. Genetic analysis identified 24 HPRT mutations, 9 of which had not been previously reported: 74C>G (P25R), IVS2+1G>C, 194-195delTC, 329-332delCAAC insTCTs, IVS9-1G>A, 506insC, IVS8-1G>C, 606G>T (L202F), 418G>C (G140R). No mutation hotspots were identified. Only two mutations were found in more than one family, indicating the lack of any major mutation causing LNS in Italy. Three mutations arose de novo , two in the proband's mother, one in the maternal grandmother. The virtual complete absence of HPRT activity was related to deletions, nonsense, or missense mutations leading to nonconservative amino acid changes.
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PMID:Molecular basis of hypoxanthine-guanine phosphoribosyltransferase deficiency in Italian Lesch-Nyhan patients: identification of nine novel mutations. 1550 82

A deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT; EC 2.4.2.8) is associated with a spectrum of disease that ranges from gouty arthritis (OMIM 300323) to the more severe Lesch-Nyhan syndrome (OMIM 300322). To date, all cases of HPRT deficiency have shown a mutation within the HPRT cDNA. In the present study of an individual with gout due to HPRT deficiency, we found a normal HPRT cDNA sequence. This is the first study to provide an example of HPRT deficiency which appears to be due to a defect in the regulation of the gene.
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PMID:Normal HPRT coding region in a male with gout due to HPRT deficiency. 1586 84

Inherited mutations of a purine salvage enzyme, hypoxanthine guanine phosphoribosyltransferase (HPRT, EC 2.4.2.8), give rise to Lesch-Nyhan syndrome or HPRT-related gout. We have identified a number of HPRT mutations in Asian patients manifesting different clinical phenotypes, by analyzing all nine exons of the HPRT gene (HPRT1) from genomic DNA and reverse-transcribed mRNA using the PCR technique coupled with direct sequencing. In this study, we update the spectrum of mutations with nine novel mutations. Two missense mutations (T124P and D185G) were detected in patients with HRH (HPRT-related hyperuricemia). In a patient having a severe partial deficiency of HPRT with neurological dysfunction (HRND: HPRT-related neurological dysfunction), a single nucleotide substitution (27+5G > A) causing a splicing error was found in intron 1. The mutation resulted in a remarkably decreased level of normal mRNA, and production of an abnormal mRNA with a 49-bp insert at the 5'-end of intron 1, which caused the frame-shift of an amino acid codon (10fs27X). In six typical Lesch-Nyhan families, we found two 3-bp deletions responsible for single amino acid deletions (V8del and Y28del), two 1-bp deletions (440delA and 635delG) generating a frame-shift, an insertion of two amino acids (159insKV), and a 4,131-bp deletion from introns 4 to 6 resulting in two types of abnormal mRNA. Including these nine mutations, 42 HPRT1 mutations have been identified among 47 Asian families with deficiency of HPRT.
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PMID:Molecular analysis of HPRT deficiencies: an update of the spectrum of Asian mutations with novel mutations. 1702 11

Allopurinol is used widely for the treatment of purine disorders such as gout, but efficacy and safety of allopurinol has not been analyzed systematically in an extensive series of patients with HPRT deficiency. From 1984 to 2004 we have diagnosed 30 patients with HPRT deficiency. Eighteen patients (12 with Lesch-Nyhan syndrome or complete HPRT deficiency, and 6 with partial HPRT deficiency) were treated with allopurinol (mean dose, 6.44 mg/Kg of weight per day) and followed-up for at least 12 months (mean follow-up 7,6 years per patient). Mean age at diagnosis was 7 years (range, 5 months to 35 years). Treatment with allopurinol was associated to a mean reduction of serum urate concentration of 50%, and was normalized in all patients. Mean urinary uric acid excretion was reduced by 75% from baseline values, and uric acid to creatinine ratio was close or under 1.0 in all patients. In contrast, hypoxanthine and xanthine urinary excretion rates increased by a mean of 6 and 10 times, respectively, compared to baseline levels. These modifications were similar in patients with complete or partial HPRT deficiency. In 2 patients xanthine stones were documented despite allopurinol dose adjustments to prevent markedly increased oxypurine excretion rates. Neurological manifestations did not appear to be influenced by allopurinol therapy. Allopurinol is a very efficacy and fairly safety drug for the treatment of uric acid overproduction in patients with complete and partial HPRT deficiency. Allopurinol was associated with xanthine lithiasis.
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PMID:Efficacy and safety of allopurinol in patients with the Lesch-Nyhan syndrome and partial hypoxanthine- phosphoribosyltransferase deficiency: a follow-up study of 18 Spanish patients. 1706 67

We describe an HPRT deficiency in a 2-month-old child who presented acute renal failure and gout with normal mental and motor development for age. The patient was diagnosed with Lesch-Nyhan disease and showed a new mutation, a deletion of two bases in exon 3 of the HPRT gene (c.269-270delAT).
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PMID:HPRT deficiency in a two-month-old child presenting acute renal failure and gout with a new deletion of two bases in exon 3 of the HPRT gene. 1741 96


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