Joint effects of alcohol consumption and ABCG2 Q141K on chronic tophaceous gout risk

Gene Dose-Dependent and Additive Effects of ABCG2 rs2231142 and SLC2A9 rs3733591 Genetic Polymorphisms on Serum Uric Acid Levels

This study aimed to evaluate whether the single nucleotide polymorphisms of ATP-binding cassette subfamily G member 2 (ABCG2) and solute carrier family 2 member 9 (SLC2A9) affect individual blood uric acid levels using pyrosequencing. ABCG2 (rs2231142, rs72552713, rs2231137), SLC2A9 (rs3734553, rs3733591, rs16890979), and individual uric acid levels were prospectively analyzed in 250 healthy young Korean male participants. Prominent differences in uric acid levels of the alleles were observed in the SLC2A9 rs3733591 polymorphism: wild-type (AA) vs. heterozygote (AG), 0.7 mg/dL (p < 0.0001); AA vs. mutant type (GG), 1.32 mg/dL (p < 0.0001); and AG vs. GG, 0.62 mg/dL (p < 0.01). In ABCG2 single nucleotide polymorphisms (SNPs), the statistically significant differences in uric acid levels were only found in rs2231142 between CC vs. AA (1.06 mg/dL; p < 0.001), and CC vs. CA (0.59 mg/dL; p < 0.01). Serum uric acid levels based on the ABCG2 and SLC2A9 diplotype groups were also compared. The uric acid levels were the lowest in the CC/AA diplotype and highest in the AA/AG diplotype. In addition, the SNP SLC2A9 rs3733591 tended to increase the uric acid levels when the ABCG2 rs2231142 haplotypes were fixed. In conclusion, both the ABCG2 rs2231142 and SLC2A9 rs3733591 polymorphisms may additively elevate blood uric acid levels.

Moving the Needle in Gout Management: The Role of Culture, Diet, Genetics, and Personalized Patient Care Practices

Gout is a metabolic disorder, and one of the most common inflammatory arthritic conditions, caused by elevated serum urate (SU). Gout is globally rising, partly due to global dietary changes and the growing older adult population. Gout was known to affect people of high socioeconomic status. Currently, gout disproportionately affects specific population subgroups that share distinct racial and ethnic backgrounds. While genetics may predict SU levels, nongenetic factors, including diet, cultural traditions, and social determinants of health (SDOH), need to be evaluated to optimize patient treatment outcomes. This approach would allow clinicians to assess whether certain cultural norms, or some SDOH, could be contributing to their patient’s risk of developing gout or recurrent gout flares. A cultural assessment may inform the development of culturally tailored dietary recommendations for patients with gout. Causal and association studies investigating the interaction between diet, genetics, and gout, should be cautiously interpreted due to the lack of reproducibility in different racial groups. Optimal gout management could benefit from a multidisciplinary approach, involving pharmacists and nurses. While data on the effect of specific dietary recommendations on managing hyperuricemia and gout may be limited, counseling patients with gout on the role of a healthy diet to optimally control their gout flares and other comorbidities should be part of patient education. Future research investigating the role of a gene–diet interaction in the context of hyperuricemia and gout is needed. Optimal care for patients with gout needs to include a holistic assessment for gout and gout-related comorbidities. Additionally, addressing health beliefs and culture-specific lifestyle factors among patients with gout may reduce their risk of gout flare, improve adherence to urate-lowering therapy (ULT), and achieve health equity in gout management.

Trends in the Contribution of Genetic Susceptibility Loci to Hyperuricemia and Gout and Associated Novel Mechanisms

Hyperuricemia and gout are complex diseases mediated by genetic, epigenetic, and environmental exposure interactions. The incidence and medical burden of gout, an inflammatory arthritis caused by hyperuricemia, increase every year, significantly increasing the disease burden. Genetic factors play an essential role in the development of hyperuricemia and gout. Currently, the search on disease-associated genetic variants through large-scale genome-wide scans has primarily improved our understanding of this disease. However, most genome-wide association studies (GWASs) still focus on the basic level, whereas the biological mechanisms underlying the association between genetic variants and the disease are still far from well understood. Therefore, we summarized the latest hyperuricemia- and gout-associated genetic loci identified in the Global Biobank Meta-analysis Initiative (GBMI) and elucidated the comprehensive potential molecular mechanisms underlying the effects of these gene variants in hyperuricemia and gout based on genetic perspectives, in terms of mechanisms affecting uric acid excretion and reabsorption, lipid metabolism, glucose metabolism, and nod-like receptor pyrin domain 3 (NLRP3) inflammasome and inflammatory pathways. Finally, we summarized the potential effect of genetic variants on disease prognosis and drug efficacy. In conclusion, we expect that this summary will increase our understanding of the pathogenesis of hyperuricemia and gout, provide a theoretical basis for the innovative development of new clinical treatment options, and enhance the capabilities of precision medicine for hyperuricemia and gout treatment.

Examining an Association of Single Nucleotide Polymorphisms with Hyperuricemia in Chinese Flight Attendants

Background

Both genetic and environmental factors strongly affect serum uric acid (SUA) concentrations. The incidence of hyperuricemia tends to be younger in the Chinese population. In particular, we have found a high prevalence of hyperuricemia among Chinese flight attendants, aged from 20 to 40, in our survey. This study aims to evaluate whether there is an association between gene polymorphisms and hyperuricemia among Chinese flight attendants.

Methods

A total of 532 flight attendants with high and normal serum uric acid levels were recruited. Allele-specific polymerase chain reaction (AS-PCR) was performed using blood samples of enrolled subjects.

Results

Previous studies have reported single nucleotide polymorphisms (SNPs) that are tightly associated with uric acid levels. Among them, six SNPs that are strongly associated with SUA or gout in Asians, for instance ABCG2 (rs2231142, rs72552713 and rs2231137), GCKR (rs780094), SLC2A9 (rs1014290) and SLC17A1 (rs1183201), were selected for AS-PCR analyses. We found that SNPs such as ABCG2 rs2231142, GCKR rs780094 and SLC2A9 rs1014290 are strongly associated with hyperuricemia in male flight attendants, and SLC2A9 rs1014290 among female flight attendants.

Conclusion

Our study provides evidences of an association between SNPs and hyperuricemia in the Chinese flight attendants, and highlights the significance of improving diagnostics and prevention of disease development in uric acid metabolism disorders and gout using these SNPs.

Gout associated with reduced renal excretion of uric acid. Renal tubular disorder that nephrologists do not treat

Gout is recurrent inflammatory arthritis caused by the deposition of monosodium urate crystals in the joints. The risk factors that predispose to suffering from gout include non-modifiable factors such as gender, age, ethnicity and genetics, and modifiable factors such as diet and lifestyle. It has been shown that the heritability of uric acid levels in the blood is greater than 30%, which indicates that genetics play a key role in these levels. Hyperuricaemia is often a consequence of reduced renal urate excretion since more than 70% is excreted by the kidneys, mainly through the proximal tubule. The mechanisms that explain that hyperuricaemia associated with reduced renal urate excretion is, to a large extent, a proximal renal tubular disorder, have begun to be understood following the identification of two genes that encode the URAT1 and GLUT9 transporters. When they are carriers of loss-of-function mutations, they explain the two known variants of renal tubular hypouricaemia. Some polymorphisms in these genes may have an opposite gain-of-function effect, with a consequent increase in urate reabsorption. Conversely, loss-of-function polymorphisms in other genes that encode transporters involved in urate excretion (ABCG2, ABCC4) can lead to hyperuricaemia. Genome-wide association study (GWAS) methods have made it possible to locate new gout-related loci associated with reduced renal urate excretion (NIPAL1, FAM35A).

Interaction of Alcohol Consumption and ABCG2 rs2231142 Variant Contributes to Hyperuricemia in a Taiwanese Population

Background: ABCG2 rs2231142 is an important genetic factor that contributes to the development of gout and hyperuricemia (HUA). Epidemiologic studies have demonstrated that lifestyle risk factors of HUA (e.g., alcohol consumption) and genetic predisposition (e.g., ABCG2 gene) together, contribute to enhanced serum uric acid levels. However, the interaction between ABCG2 rs2231142, alcohol consumption, and HUA in the Taiwanese population is still unclear. Therefore, this study investigated whether the risk of HUA is associated with ABCG2 rs2231142 variants and how this is affected by alcohol consumption. Method: study subjects were selected from the participants of the Taiwan Biobank database. Overall, 114,540 participants aged 30 to 70 years were enrolled in this study. The interaction between ABCG2 rs2231142, alcohol consumption, and serum uric acid (sUA) levels was analyzed by multiple logistic regression models. Results: the prevalence of HUA was 32.7% and 4.4 % in the male and female populations, respectively. In the whole study population, the minor T allele of ABCG2 rs2231142 was significantly associated with HUA risk, and the occurrence of HUA was high in TT genotype and TG genotype. The risk of HUA was significantly increased by the combined association of ABCG2 rs2231142 and alcohol consumption for TG/TT genotype compared to the GG genotype (wild-type genotype), especially among women. Conclusion: the ABCG2 rs2231142 is a crucial genetic locus for sUA levels in the Taiwanese population and our findings revealed that alcohol consumption combined with the ABCG2 rs2231142 risk allele contributes to increased HUA risk.

Gout associated with reduced renal excretion of uric acid. Renal tubular disorder that nephrologists do not treat

Gout is recurrent inflammatory arthritis caused by the deposition of monosodium urate crystals in the joints. The risk factors that predispose to suffering from gout include non-modifiable factors such as gender, age, ethnicity and genetics, and modifiable factors such as diet and lifestyle. It has been shown that the heritability of uric acid levels in the blood is greater than 30%, which indicates that genetics play a key role in these levels. Hyperuricaemia is often a consequence of reduced renal urate excretion since more than 70% is excreted by the kidneys, mainly through the proximal tubule. The mechanisms that explain that hyperuricaemia associated with reduced renal urate excretion is, to a large extent, a proximal renal tubular disorder, have begun to be understood following the identification of two genes that encode the URAT1 and GLUT9 transporters. When they are carriers of loss-of-function mutations, they explain the two known variants of renal tubular hypouricaemia. Some polymorphisms in these genes may have an opposite gain-of-function effect, with a consequent increase in urate reabsorption. Conversely, loss-of-function polymorphisms in other genes that encode transporters involved in urate excretion (ABCG2, ABCC4) can lead to hyperuricaemia. Genome-wide association study (GWAS) methods have made it possible to locate new gout-related loci associated with reduced renal urate excretion (NIPAL1, FAM35A).

Pathophysiology of Gout

Multiple interacting checkpoints are involved in the pathophysiology of gout. Hyperuricemia is the key risk factor for gout and is considered a prerequisite for monosodium urate (MSU) crystal formation. Urate underexcretion through renal and gut mechanisms is the major mechanism for hyperuricemia in most people. Multiple genetic, environmental, and metabolic factors are associated with serum urate and alter urate transport or synthesis. Urate supersaturation is the most important factor for MSU crystal formation, and other factors such as temperature, pH, and connective tissue components also play a role. The nucleotide-binding oligomerization domain leucine-rich repeats and pyrin domain-containing protein 3 inflammasome plays a pivotal role in the inflammatory response to MSU crystals, and interleukin 1β is the key cytokine mediating the inflammatory cascade. Variations in the regulatory mechanisms of this inflammatory response may affect an individual's susceptibility to developing gout. Tophus formation is the cardinal feature of advanced gout, and both MSU crystals and the inflammatory tissue component of the tophus contribute to the development of structural joint damage owing to gout. In this article, we review the pathophysiologic mechanisms of hyperuricemia, MSU crystal formation and the associated inflammatory response, tophus formation, and structural joint damage in gout.

The association between genetic polymorphisms in ABCG2 and SLC2A9 and urate: an updated systematic review and meta-analysis

Background

Replication studies showed conflicting effects of ABCG2 and SLC2A9 polymorphisms on gout and serum urate. This meta-analysis therefore aimed to pool their effects across studies.

Methods

Studies were located from MEDLINE and Scopus from inception to 17th June 2018. Observational studies in adults with any polymorphism in ABCG2 or SLC2A9, and outcome including gout, hyperuricemia, and serum urate were included for pooling. Data extractions were performed by two independent reviewers. Genotype effects were pooled stratified by ethnicity using a mixed-effect logistic model and a multivariate meta-analysis for dichotomous and continuous outcomes.

Results

Fifty-two studies were included in the analysis. For ABCG2 polymorphisms, mainly studied in Asians, carrying 1–2 minor-allele-genotypes of rs2231142 and rs72552713 were respectively about 2.1–4.5 and 2.5–3.9 times higher odds of gout than non-minor-allele-genotypes. The two rs2231142-risk-genotypes also had higher serum urate about 11–18 μmol/l. Conversely, carrying 1–2 minor alleles of rs2231137 was about 36–57% significantly lower odds of gout. For SLC2A9 polymorphisms, mainly studied in Caucasians, carrying 1–2 minor alleles of rs1014290, rs6449213, rs6855911, and rs7442295 were about 25–43%, 31–62%, 33–64%, and 35–65% significantly lower odds of gout than non-minor-allele-genotypes. In addition, 1–2 minor-allele-genotypes of the latter three polymorphisms had significantly lower serum urate about 20–49, 21–51, and 18–54 μmol/l than non-minor-allele-genotypes.

Conclusions

Our findings should be useful in identifying patients at risk for gout and high serum urate and these polymorphisms may be useful in personalized risk scores.

Trial registration

PROSPERO registration number: CRD42018105275.

Supplementary information

The online version contains supplementary material available at 10.1186/s12881-020-01147-2.

The haplotype of SLC2A9_rs3733591, PKD2_rs2725220 and ABCG2_rs2231142 increases the hyperuricaemia risk and alcohol, chicken and processed meat intakes and smoking interact with its risk

We determined that a genetic haplotype increased the risk of hyperuricaemia and it interacted with lifestyle factors, including nutrients in 28,445 middle-aged Koreans. ABCG2_rs2231142, PKD2_rs2725220 and SLC2A9_rs3733591 were selected from GWAS based on hyperuricaemia (≥7 mg/dL; p = 6.88E-42, 1.56E-26 and 1.01E-20, respectively). Hyperuricaemia and gout were elevated by 3.93- and 3.23-fold, respectively, by the minor alleles as compared with the major alleles of the haplotype of the selected 3 SNPs after adjusting for covariates. The haplotype significantly interacted with alcohol, chicken and processed meat intakes, and smoking status in the hyperuricaemia risk (p = 0.002-0.007). Minor alleles of the haplotype had an association with hyperuricaemia as compared with major alleles particularly in high intakes of alcohol (2g/day), chicken (6.3g/day), and processed meat (3g/day) and smokers. In conclusion, people carrying minor alleles of the haplotype of SLC2A9_rs3733591, PKD2_rs2725220 and ABCG2_rs2231142 should avoid diets high in chicken and processed meat, alcohol drinking, and cigarette smoking to protect against hyperuricaemia risk.

Distinct diagnostic and prognostic values of γ-aminobutyric acid type A receptor family genes in patients with colon adenocarcinoma

In the present study, the significance of GABA_A genes in colon adenocarcinoma (COAD) were investigated from the view of diagnosis and prognosis. All data were achieved from The Cancer Genome Atlas. Overall survival was analyzed by the Kaplan-Meier analyses and Cox regression model and the hazard ratios and 95% confidence interval were calculated for computation. The Database for Annotation, Visualization and Integrated Discovery, and the Biological Networks Gene Ontology (BiNGO) softwares were applied to assess the biological processes and Kyoto Encyclopedia of Genes and Genomes (KEGG) was used for pathway analysis to predict the biological function of GABA_A genes. The associated Gene Ontology and KEGG pathways were conducted by Gene Set Enrichment Analysis (GSEA). From receiver operating characteristics curves analysis, it was found that the expression of GABR, γ-aminobutyric acid type A receptor GABRA2, GABRA3, GABRB2, GABRB3, GABRG2, GABRG3, GABRD, GABRE were correlated with COAD occurrence [P<0.0001, area under the curve (AUC)>0.7]. The low expression of the GABRB1, GABRD, GABRP and GABRQ in genes after tumor staging adjustment were positively correlated with the overall survival rate [P=0.049, hazard ratio (HR)=1.517, 95% confidence interval (CI)=1.001–2.297; P=0.006, HR=1.807, 95% CI=1.180–2.765; P=0.005, HR=1.833, 95% CI=1.196–2.810; P=0.034, HR=1.578, 95% CI=1.036–2.405). GSEA showed enrichment of cell matrix adhesion, integrin binding, angiogenesis, endothelial growth factor and endothelial migration regulation in patients with COAD with GABRD overexpression. GABRB1, GABRD, GABRP and GABRQ were associated with the prognostic factors of COAD. The expression levels of GABRA2, GABRA3, GABRB2, GABRB3, GABRG2, GABRD and GABRE may allow differentiation between tumor tissues and adjacent normal tissues.

Genetic advances in gout: potential applications in clinical practice

PURPOSE OF REVIEW

Many novel genetic associations in the field of hyperuricaemia and gout have been described recently. This review discusses advances in gout genetics and their potential clinical applications.

RECENT FINDINGS

Genome-wide association studies have identified approximately 30 serum urate-associated loci, some of which represent targets for drug development in gout. Some genes implicated in initiating the inflammatory response to deposited crystals in gout flares have also been described. In addition, genetic studies have been used to understand the link between hyperuricaemia and other comorbidities, particularly cardiometabolic diseases. ABCG2 has been established as a key genetic determinant in the onset of gout, and plays a role in the progression and severity of disease. Recent pharmacogenetic studies have also demonstrated the association between ABCG2 and poor response to allopurinol, and the link between HLA-B58:01 genotype and adverse drug reactions to allopurinol.

SUMMARY

Advances in gout genetics have provided important molecular insights into disease pathogenesis, better characterized the pharmacogenetics of allopurinol, and raised the possibility of using genetic testing to provide personalized treatment for patients. Prospective studies are now needed to clarify whether genetic testing in gout provides further benefit when added to established clinical management.

Integrative Genome-Wide Association Studies of eQTL and GWAS Data for Gout Disease Susceptibility

There is a paucity of genome-wide association study on Han Chinese gout patients. We performed a genome-wide association meta-analysis on two Taiwanese cohorts consisting of 758 gout cases and 14166 controls of Han Chinese ancestry. All the participants were recruited from the Taiwan Biobank. For pathway analysis, we applied ICSNPathway (Identify candidate Causal SNPs and Pathways) analysis, and to investigate whether expression-associated genetic variants contribute to gout susceptibility, we systematically integrated lymphoblastoid expression quantitative trait loci (eQTL) and genome-wide association data of gout using Sherlock, a Bayesian statistical frame-work. In the meta-analysis, we found 4 SNPs that reached genome-wide statistical significance (P < 5.0 × 10⁻⁸). These SNPs are in or close to ABCG2, PKD2 and NUDT9 gene on chromosome 4. ICSNPathway analysis identified rs2231142 as the candidate causal SNP, and ABCG2 as the candidate gene. Sherlcok analysis identified three genes, which were significantly associated with the risk of gout (PKD2, NUTD9, and NAP1L5). To conclude, we reported novel susceptible loci for gout that has not been previously addressed in the literature.

Polymorphisms of ABCG2 and its impact on clinical relevance

Human ABCG2 is one of the most important ATP-binding cassette (ABC) transporters. This protein functions as a xenobiotic transporter of large, hydrophobic, positively or negatively charged molecules, a wide variety anticancer drugs, fluorescent dyes, and different toxic compounds found in normal food. SNPs in ABCG2 may affect absorption and distribution of these substrates, altering the accumulation, effectiveness and toxicity of compounds or drugs in large populations. Its transport properties have been implicated clinically and ABCG2 expression is linked with different disease states. We reviewed the SNPs of ABCG2 in clinical relevance about gout, acute myeloid leukemia, solid tumors, and other diseases.

Genomic Influences on Hyperuricemia and Gout

Genome-wide association studies (GWAS) have identified nearly 30 loci associated with urate concentrations that also influence the subsequent risk of gout. The ABCG2 Q141 K variant is highly likely to be causal and results in internalization of ABCG2, which can be rescued by drugs. Three other GWAS loci contain uric acid transporter genes, which are also highly likely to be causal. However identification of causal genes at other urate loci is challenging. Finally, relatively little is known about the genetic control of progression from hyperuricemia to gout. Only 4 small GWAS have been published for gout.

Correlation of MCT1 and ABCC2 gene polymorphisms with valproic acid resistance in patients with epilepsy on valproic acid monotherapy

Valproic acid (VPA) is used as one of the first-line antiepileptic drugs to control seizure in epilepsy patients. However, one third of patients do not respond to VPA. This study is to investigate the influence of single nucleotide polymorphisms (SNPs) in multidrug transporters on VPA responses in Han Chinese epilepsy patients on VPA monotherapy. Twelve SNPs involved in VPA transport pathways, including ABCC2, ABCC4, ABCG2, MCT1, MCT2 and OATP2B1 were genotyped in 153 Han Chinese epilepsy patients. We found that among all the patients, MCT1 rs60844753 CC carriers have higher incidence of VPA-resistance than CG carriers (P = 0.05), and in subgroup of generalized seizure, ABCC2 rs3740066 CC carriers had higher frequency of VPA resistance than TC + TT carriers (P = 0.03). Although other SNPs were not correlated with VPA resistance, significant ethnic difference was found in minor allele frequency of these SNPs, indicating that the influence of these SNPs on VPA efficacy should be broadly investigated in other ethnic populations. This study provides nominal evidence that SNPs of genes involved in the transport of VPA contribute to interpatient variation in VPA response. Although the associations were abolished after Bonferroni correction, the results provide an incentive for further research in sufficiently large samples.

Variants of ALPK1 with ABCG2, SLC2A9, and SLC22A12 increased the positive predictive value for gout

We investigated the interactions of ALPK1 variants and the loci of ABCG2, SLC2A9, and SLC22A12 on gout risk. We conducted two case-control studies. Participants were recruited from hospitals (n = 410; 104 gout cases and 306 controls) and communities (n = 678; 373 gout cases and 305 controls) in Taiwan. The genotypes of ALPK1 (rs11726117 M861T, rs231247 R1084R, and rs231253 3' UTR), ABCG2 (rs2231142 Q141K and rs2231137 V12M), SLC2A9 (rs3733591 R265H and rs1014290), and SLC22A12 (rs3825016 H86H, rs11231825 H142H, and rs475688) were genotyped. Under a recessive model, the joint effects of ALPK1 variants and the SNPs rs2231142 of ABCG2, rs1014290 of SLC2A9, or rs475688 and rs3825016 of SLC22A12 were associated with gout. The rs11726117 [CC] of ALPK1 and rs2231142 [TT] of ABCG2 with the sequential addition of the rs1014290 [AA] of SLC2A9 and rs3825016 [CC] of SLC22A12 were associated with gout risk (odds ratio (OR): 13.01, 15.11, and 55.00 and positive predictive value (PPV): 56%, 69%, and 99% in the Han group, respectively; OR: 3.76, 5.78, and 12.30 and PPV: 74%, 80%, and 81% in the aboriginal group, respectively). Combined exposure to the four high-risk genotypes of ALPK1 and the uric-acid-related loci of ABCG2, SLC2A9, and SLC22A12 was associated with an increased gout risk and a high PPV for gout.

Functional non-synonymous variants of ABCG2 and gout risk

Objectives

Common dysfunctional variants of ATP binding cassette subfamily G member 2 (Junior blood group) (ABCG2), a high-capacity urate transporter gene, that result in decreased urate excretion are major causes of hyperuricemia and gout. In the present study, our objective was to determine the frequency and effect on gout of common and rare non-synonymous and other functional allelic variants in the ABCG2 gene.

Methods

The main cohort recruited from the Czech Republic consisted of 145 gout patients; 115 normouricaemic controls were used for comparison. We amplified, directly sequenced and analysed 15 ABCG2 exons. The associations between genetic variants and clinical phenotype were analysed using the t-test, Fisher's exact test and a logistic and linear regression approach. Data from a New Zealand Polynesian sample set and the UK Biobank were included for the p.V12M analysis.

Results

In the ABCG2 gene, 18 intronic (one dysfunctional splicing) and 11 exonic variants were detected: 9 were non-synonymous (2 common, 7 rare including 1 novel), namely p.V12M, p.Q141K, p.R147W, p.T153M, p.F373C, p.T434M, p.S476P, p.D620N and p.K360del. The p.Q141K (rs2231142) variant had a significantly higher minor allele frequency (0.23) in the gout patients compared with the European-origin population (0.09) and was significantly more common among gout patients than among normouricaemic controls (odds ratio = 3.26, P < 0.0001). Patients with non-synonymous allelic variants had an earlier onset of gout (42 vs 48 years, P = 0.0143) and a greater likelihood of a familial history of gout (41% vs 27%, odds ratio = 1.96, P = 0.053). In a meta-analysis p.V12M exerted a protective effect from gout (P < 0.0001).

Conclusion

Genetic variants of ABCG2, common and rare, increased the risk of gout. Non-synonymous allelic variants of ABCG2 had a significant effect on earlier onset of gout and the presence of a familial gout history. ABCG2 should thus be considered a common and significant risk factor for gout.

A comprehensive analysis of the association of common variants of ABCG2 with gout

The objective of the present study was to determine whether there was an association between single nucleotide polymorphisms (SNPs) in ABCG2 and gout. We recruited 333 participants including 210 patients with gout and 123 controls and genotyped 45 SNPs in both cohorts. We found that 24 SNPs in ABCG2 are susceptibility loci associated with gout. Haplotype analysis revealed five blocks across the ABCG2 locus were associated with an increased risk of gout with odds ratios (ORs) from 2.59–3.17 (all P < 0.0001). A novel finding in the present study was the identification of rs3114018 in block 3 and its association with increased gout risk. We found that the rs2231142T allele in block 2 and the rs3114018C-rs3109823T (C-T) risk haplotype in block 3 conferred the greatest evidence of association to gout risk (P = 1.19 × 10⁻¹² and P = 9.20 × 10⁻¹¹, respectively). Our study provides an improved understanding of ABCG2 variations in patients with gout and, as shown by haplotype analysis, that ABCG2 may have a role in gout susceptibility.

The genetics of gout: towards personalised medicine?

Over the last decade, there have been major advances in the understanding of the genetic basis of hyperuricaemia and gout as well as of the pharmacogenetics of urate-lowering therapy. Key findings include the reporting of 28 urate-associated loci, the discovery that ABCG2 plays a central role on extra-renal uric acid excretion, the identification of genes associated with development of gout in the context of hyperuricaemia, recognition that ABCG2 variants influence allopurinol response, and the impact of HLA-B*5801 testing in reducing the prevalence of allopurinol hypersensitivity in high-risk populations. These advances, together with the reducing cost of whole genome sequencing, mean that integrated personalised medicine approaches may soon be possible in clinical practice. Genetic data may inform assessment of disease prognosis in individuals with hyperuricaemia or established gout, personalised lifestyle advice, selection and dosing of urate-lowering therapy, and prevention of serious medication adverse effects. In this article, we summarise the discoveries from genome-wide association studies and discuss the potential for translation of these findings into clinical practice.

ABCG2 polymorphisms in gout: insights into disease susceptibility and treatment approaches

As a result of the association of a common polymorphism (rs2231142, Q141K) in the ATP-binding cassette G2 (ABCG2) transporter with serum urate concentration in a genome-wide association study, it was revealed that ABCG2 is an important uric acid transporter. This review discusses the relevance of ABCG2 polymorphisms in gout, possible etiological mechanisms, and treatment approaches. The 141K ABCG2 urate-increasing variant causes instability in the nucleotide-binding domain, leading to decreased surface expression and function. Trafficking of the protein to the cell membrane is altered, and instead, there is an increased ubiquitin-mediated proteasomal degradation of the variant protein as well as sequestration into aggresomes. In humans, this leads to decreased uric acid excretion through both the kidney and the gut with the potential for a subsequent compensatory increase in renal urinary excretion. Not only does the 141K polymorphism in ABCG2 lead to hyperuricemia through renal overload and renal underexcretion, but emerging evidence indicates that it also increases the risk of acute gout in the presence of hyperuricemia, early onset of gout, tophi formation, and a poor response to allopurinol. In addition, there is some evidence that ABCG2 dysfunction may promote renal dysfunction in chronic kidney disease patients, increase systemic inflammatory responses, and decrease cellular autophagic responses to stress. These results suggest multiple benefits in restoring ABCG2 function. It has been shown that decreased ABCG2 141K surface expression and function can be restored with colchicine and other small molecule correctors. However, caution should be exercised in any application of these approaches given the role of surface ABCG2 in drug resistance.

Genetic risk scores, sex and dietary factors interact to alter serum uric acid trajectory among African-American urban adults

Serum uric acid (SUA), a causative agent for gout among others, is affected by both genetic and dietary factors, perhaps differentially by sex. We evaluated cross-sectional (SUAbase) and longitudinal (SUArate) associations of SUA with a genetic risk score (GRS), diet and sex. We then tested the interactive effect of GRS, diet and sex on SUA. Longitudinal data on 766 African-American urban adults participating in the Healthy Aging in Neighborhood of Diversity across the Lifespan study were used. In all, three GRS for SUA were created from known SUA-associated SNP (GRSbase (n 12 SNP), GRSrate (n 3 SNP) and GRStotal (n 15 SNP)). Dietary factors included added sugar, total alcohol, red meat, total fish, legumes, dairy products, caffeine and vitamin C. Mixed-effects linear regression models were conducted. SUAbase was higher among men compared with that among women, and increased with GRStotal tertiles. SUArate was positively associated with legume intake in women (γ=+0·14; 95 % CI +0·06, +0·22, P=0·001) and inversely related to dairy product intake in both sexes combined (γ=-0·042; 95 % CI -0·075, -0·009), P=0·010). SUAbase was directly linked to alcohol consumption among women (γ=+0·154; 95 % CI +0·046, +0·262, P=0·005). GRSrate was linearly related to SUArate only among men. Legume consumption was also positively associated with SUArate within the GRStotal's lowest tertile. Among women, a synergistic interaction was observed between GRSrate and red meat intake in association with SUArate. Among men, a synergistic interaction between low vitamin C and genetic risk was found. In sum, sex-diet, sex-gene and gene-diet interactions were detected in determining SUA. Further similar studies are needed to replicate our findings.

Population-specific association between ABCG2 variants and tophaceous disease in people with gout

Background

Tophi contribute to musculoskeletal disability, joint damage and poor health-related quality of life in people with gout. The aim of this study was to examine the role of SLC2A9 and ABCG2 variants in tophaceous disease in people with gout.

Methods

Participants (n = 1778) with gout fulfilling the 1977 American Rheumatism Association (ARA) classification criteria, who were recruited from primary and secondary care, attended a detailed study visit. The presence of palpable tophi was recorded. SLC2A9 rs11942223, ABCG2 rs2231142 and ABCG2 rs10011796 were genotyped. Data were analysed according to tophus status.

Results

Compared to participants without tophi, those with tophi were older, had longer disease duration and higher serum creatinine, and were more likely to be of Māori or Pacific (Polynesian) ancestry. SLC2A9 rs11942223 was not associated with tophi. However, the risk alleles for both ABCG2 single nucleotide polymorphisms (SNPs) were present more frequently in those with tophi (OR (95% CI) 1.24 (1.02–1.51) for rs2231142 and 1.33 (1.01–1.74) for rs10011796, p < 0.05 for both). The effect of rs2231142 was limited to participants of Māori or Pacific ancestry (OR 1.50 (1.14–1.99), p = 0.004), with a significant effect observed in those of Western Polynesian ancestry only (OR 1.71 (1.07–2.72), p = 0.017). The rs10011796 risk allele was strongly associated with tophi in the Western Polynesian group (OR 3.76 (1.61–8.77), p = 0.002), but not in the Eastern Polynesian group (OR 0.87 (0.52–1.46), p = 0.60) nor in the non-Polynesian group (OR 1.16 (0.81–1.66), p = 0.32). The ABCG2 associations persisted in the Western Polynesian group after adjusting for serum urate, creatinine, and disease duration, and when including both ABCG2 variants in the regression models.

Conclusions

Variation in ABCG2 function may play a role in the development of tophaceous disease in some populations with high prevalence of severe gout.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1254-8) contains supplementary material, which is available to authorized users.

Alcohol-related diseases and alcohol dependence syndrome is associated with increased gout risk: A nationwide population-based cohort study

OBJECTIVE

Alcohol intake is strongly associated with hyperuricemia, which may cause gout. This study evaluated the risk of gout in patients with alcohol-related diseases and alcohol dependence syndrome.

METHODS

We used the Taiwan National Health Insurance Research Database (NHIRD) to conduct a nationwide population-based cohort study to assess the risk of gout and gout incidence in patients with alcohol-related diseases and alcohol dependence syndrome (as defined by the International Classification of Diseases, Ninth Revision). In the NHIRD records from 1998 to 2008, we identified 11,675 cases of alcohol-related diseases. The control group comprised 23,350 cases without alcohol-related diseases propensity score-matched (1 case: 2 controls) for age, age group, and sex.

RESULTS

The results revealed that alcohol-related diseases were significantly associated with gout risk (adjusted hazard ratio 1.88; P<0.0001). Of the alcohol-related disease cases, 34.1% of the patients had alcohol dependence syndrome (males 34.8%; females 32.4%), and alcohol dependence was independently associated with gout occurrence (relative risk [RR] 2.01; P<0.0001). Severe alcohol-dependent patients (who were also the heavy benzodiazepines users), were associated with an increased risk of gout (RR 1.71 to 4.21, P≤0.0182).

CONCLUSION

Physicians should be aware of the association between alcohol dependence syndrome and gout occurrence, and alcohol use assessment and measures to prevent alcohol dependence should be implemented in the integrative care for patients with gout.

Additive composite ABCG2, SLC2A9 and SLC22A12 scores of high-risk alleles with alcohol use modulate gout risk

The aim of the present study was to evaluate the contribution of urate transporter genes and alcohol use to the risk of gout/tophi. Eight variants of ABCG2, SLC2A9, SLC22A12, SLC22A11 and SLC17A3 were genotyped in male individuals in a case-control study with 157 gout (33% tophi), 106 asymptomatic hyperuricaemia and 295 control subjects from Taiwan. The multilocus profiles of the genetic risk scores for urate gene variants were used to evaluate the risk of asymptomatic hyperuricaemia, gout and tophi. ABCG2 Q141K (T), SLC2A9 rs1014290 (A) and SLC22A12 rs475688 (C) under an additive model and alcohol use independently predicted the risk of gout (respective odds ratio for each factor=2.48, 2.03, 1.95 and 2.48). The additive composite Q141K, rs1014290 and rs475688 scores of high-risk alleles were associated with gout risk (P<0.0001). We observed the supramultiplicative interaction effect of genetic urate scores and alcohol use on gout and tophi risk (P for interaction=0.0452, 0.0033). The synergistic effect of genetic urate score 5-6 and alcohol use indicates that these combined factors correlate with gout and tophi occurrence.

Gout: a review of nonmodifiable and modifiable risk factors

Gout is a common inflammatory arthritis triggered by the crystallization of uric acid within the joints. Gout affects millions worldwide and has an increasing prevalence. Recent research has been carried out to better qualify and quantify the risk factors predisposing individuals to gout. These can largely be broken into nonmodifiable risk factors, such as gender, age, race, and genetics, and modifiable risk factors, such as diet and lifestyle. Increasing knowledge of factors predisposing certain individuals to gout could potentially lead to improved preventive practices. This review summarizes the nonmodifiable and modifiable risk factors associated with development of gout.

Prevalence of gout with comorbidity aggregations in southern Taiwan

OBJECTIVE

Comorbidity is an important concern for chronic gout patients. We evaluated the relationship between comorbidity profiles and gout in Taiwan aborigines and Taiwanese Han.

METHODS

We used the claims data from the Taiwan national health insurance database for 2004 to 2006. Physician-diagnosed gout and comorbidities were coded using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). Total sampling from Pingtung County of southern Taiwan included 37,482 aborigines (gout cases, n=3906 and controls, n=33,576) and 37,451 Han (gout cases, n=1115 and controls, n=36,336).

RESULTS

In 2006, the gout prevalences were 10.42% and 2.98% (prevalence ratio [PR]=3.50) in the aborigines and Han general populations, respectively. The prevalences of uric acid nephrolithiasis and tophi were higher in aborigines (0.42% and 0.30%, respectively) than in Han (0.09% and 0.04%, respectively). When stratified by comorbidity status, the prevalences of gout were 4.49% and 27.34% in aborigines and 1.52% and 9.44% in Han (approximate PR=3.00). Similarly, the prevalence ratios of gout in the comorbidity group, compared with the non-comorbidity group, were 6.09 in aborigines and 6.23 in Han. Multivariate odds ratios [ORs] showed that hypercholesterolemia, hyperglyceridemia, essential hypertension and renal insufficiency were the common comorbidities of gout (OR≥1.63); heart failure exerted a significant effect only in aborigines (OR=1.55). For five comorbidity factors, patients with multiple comorbidities had higher gout prevalence (maximum OR=12.90).

CONCLUSION

Gout prevalence was higher in aborigines, both with and without comorbidities, than in Han. The comorbid diseases and comorbidity aggregations showed a substantial association with gout occurrence in both ethnicities.