We report the identification of two pathogenic variants in the ABCG2 gene, encoding a urate exporter, in two probands (male and female) with severe familial gouty phenotypes and hyperuricemia. Clinico-genetic analyses identified p.I63YfsTer54 (rs565722112) and p.G74D (rs199976573) as potentially causal mutations; functional analyses demonstrated that these two variants are deficient in plasma membrane localization and functionally null. Our data show that dysfunctional variants in the ABCG2 gene are strong risk factors for hyperuricemia and gout in both males and females.

• Klíčová slova
• ABCG2, Gout, Hyperuricemia, Urate transport,
• MeSH
• ABC transportér z rodiny G, člen 2 * genetika   metabolismus   MeSH
• dna (nemoc) * genetika   metabolismus   patologie   MeSH
• hyperurikemie * genetika   metabolismus   patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mutace * MeSH
• nádorové proteiny * genetika   metabolismus   MeSH
• senioři MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• Názvy látek
• ABC transportér z rodiny G, člen 2 * MeSH
• ABCG2 protein, human MeSH Prohlížeč
• nádorové proteiny * MeSH

Genetic variations in urate transporters play a significant role in determining human urate levels and have been implicated in developing hyperuricemia or gout. Polymorphism in the key urate transporters, such as ABCG2, URAT1, or GLUT9 was well-documented in the literature. Therefore in this study, our objective was to determine the frequency and effect of rare nonsynonymous allelic variants of SLC22A11, SLC22A13, and SLC17A1 on urate transport. In a cohort of 150 Czech patients with primary hyperuricemia and gout, we examined all coding regions and exon-intron boundaries of SLC22A11, SLC22A13, and SLC17A1 using PCR amplification and Sanger sequencing. For comparison, we used a control group consisting of 115 normouricemic subjects. To examine the effects of the rare allelic nonsynonymous variants on the expression, intracellular processing, and urate transporter protein function, we performed a functional characterization using the HEK293A cell line, immunoblotting, fluorescent microscopy, and site directed mutagenesis for preparing variants in vitro. Variants p.V202M (rs201209258), p.R343L (rs75933978), and p.P519L (rs144573306) were identified in the SLC22A11 gene (OAT4 transporter); variants p.R16H (rs72542450), and p.R102H (rs113229654) in the SLC22A13 gene (OAT10 transporter); and the p.W75C variant in the SLC17A1 gene (NPT1 transporter). All variants minimally affected protein levels and cytoplasmic/plasma membrane localization. The functional in vitro assay revealed that contrary to the native proteins, variants p.P519L in OAT4 (p ≤ 0.05), p.R16H in OAT10 (p ≤ 0.05), and p.W75C in the NPT1 transporter (p ≤ 0.01) significantly limited urate transport activity. Our findings contribute to a better understanding of (1) the risk of urate transporter-related hyperuricemia/gout and (2) uric acid handling in the kidneys.

• MeSH
• dna (nemoc) * genetika   MeSH
• hyperurikemie * genetika   MeSH
• kotransportní proteiny pro sodík a fosfát - typ I * genetika   MeSH
• kyselina močová metabolismus   MeSH
• lidé MeSH
• přenašeče organických aniontů nezávislé na sodíku * genetika   MeSH
• přenašeče organických aniontů * genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kotransportní proteiny pro sodík a fosfát - typ I * MeSH
• kyselina močová MeSH
• přenašeče organických aniontů nezávislé na sodíku * MeSH
• přenašeče organických aniontů * MeSH
• SLC17A1 protein, human MeSH Prohlížeč
• SLC22A11 protein, human MeSH Prohlížeč
• SLC22A13 protein, human MeSH Prohlížeč
• urate transporter MeSH Prohlížeč

The OAT1 (SLC22A6) and OAT3 (SLC22A8) urate transporters are located on the basolateral membrane of the proximal renal tubules, where they ensure the uptake of uric acid from the urine back into the body. In a cohort of 150 Czech patients with primary hyperuricemia and gout, we examined the coding regions of both genes using PCR amplification and Sanger sequencing. Variants p.P104L (rs11568627) and p.A190T (rs146282438) were identified in the gene for solute carrier family 22 member 6 (SLC22A6) and variants p.R149C (rs45566039), p.V448I (rs11568486) and p.R513Q (rs145474422) in the gene solute carrier family 22 member 8 (SLC22A8). We performed a functional study of these rare non-synonymous variants using the HEK293T cell line. We found that only p.R149C significantly reduced uric acid transport in vitro. Our results could deepen the understanding of uric acid handling in the kidneys and the molecular mechanism of uric acid transport by the OAT family of organic ion transporters.

• Klíčová slova
• OAT1, OAT3, gout, hyperuricemia, urate transport,
• MeSH
• biologický transport MeSH
• dna (nemoc) * genetika   metabolismus   MeSH
• HEK293 buňky MeSH
• hyperurikemie * genetika   MeSH
• kyselina močová metabolismus   MeSH
• lidé MeSH
• přenašeče organických aniontů nezávislé na sodíku * genetika   MeSH
• protein 1 přenášející organické anionty * genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kyselina močová MeSH
• organic anion transport protein 3 MeSH Prohlížeč
• přenašeče organických aniontů nezávislé na sodíku * MeSH
• protein 1 přenášející organické anionty * MeSH

OBJECTIVES: MicroRNAs (miRNAs) are short single-stranded RNAs that play a role in the post-transcriptional regulation of gene expression. Their deregulation can be associated with various diseases, such as cancer, neurodegenerative, and immune-related diseases. The aim of our study was to compare miRNA levels in plasma that could potentially influence the progression of hyperuricemia to gout, since the mechanism of progression is still unclear. METHODS: Total RNA, including miRNA, was isolated from the plasma of 45 patients with asymptomatic hyperuricemia, 131 patients with primary gout (including 16 patients having a gout attack), and 130 normouricemic controls. The expression of 18 selected miRNAs (cel-miR-39 and cel-miR-54 as spike-in controls, hsa-miR-16-5p and hsa-miR-25-3p as endogenous controls, hsa-miR-17-5p, hsa-miR-18a-5p, hsa-miR-30a-3p, hsa-miR-30c-5p, hsa-miR-126-3p, hsa-miR-133a-3p, hsa-miR-142-3p, hsa-miR-143-3p, hsa-miR-146a-5p, hsa-miR-155-5p, hsa-miR-222-3p, hsa-miR-223-3p, hsa-miR-488-3p and hsa-miR-920) was measured using qPCR. RESULTS: We found that hsa-miR-17-5p, hsa-miR-18a-5p, hsa-miR-30c-5p, hsa-miR-142-3p, and hsa-miR-223-3p were significantly upregulated (p < 0.001) in the plasma of hyperuricemia and gout patients compared to normouricemic individuals. As part of the follow-up of our previous study, we found a negative correlation between hsa-miR-17-5p, hsa-miR-30c-5p, hsa-miR-126-3p, hsa-miR-142-3p, and hsa-miR-223-3p with plasma levels of chemokine MCP-1. Additionally, we found a positive correlation between CRP and plasma levels of hsa-miR-17-5p, hsa-miR-18a-5p, hsa-miR-30c-5p, hsa-miR-126-3p, hsa-miR-142-3p, hsa-miR-146a-5p, hsa-miR-155-5p, hsa-miR-222-3p, and hsa-miR-223-3p. Five of those miRNAs (hsa-miR-126-3p, hsa-miR-142-3p, hsa-miR-146a-5p, hsa-miR-155-5p, and hsa-miR-222-3p) also had a positive correlation with serum creatinine and therefore a negative correlation with eGFR. CONCLUSION: Five miRNAs were significantly upregulated in the plasma of patients with hyperuricemia and gout (and those during a gout attack) compared to normouricemic controls. We also found a correlation between the plasma levels of several miRNA and plasma levels of MCP-1, CRP, serum creatinine, and eGFR.

• Klíčová slova
• Acute gouty arthritis, Gout, Hyperuricemia, Uric acid, miRNA,
• MeSH
• cirkulující mikroRNA * MeSH
• dna (nemoc) * genetika   MeSH
• hyperurikemie * genetika   MeSH
• kvantitativní polymerázová řetězová reakce MeSH
• lidé MeSH
• mikro RNA * genetika   MeSH
• regulace genové exprese MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cirkulující mikroRNA * MeSH
• mikro RNA * MeSH

The ABCG2 gene is a well-established hyperuricemia/gout risk locus encoding a urate transporter that plays a crucial role in renal and intestinal urate excretion. Hitherto, p.Q141K-a common variant of ABCG2 exhibiting approximately one half the cellular function compared to the wild-type-has been reportedly associated with early-onset gout in some populations. However, compared with adult-onset gout, little clinical information is available regarding the association of other uricemia-associated genetic variations with early-onset gout; the latent involvement of ABCG2 in the development of this disease requires further evidence. We describe a representative case of familial pediatric-onset hyperuricemia and early-onset gout associated with a dysfunctional ABCG2, i.e., a clinical history of three generations of one Czech family with biochemical and molecular genetic findings. Hyperuricemia was defined as serum uric acid (SUA) concentrations 420 μmol/L for men or 360 μmol/L for women and children under 15 years on two measurements, performed at least four weeks apart. The proband was a 12-year-old girl of Roma ethnicity, whose SUA concentrations were 397-405 µmol/L. Sequencing analyses focusing on the coding region of ABCG2 identified two rare mutations-c.393G>T (p.M131I) and c.706C>T (p.R236X). Segregation analysis revealed a plausible link between these mutations and hyperuricemia and the gout phenotype in family relatives. Functional studies revealed that p.M131I and p.R236X were functionally deficient and null, respectively. Our findings illustrate why genetic factors affecting ABCG2 function should be routinely considered in clinical practice as part of a hyperuricemia/gout diagnosis, especially in pediatric-onset patients with a strong family history.

• Klíčová slova
• ABCG2 genotype, Roma, SUA-lowering therapy, clinico-genetic analysis, ethnic specificity, genetic variations, precision medicine, rare variant, serum uric acid, urate transporter,
• MeSH
• ABC transportér z rodiny G, člen 2 genetika   metabolismus   MeSH
• dítě MeSH
• dna (nemoc) komplikace   genetika   MeSH
• dospělí MeSH
• fenotyp MeSH
• genetická predispozice k nemoci MeSH
• HEK293 buňky MeSH
• hyperurikemie krev   komplikace   genetika   MeSH
• jednonukleotidový polymorfismus * MeSH
• kyselina močová krev   MeSH
• lidé MeSH
• mutace MeSH
• nádorové proteiny genetika   metabolismus   MeSH
• přenašeče organických aniontů genetika   metabolismus   MeSH
• rodokmen MeSH
• transfekce MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• ABC transportér z rodiny G, člen 2 MeSH
• ABCG2 protein, human MeSH Prohlížeč
• kyselina močová MeSH
• nádorové proteiny MeSH
• přenašeče organických aniontů MeSH
• urate transporter MeSH Prohlížeč

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.

• Klíčová slova
• SLC22A12, SLC2A9, gout, hyperuricemia, sequencing, urate transporters,
• Publikační typ
• časopisecké články MeSH

Gout is an inflammatory arthritis influenced by environmental risk factors and genetic variants. The common dysfunctional p.Q141K allele of the ABCG2 gene affects gout development. We sought after the possible association between the p.Q141K variant and gout risk factors, biochemical, and clinical determinants in hyperuricemic, gouty, and acute gouty arthritis cohorts. Further, we studied the correlation of p.Q141K allele and levels of pro-/anti-inflammatory cytokines. Coding regions of the ABCG2 gene were analyzed in 70 primary hyperuricemic, 182 gout patients, and 132 normouricemic individuals. Their genotypes were compared with demographic and clinical parameters. Plasma levels of 27 cytokines were determined using a human multiplex cytokine assay. The p.Q141K variant was observed in younger hyperuricemic/gout individuals (p = 0.0003), which was associated with earlier disease onset (p = 0.004), trend toward lower BMI (p = 0.056), and C-reactive protein (CRP, p = 0.007) but a higher glomerular filtration rate (GFR, p = 0.035). Levels of 19 cytokines were higher, mainly in patients with acute gouty arthritis (p < 0.001), irrespective of the presence of the p.Q141K variant. The p.Q141K variant influences the age of onset of primary hyperuricemia or gout and other disease-linked risk factors and symptoms. There was no association with cytokine levels in the circulation.

• Klíčová slova
• ABCG2, acute gouty arthritis, cytokines, gout, hyperuricemia, p.Q141K,
• Publikační typ
• časopisecké články MeSH

ATP-binding cassette subfamily G member 2 (ABCG2) is a physiologically important urate transporter. Accumulating evidence demonstrates that congenital dysfunction of ABCG2 is an important genetic risk factor in gout and hyperuricemia; recent studies suggest the clinical significance of both common and rare variants of ABCG2. However, the effects of rare variants of ABCG2 on the risk of such diseases are not fully understood. Here, using a cohort of 250 Czech individuals of European descent (68 primary hyperuricemia patients and 182 primary gout patients), we examined exonic non-synonymous variants of ABCG2. Based on the results of direct sequencing and database information, we experimentally characterized nine rare variants of ABCG2: R147W (rs372192400), T153M (rs753759474), F373C (rs752626614), T421A (rs199854112), T434M (rs769734146), S476P (not annotated), S572R (rs200894058), D620N (rs34783571), and a three-base deletion K360del (rs750972998). Functional analyses of these rare variants revealed a deficiency in the plasma membrane localization of R147W and S572R, lower levels of cellular proteins of T153M and F373C, and null urate uptake function of T434M and S476P. Accordingly, we newly identified six rare variants of ABCG2 that showed lower or null function. Our findings contribute to deepening the understanding of ABCG2-related gout/hyperuricemia risk and the biochemical characteristics of the ABCG2 protein.

• Klíčová slova
• ABCG2/BCRP, European cohort, WGA., common disease, exon sequence, functional study, gout susceptibility, heritability of serum uric acid, multiple rare variant, urate transporter,
• MeSH
• ABC transportér z rodiny G, člen 2 genetika   metabolismus   MeSH
• běloši genetika   MeSH
• biologický transport MeSH
• dítě MeSH
• dna (nemoc) krev   genetika   metabolismus   MeSH
• dospělí MeSH
• genetická predispozice k nemoci MeSH
• HEK293 buňky MeSH
• hyperurikemie krev   genetika   MeSH
• jednonukleotidový polymorfismus MeSH
• kohortové studie MeSH
• kyselina močová krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• nádorové proteiny genetika   metabolismus   MeSH
• předškolní dítě MeSH
• přenašeče organických aniontů metabolismus   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• ABC transportér z rodiny G, člen 2 MeSH
• ABCG2 protein, human MeSH Prohlížeč
• kyselina močová MeSH
• nádorové proteiny MeSH
• přenašeče organických aniontů MeSH
• urate transporter MeSH Prohlížeč

BACKGROUND: ABCG2 is a high-capacity urate transporter that plays a crucial role in renal urate overload and extra-renal urate underexcretion. Previous studies have suggested an association between hyperuricemia and gout susceptibility relative to dysfunctional ABCG2 variants, with rs2231142 (Q141K) being the most common. In this study, we analyzed the ABCG2 gene in a hyperuricemia and gout cohort focusing on patients with pediatric-onset, i.e., before 18 years of age. METHOD: The cohort was recruited from the Czech Republic (n = 234) and consisted of 58 primary hyperuricemia and 176 gout patients, with a focus on pediatric-onset patients (n = 31, 17 hyperuricemia/14 gouts); 115 normouricemic controls were used for comparison. We amplified, sequenced, and analyzed 15 ABCG2 exons. The chi-square goodness-of-fit test was used to compare minor allele frequencies (MAF), and the log-rank test was used to compare empirical distribution functions. RESULTS: In the pediatric-onset cohort, two common (p.V12M, p.Q141K) and three very rare (p.K360del, p.T421A, p.T434M) allelic ABCG2 variants were detected. The MAF of p.Q141K was 38.7% compared to adult-onset MAF 21.2% (OR = 2.4, P = 0.005), to the normouricemic controls cohort MAF 8.5% (OR = 6.8, P < 0.0001), and to the European population MAF 9.4% (OR = 5.7, P < 0.0001). The MAF was greatly elevated not only among pediatric-onset gout patients (42.9%) but also among patients with hyperuricemia (35.3%). Most (74%) of the pediatric-onset patients had affected family members (61% were first-degree relatives). CONCLUSION: Our results show that genetic factors affecting ABCG2 function should be routinely considered in a hyperuricemia/gout diagnosis, especially in pediatric-onset patients. Genotyping of ABCG2 is essential for risk estimation of gout/hyperuricemia in patients with very early-onset and/or a family history.

• Klíčová slova
• ABCG2, Gout, Hyperuricemia, Urate transport,
• MeSH
• ABC transportér z rodiny G, člen 2 genetika   MeSH
• alopurinol terapeutické užití   MeSH
• antiuratika terapeutické užití   MeSH
• dítě MeSH
• dna (nemoc) diagnóza   farmakoterapie   genetika   MeSH
• dospělí MeSH
• febuxostat terapeutické užití   MeSH
• frekvence genu MeSH
• genetická predispozice k nemoci genetika   MeSH
• genotyp MeSH
• hyperurikemie diagnóza   farmakoterapie   genetika   MeSH
• jednonukleotidový polymorfismus * MeSH
• kohortové studie MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• předškolní dítě MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• ABC transportér z rodiny G, člen 2 MeSH
• alopurinol MeSH
• antiuratika MeSH
• febuxostat MeSH

• Klíčová slova
• Excretion fraction of uric acid *, Hypouricemia *, SLC22A12 *, URAT1 *, Urate transport *,
• MeSH
• akutní poškození ledvin krev   prevence a kontrola   moč   MeSH
• alopurinol aplikace a dávkování   MeSH
• antioxidancia aplikace a dávkování   MeSH
• cystinóza krev   diagnóza   moč   MeSH
• diferenciální diagnóza MeSH
• dítě MeSH
• Fanconiho syndrom krev   diagnóza   moč   MeSH
• genetické testování MeSH
• kyselina močová krev   metabolismus   moč   MeSH
• ledvinové kanálky metabolismus   MeSH
• lidé MeSH
• močové kameny krev   diagnóza   genetika   moč   MeSH
• přenašeče organických aniontů genetika   MeSH
• proteiny přenášející organické kationty genetika   MeSH
• proteiny usnadňující transport glukosy genetika   MeSH
• renální reabsorpce MeSH
• syndrom nepřiměřené sekrece ADH krev   diagnóza   moč   MeSH
• vrozené poruchy tubulárního transportu krev   diagnóza   genetika   moč   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• Názvy látek
• alopurinol MeSH
• antioxidancia MeSH
• kyselina močová MeSH
• přenašeče organických aniontů MeSH
• proteiny přenášející organické kationty MeSH
• proteiny usnadňující transport glukosy MeSH
• SLC22A12 protein, human MeSH Prohlížeč
• SLC2A9 protein, human MeSH Prohlížeč