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

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

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

OBJECTIVE: The first ever genome-wide association study (GWAS) of clinically defined gout cases and asymptomatic hyperuricaemia (AHUA) controls was performed to identify novel gout loci that aggravate AHUA into gout. METHODS: We carried out a GWAS of 945 clinically defined gout cases and 1003 AHUA controls followed by 2 replication studies. In total, 2860 gout cases and 3149 AHUA controls (all Japanese men) were analysed. We also compared the ORs for each locus in the present GWAS (gout vs AHUA) with those in the previous GWAS (gout vs normouricaemia). RESULTS: This new approach enabled us to identify two novel gout loci (rs7927466 of CNTN5 and rs9952962 of MIR302F) and one suggestive locus (rs12980365 of ZNF724) at the genome-wide significance level (p<5.0×10-8). The present study also identified the loci of ABCG2, ALDH2 and SLC2A9. One of them, rs671 of ALDH2, was identified as a gout locus by GWAS for the first time. Comparing ORs for each locus in the present versus the previous GWAS revealed three 'gout vs AHUA GWAS'-specific loci (CNTN5, MIR302F and ZNF724) to be clearly associated with mechanisms of gout development which distinctly differ from the known gout risk loci that basically elevate serum uric acid level. CONCLUSIONS: This meta-analysis is the first to reveal the loci associated with crystal-induced inflammation, the last step in gout development that aggravates AHUA into gout. Our findings should help to elucidate the molecular mechanisms of gout development and assist the prevention of gout attacks in high-risk AHUA individuals.

• Klíčová slova
• asymptomatic hyperuricemia, genome-wide association study, gout, individually-tailored preemptive medicine, uric acid,
• MeSH
• ABC transportér z rodiny G, člen 2 genetika   MeSH
• asymptomatické nemoci MeSH
• celogenomová asociační studie MeSH
• dna (nemoc) krev   genetika   MeSH
• dospělí MeSH
• genetické lokusy genetika   MeSH
• genotypizační techniky MeSH
• hyperurikemie genetika   MeSH
• kontaktiny genetika   MeSH
• kyselina močová krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mikro RNA genetika   MeSH
• mitochondriální aldehyddehydrogenasa genetika   MeSH
• nádorové proteiny genetika   MeSH
• proteiny usnadňující transport glukosy genetika   MeSH
• rizikové faktory MeSH
• zinkové prsty genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• metaanalýza MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ABC transportér z rodiny G, člen 2 MeSH
• ABCG2 protein, human MeSH Prohlížeč
• ALDH2 protein, human MeSH Prohlížeč
• CNTN5 protein, human MeSH Prohlížeč
• kontaktiny MeSH
• kyselina močová MeSH
• mikro RNA MeSH
• MIRN302A microRNA, human MeSH Prohlížeč
• mitochondriální aldehyddehydrogenasa MeSH
• nádorové proteiny MeSH
• proteiny usnadňující transport glukosy MeSH
• SLC2A9 protein, human MeSH Prohlížeč

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