Renal hypouricemia is a heterogeneous inherited disorder characterized by impaired uric acid handling in the renal tubules. Patients are usually asymptomatic; however, some may experience urolithiasis and/or acute kidney injury. Most of the described patients (compound heterozygous and/or homozygous) are Japanese with mutations in the SLC22A12 gene (OMIM #220150). Four patients with renal hypouricemia caused by heterozygous defects and two families with homozygous mutations in the SLC2A9 gene have been recently described (OMIM #612076). We describe the clinical history, biochemical and molecular genetics findings of a Czech family with renal hypouricemia. The concentration of serum uric acid in the proband (16-year-old Czech girl with unrelated parents) was 0.17 ± 0.05 mg/dl and expressed as an increase in the fractional excretion of uric acid (194 ± 99%). The sequencing analysis of the coding region of uric acid transporters SLC22A12, SLC2A9, SLC17A3, ABCC4 and ABCG2, was performed. Analysis of genomic DNA revealed novel one nucleotide homozygote insertion in exon 3 in the SLC2A9 gene in proband and her brother resulting in a truncated protein (p.Ile118HisfsX27). No sequence variants in other candidate uric acid transporter were found. Homozygous loss-of-function mutations cause massive renal hypouricemia via total loss of uric acid absorption; however, they do not necessarily lead to nephrolithiasis and acute kidney injury. In contrast to previously reported heterozygous patients with renal hypouricemia type 2, we did not find even slight hypouricemia and found no decrease in the FE-UA of the heterozygous parents of the reported siblings.

• MeSH
• genetické asociační studie MeSH
• hodnoty glomerulární filtrace MeSH
• homozygot MeSH
• inzerční mutageneze MeSH
• kyselina močová krev   MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• močové kameny diagnóza   genetika   MeSH
• proteiny usnadňující transport glukosy genetika   MeSH
• rodokmen MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA MeSH
• studie případů a kontrol MeSH
• vrozené poruchy tubulárního transportu diagnóza   genetika   MeSH
• Check Tag
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH

Methods used in the project: retrospective cohort of 869 subjects, which were already biochemically and clinically characterized (the project ?Mild hyperhomocysteinemia in the Czech population: analysis of genetic factors among patients with atherosclerosis?, IGA MZ NM 26-3); selection of 150 subjects with normouricemia and 150 subjects with pathological level of serum uric acid. After identification of allelic variants (PCR amplification and seq. analysis) further detailed studies using expression system of Xenopus laevis oocytes including subcellular localization, colocalization, processing dynamics, transport of proteins and uptake studies will be performed. The identification of SLC2A9 and SLC22A12 allelic variants in statistically significant cohort of Czech population and their functional characterization will elucidate their frequency and influence on the level of serum uric acid and could contribute to the determination of relationship between genotype/fenotype in hypo/hyperuricemia.

Předmětem řešení projektu je identifikace a detailní funkční charakterizace alelických variant SLC2A9 a SLC22A12 v souboru 150 osob s normourikémií a 150 osob s nefyziologickými hodnotami kyseliny močové (gDNA již k dispozici, výběr ze souboru projektu "Mírná hyperhomocysteinemie v české populaci: analysa genetických faktorů u pacientů s atherosklerosou", IGA MZ NM 26-3). Nalezené alelické varianty (PCR amplifikace a sekv. analýza kódujících oblastí) budou funkčně a imunocytochemicky studovány expresnímsystémem využívající oocyty Xenopus laevis včetně subcelulární lokalizace, kolokalizačních studií, dynamiky procesování a transportu i transportní aktivity proteinů. Identifikace alelických variant majoritních urátových transportérů v statisticky významném vzorku české populace a jejich funkční charakterizace objasní četnost a vliv těchto variant na hodnoty sérové hladiny kyseliny močové a pravděpodobně přispěje k objasnění vztahu mezi genotypem a fenotypem u hypo/hyperurikémie.

• MeSH
• alely MeSH
• dna (nemoc) genetika   MeSH
• fenotyp MeSH
• genetické asociační studie MeSH
• genotyp MeSH
• hyperurikemie genetika   MeSH
• imunohistochemie MeSH
• kyselina močová krev   MeSH
• membránové transportní proteiny MeSH
• oocyty MeSH
• polymerázová řetězová reakce MeSH
• populace MeSH
• poruchy metabolismu purinů a pyrimidinů epidemiologie   genetika   MeSH
• přenašeče organických aniontů MeSH
• proteiny přenášející anionty MeSH
• sekvenční analýza DNA MeSH
• Xenopus laevis MeSH
• Geografické názvy
• Česká republika MeSH

• Konspekt
• Biochemie. Molekulární biologie. Biofyzika
• NLK Obory
• genetika, lékařská genetika
• biologie
• revmatologie
• NLK Publikační typ
• závěrečné zprávy o řešení grantu IGA MZ ČR

• Publikační typ
• abstrakt z konference MeSH

• Publikační typ
• abstrakt z konference MeSH

Urate transporters, which are located in the kidneys, significantly affect the level of uric acid in the body. We looked at genetic variants of genes encoding the major reabsorption proteins GLUT9 (SLC2A9) and URAT1 (SLC22A12) and their association with hyperuricemia and gout. In a cohort of 250 individuals with primary hyperuricemia and gout, we used direct sequencing to examine the SLC22A12 and SLC2A9 genes. Identified variants were evaluated in relation to clinical data, biochemical parameters, metabolic syndrome criteria, and our previous analysis of the major secretory urate transporter ABCG2. We detected seven nonsynonymous variants of SLC2A9. There were no nonsynonymous variants of SLC22A12. Eleven variants of SLC2A9 and two variants of SLC22A12 were significantly more common in our cohort than in the European population (p = 0), while variants p.V282I and c.1002+78A>G had a low frequency in our cohort (p = 0). Since the association between variants and the level of uric acid was not demonstrated, the influence of variants on the development of hyperuricemia and gout should be evaluated with caution. However, consistent with the findings of other studies, our data suggest that p.V282I and c.1002+78A>G (SLC2A9) reduce the risk of gout, while p.N82N (SLC22A12) increases the risk.

• Publikační typ
• časopisecké články MeSH

OBJECTIVE: Using European descent Czech populations, we performed a study of SLC2A9 and SLC22A12 genes previously identified as being associated with serum uric acid concentrations and gout. This is the first study of the impact of non-synonymous allelic variants on the function of GLUT9 except for patients suffering from renal hypouricemia type 2. METHODS: The cohort consisted of 250 individuals (150 controls, 54 nonspecific hyperuricemics and 46 primary gout and/or hyperuricemia subjects). We analyzed 13 exons of SLC2A9 (GLUT9 variant 1 and GLUT9 variant 2) and 10 exons of SLC22A12 by PCR amplification and sequenced directly. Allelic variants were prepared and their urate uptake and subcellular localization were studied by Xenopus oocytes expression system. The functional studies were analyzed using the non-parametric Wilcoxon and Kruskall-Wallis tests; the association study used the Fisher exact test and linear regression approach. RESULTS: We identified a total of 52 sequence variants (12 unpublished). Eight non-synonymous allelic variants were found only in SLC2A9: rs6820230, rs2276961, rs144196049, rs112404957, rs73225891, rs16890979, rs3733591 and rs2280205. None of these variants showed any significant difference in the expression of GLUT9 and in urate transport. In the association study, eight variants showed a possible association with hyperuricemia. However, seven of these were in introns and the one exon located variant, rs7932775, did not show a statistically significant association with serum uric acid concentration. CONCLUSION: Our results did not confirm any effect of SLC22A12 and SLC2A9 variants on serum uric acid concentration. Our complex approach using association analysis together with functional and immunohistochemical characterization of non-synonymous allelic variants did not show any influence on expression, subcellular localization and urate uptake of GLUT9.

• MeSH
• alely MeSH
• běloši MeSH
• biologický transport MeSH
• dna (nemoc) genetika   patologie   MeSH
• dospělí MeSH
• exprese genu MeSH
• frekvence genu MeSH
• hyperurikemie genetika   patologie   MeSH
• jednonukleotidový polymorfismus * MeSH
• lidé středního věku MeSH
• lidé MeSH
• přenašeče organických aniontů genetika   MeSH
• proteiny přenášející organické kationty genetika   MeSH
• proteiny usnadňující transport glukosy genetika   MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH

Renal hypouricemia (RHUC) is a pathological condition characterized by extremely low serum urate and overexcretion of urate in the kidney; this inheritable disorder is classified into type 1 and type 2 based on causative genes encoding physiologically-important urate transporters, URAT1 and GLUT9, respectively; however, research on RHUC type 2 is still behind type 1. We herein describe a typical familial case of RHUC type 2 found in a Slovak family with severe hypouricemia and hyperuricosuria. Via clinico-genetic analyses including whole exome sequencing and in vitro functional assays, we identified an intronic GLUT9 variant, c.1419+1G>A, as the causal mutation that could lead the expression of p.Gly431GlufsTer28, a functionally-null variant resulting from exon 11 skipping. The causal relationship was also confirmed in another unrelated Macedonian family with mild hypouricemia. Accordingly, non-coding regions should be also kept in mind during genetic diagnosis for hypouricemia. Our findings provide a better pathogenic understanding of RHUC and pathophysiological importance of GLUT9.

• Publikační typ
• časopisecké články MeSH

BACKGROUND: Renal hypouricemia (RHUC), a rare inherited disorder characterized by impaired uric acid (UA) reabsorption in the proximal tubule, is caused by mutations in SLC22A12 or SLC2A9. Most mutations have been identified in Japanese patients, and only a few have been detected in Europeans. METHODS: We report clinical, biochemical and genetics findings of fourteen Spanish patients, six Caucasians and eight of Roma ethnia, diagnosed with idiopathic RHUC. Two of the patients presented exercise-induced acute renal failure and another one had several episodes of nephrolithiasis and four of them had progressive deterioration of renal function, while the rest were asymptomatic. RESULTS: Molecular analysis revealed SLC22A12 mutations in ten of the patients, and SLC2A9 mutations in the other four. A new heterozygous SLC22A12 missense mutation, c.1427C>A (p.A476D), was identified in two affected members of the same family. The rest of the patients presented homozygous, heterozygous or compound heterozygous mutations that have been previously identified in patients with RHUC; SLC22A12 p.T467M and p.L415_G417del, and SLC2A9 p.T125M. Expression studies in Xenopus oocytes revealed that c.1427C>A reduced UA transport but did not alter the location of URAT1 protein on the plasma membrane. CONCLUSIONS: The biochemical and clinical features of our patients together with the genetic analysis results confirmed the diagnosis of RHUC. This is the first report describing SLC22A12 and SLC2A9 mutations in Spanish patients.

• MeSH
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• močové kameny genetika   MeSH
• mutace * MeSH
• předškolní dítě MeSH
• přenašeče organických aniontů genetika   MeSH
• proteiny přenášející organické kationty genetika   MeSH
• proteiny usnadňující transport glukosy genetika   MeSH
• rodokmen MeSH
• senioři MeSH
• vrozené poruchy tubulárního transportu genetika   MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Španělsko MeSH

Primary renal hypouricemia is a genetic disorder characterized by defective renal uric acid (UA) reabsorption with complications such as nephrolithiasis and exercise-induced acute renal failure. The known causes are: defects in the SLC22A12 gene, encoding the human urate transporter 1 (hURAT1), and also impairment of voltage urate transporter (URATv1), encoded by SLC2A9 (GLUT9) gene. Diagnosis is based on hypouricemia (<119 μmol/L) and increased fractional excretion of UA (>10%). To date, the cases with mutations in hURAT1 gene have been reported in East Asia only. More than 100 Japanese patients have been described. Hypouricemia is sometimes overlooked; therefore, we have set up the flowchart for this disorder. The patients were selected for molecular analysis from 620 Czech hypouricemic patients. Secondary causes of hyperuricosuric hypouricemia were excluded. The estimations of (1) serum UA, (2) excretion fraction of UA, and (3) analysis of hURAT1 and URATv1 genes follow. Three transitions and one deletion (four times) in SLC22A12 gene and one nucleotide insertion in SLC2A9 gene in seven Czech patients were found. Three patients had acute renal failure and urate nephrolithiasis. In addition, five nonsynonymous sequence variants and three nonsynonymous sequence variants in SLC2A9 gene were found in two UK patients suffering from acute renal failure. Our finding of the defects in SLC22A12 and SLC2A9 genes gives further evidence of the causative genes of primary renal hypouricemia and supports their important role in regulation of serum urate levels in humans.

• MeSH
• diagnostické techniky a postupy MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• močové kameny diagnóza   genetika   MeSH
• mutace genetika   MeSH
• přenašeče organických aniontů genetika   MeSH
• proteiny přenášející organické kationty genetika   MeSH
• proteiny usnadňující transport glukosy genetika   MeSH
• senioři MeSH
• vrozené poruchy tubulárního transportu diagnóza   genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Renal hypouricaemia is a heterogeneous inherited disorder characterized by impaired tubular uric acid transport with severe complications, such as acute kidney injury and nephrolithiasis. Type 1 is caused by a loss-of-function mutation in the SLC22A12 gene (OMIM #220150), while type 2 is caused by defects in the SLC2A9 gene (OMIM #612076). CASE-DIAGNOSIS/TREATMENT: The cases of two children, a 12- and a 14-year-old boy with acute kidney injury (proband 1: urea 9.4 mmol/l, creatinine 226 μmol/l; proband 2: urea 11.7 mmol/l, creatinine 202 μmol/l) are described. Both are offspring of nonconsanguineous couples in the UK. The concentrations of serum uric acid were consistently below the normal range (0.03 and 0.04 mmol/l) and expressed as an increase in the fractional excretion of uric acid (46 and 93 %). CONCLUSIONS: A sequencing analysis of the coding region of uric acid transporters SLC22A12 and SLC2A9 was performed. Analysis of genomic DNA revealed two unpublished missense transitions, p.G216R and p.N333S in the SLC2A9 gene. No sequence variants in SLC22A12 were found. Our findings suggest that homozygous and/or compound heterozygous loss-of-function mutations p.G216R and p.N333S cause renal hypouricaemia via loss of uric acid absorption and do lead to acute kidney injury.

• MeSH
• akutní poškození ledvin genetika   metabolismus   MeSH
• dítě MeSH
• kyselina močová metabolismus   MeSH
• lidé MeSH
• missense mutace MeSH
• mladiství MeSH
• močové kameny komplikace   genetika   metabolismus   MeSH
• mutační analýza DNA MeSH
• proteiny usnadňující transport glukosy genetika   MeSH
• vrozené poruchy tubulárního transportu komplikace   genetika   metabolismus   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH