Early-onset Gout Research Articles

Systematic Screening of Autosomal Dominant Tubulointerstitial Kidney Disease- MUC1 27dupC Pathogenic Variant through Exome Sequencing.

The MUC1 gene is associated with autosomal dominant tubulointerstitial kidney disease (ADTKD), leading to CKD. Current methods of sequencing, like exome sequencing, rarely detect MUC1 pathogenic variants because of the variable number of tandem repeats (VNTR) in MUC1 exon2. We demonstrated that combining fast read filtering with a sensitive VNTR genotyping strategy enables systematic screening of 27dupC pathogenic MUC1 variant from exome data. We initially validated our bioinformatics pipeline in a proof-of-concept cohort incorporating exome data from 33 participants with a known MUC1 pathogenic variant identified by Snapshot PCR and confirmed by 54 MUC1-negative individuals for negative control. We then retrospectively analyzed exome sequencing data from January 2019 to October 2023 from 3512 adult participants with nephropathy of unknown origin. Finally, we prospectively validated our pipeline in 825 additional participants enrolled from November 2023. SharkVNTyper accurately identified MUC1 variants in 32 out of 33 participants and excluded its presence in all the 54 negative controls in the proof-of-concept cohort (sensitivity of 97%, specificity of 100%). Integration of Shark tool with VNTyper significantly reduced running time from 6-12 hours to 5-10 minutes per sample, allowing both retrospective and prospective analysis. In the retrospective cohort, SharkVNTyper identified 23 additional positive cases that were not suspected clinically and had been missed in the initial exome analysis; 18 of these cases were confirmed as carrying the MUC1 27dupC mutation by low-throughput Snapshot PCR. In the prospective cohort of 825 CKD cases, systematic screening discovered 13 positive cases, with 12 confirmed by PCR. Overall, of 63 participants (1.4% of 4653) with molecularly confirmed ADTKD-MUC1, comprehensive diagnoses and descriptions of the disease were available for 24 participants. Median age of kidney failure was 50 years, 38% exhibited bilateral multiple kidney cysts, 8% had early-onset gout, and 58% had arterial hypertension. SharkVNTyper enables the analysis of highly repeated regions, such as the MUC1 VNTR, and facilitates the systematic screening of ADTKD-MUC1 from exome data, fostering 27dupC variation identification.

Elevated serum IL-2 and Th17/Treg imbalance are associated with gout

Gout is considered an auto-inflammatory disorder, and the immunological drivers have not been fully unraveled. This study compared the peripheral lymphocyte and CD4+T cell subsets, and cytokines in gout and healthy controls (HCs) to explore the contributions of T helper 17 (Th17) cells, T regulatory (Treg) cells and cytokines to the pathogenesis of gout. We enrolled 126 gout patients (53 early-onset gout with age of first presentation < 40 years, and 73 late-onset gout with age of first presentation ≥ 40 years) and 77 HCs. Percentage and absolute numbers of peripheral lymphocyte and CD4+T cell subpopulations in each group were detected by flow cytometry. The serum cytokine levels were determined by flow cytometric bead array. For circulating CD4+T cell subsets, Th17/Treg ratio was significantly higher in early-onset gout, late-onset gout and gout without tophus than HCs; Th17 cells were significantly elevated in early-onset gout and gout without tophus, while the percentage of Treg cells was significantly decreased in early-onset and late-onset gout. Additionally, gout patients had significantly higher cytokines levels (including IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ, and TNF-α) than HCs; IL-2 levels were positively correlated with Treg cells and negatively correlated with ESR. ROC analysis showed that disease duration, CRP and fibrinogen, had moderate predictive performances for tophus in gout (the AUCs were 0.753, 0.703 and 0.701, respectively). Our study suggests that early-onset and late-onset gout differ in Th17/Treg imbalance, which in early-onset gout is due to elevated Th17 cells and in late-onset gout is due to decreased Treg cells. And increased serum cytokine levels, especially IL-2, may play an essential role in that. Restoring Th17/Treg balance may be a crucial way to improve the prognosis of gout patients.

Comparison Between Early-Onset and Common Gout: A Systematic Literature Review.

Gout is an inflammatory, metabolic disease associated with a high comorbidity burden including cardiovascular disease, hypertension, type 2 diabetes, hyperlipidemia, renal disease, and metabolic syndrome. Approximately 9.2 million Americans have gout, making prognosis and treatment outcome predictors highly important. About 600,000 Americans have early-onset gout (EOG), generally defined as first gout attack at ≤ 40years of age. However, data on EOG clinical features, comorbidity profile, and treatment response are sparse; this systematic literature review provides insight. PubMed and American College of Rheumatology (ACR)/European Alliance of the Associations for Rheumatology (EULAR) abstract archives were searched for early-onset gout, "early onset gout," and ("gout" AND "age of onset"). Duplicate, foreign language, single case report, older (before 2016), and irrelevant/data insufficient publications were excluded. The age of diagnosis categorized patients as having common gout (CG, generally > 40years) or EOG (generally ≤ 40years). Applicable publications were extensively reviewed/discussed among authors for inclusion/exclusion consensus. A total of 283 publications were identified, with 46 (35 articles, 10 abstracts) reviewed and 17 (12 articles,5 abstracts) ultimately included. Eleven reported clinical characteristics, with 6 EOG-CG retrospective/cross-sectional comparisons. Gout diagnosis preceded cardiometabolic comorbidity and renal comorbidities were less prevalent in EOG than CG patients. EOG patients had more severe disease (more gout flares, polyarticular disease), higher pre-therapy serum urate (SU), and worse oral urate-lowering therapy response. Genetics-focused publications reported higher incidences of dysfunctional urate transporter mutations in EOG patients. This review suggests that EOG is more recalcitrant to urate-lowering therapy, is associated with urate transporter defects, and carries heavy disease burden. Therefore, early rheumatology referral and urate-lowering in a treat-to-target fashion may benefit EOG patients. Interestingly, EOG patients had fewer cardiometabolic comorbidities at diagnosis than CG patients, presenting a potential "window of opportunity" to attenuate cardiometabolic comorbidity development with SU control. Preventing gout-related suffering and health burden is particularly important in these young EOG patients who will live with gout and its sequelae for decades.

Early-onset gout and rare deficient variants of the lactate dehydrogenase D gene.

To investigate whether the lactate dehydrogenase D (LDHD) gene deficiency causes juvenile-onset gout. We used whole-exome sequencing for two families and a targeted gene-sequencing panel for an isolated patient. d-lactate dosages were analysed using ELISA. We demonstrated linkage of juvenile-onset gout to homozygous carriage of three rare distinct LDHD variants in three different ethnicities. In a Melanesian family, the variant was (NM_153486.3: c.206C>T; rs1035398551) and, as compared with non-homozygotes, homozygotes had higher hyperuricaemia (P = 0.02), lower fractional clearance of urate (P = 0.002), and higher levels of d-lactate in blood (P = 0.04) and urine (P = 0.06). In a second, Vietnamese, family, very severe juvenile-onset gout was linked to homozygote carriage of an undescribed LDHD variant (NM_153486.3: c.1363dupG) leading to a frameshift followed by a stop codon, p.(AlaGly432fsTer58). Finally, a Moroccan man, with early-onset and high d-lactaturia, whose family was unavailable for testing, was homozygous for another rare LDHD variant [NM_153486.3: c.752C>T, p.(Thr251Met)]. Rare, damaging LDHD variants can cause autosomal recessive early-onset gout, the diagnosis of which can be suspected by measuring high d-lactate levels in the blood and/or urine.

Update Gout

Update Gout Abstract. Gout, the most frequent arthritis worldwide, is seldomly considered a serious chronic disease. Cardiovascular morbidity and allover mortality are increased in gout patients. Prevalence of gout is very variable in different countries and is estimated to be 2.6% overall. Men are overrepresented (3:1 to 4:1). Environmental factors, such as diet and alcohol intake, are still important, but the genetic influence, e.g., in early-onset gout, gets more and more attention. Despite the broad range of therapeutic options outcomes are poor, and the disease often leads to disabling structural damages, not only in joints. Patients' education, and the involvement of trained general practitioners and nurses will hopefully improve the outcomes of this treatable disease.

Clustering Patients With Gout Based on Comorbidities and Biomarkers: A Cross-Sectional Study.

This single-center clinical study identifies clusters of different phenotypes and pathophysiology subtypes of patients with gout and associated comorbidities. Patients clinically diagnosed with gout were enrolled between January 2018 and December 2019. Hierarchical cluster analyses were performed using clinical data or biological markers, inflammatory markers, and oxidative stress pathway metabolites assayed from serum and plasma samples. Subgroup clusters were compared using ANOVA for continuous data and chi-square tests for categorical data. Hierarchical cluster analysis identified 3 clusters. Cluster 1 (C1; n = 24) comprised dyslipidemia, hypertension, and early-onset gout, without tophi. Cluster 2 (C2; n = 25) comprised hypertension, dyslipidemia, nephrolithiasis, and obesity. Cluster 3 (C3; n = 39) comprised multiple comorbidities and tophi. Post hoc comparisons of data obtained from samples of patients in C1, C2, and C3 revealed significant differences in the levels of oxidative stress and inflammation-related markers, including 3-nitrotyrosine, tumor necrosis factor, C-reactive protein, interleukin (IL) 1β, IL-6, platelet-derived growth factor (PDGF)-AA, and PDGF-BB. Reclustering patients based on all markers as well as on the biological markers that significantly differed among the initial clusters identified similar clusters. Oxidative stress and inflammatory marker levels may affect the development and clinical manifestations (ie, clinical phenotypes) of gout. Measuring oxidative stress and levels of inflammatory cytokines is a potential adjunctive tool and biomarker for early identification and management of gout.

Profiling of serum oxylipins identifies distinct spectrums and potential biomarkers in young people with very early onset gout.

Oxylipins modulate inflammation via complex pathways. The oxylipin profile in gout remains unexplored. In this study, we systemically profiled oxylipins in young men and identified new oxylipin biomarkers for clinical use in differentiating gout from hyperuricaemia. Oxylipin profiling was performed in 90 men (30 very early onset gout, 30 asymptomatic hyperuricaemia [HU] and 30 normouricaemia [NU], all aged <20 years) divided into discovery and validation sample sets. The dataset was analysed based on orthogonal projection to latent structure-discriminant analysis. Correlation network and pathway enrichment were conducted to reveal potential oxylipin-involved pathways of gout. Candidate oxylipins were further evaluated and optimized in the validation cohort, and differential oxylipin biomarkers combined with or without serum urate were applied to construct diagnostic models. In discovery stage, 21 differential oxylipins in the gout vs HU comparisons and 14 differential oxylipins in the gout vs NU comparisons were discovered. Correlation network analysis was performed and 14(S)-HDHA (14S-hydroxy-4Z,7Z,10Z,12E,16Z,19Z-docosahexaenoic acid) was identified as a hub metabolite in both comparisons. Seven down-regulated oxylipins in the gout vs HU group and five down-regulated oxylipins in the gout vs NU group were validated. Diagnostic models were constructed with the above oxylipins, with 14(S)-HDHA alone having an area under the curve of 1 (95% CI, 1, 1) in both comparisons. Young men with very early onset gout have distinct oxylipin spectrums, especially those derived from arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. Differential oxylipins could serve as candidate serum biomarkers in differentiating gout from hyperuricaemia.

MO030: Familial clustering of a rare UMOD variant in undiagnosed hereditary nephropathy suggests the presence of a common ancestral founder mutation

Abstract BACKGROUND AND AIMS ADTKD–UMOD (Autosomal dominant tubulointerstitial kidney disease–UMOD) is a rare genetic disease due to a heterozygous mutation in the UMOD gene encoding uromodulin. It is classically characterized by minimal proteinuria, slowly progressive CKD, hyperuricemia and early-onset gout. With increasing awareness and testing, pathogenic variants in UMOD are being identified more frequently although the nonspecific nature of most symptoms makes clinical diagnosis difficult. We report the surprising finding of a rare UMOD variant in 11 seemingly unrelated families referred to Sheffield or Nottingham renal genetics services over a 15-year period with undiagnosed hereditary kidney disease. METHOD The probands identified were initially referred to renal genetics services based in Sheffield and Nottingham between 2006 and 2021, where they underwent genetic testing and a comprehensive renal workup. All had a family history of ESRD. A pathogenic variant of UMOD, c.278_289delinsCCGCCTCCT was identified in 11 probands by gene or panel-based sequencing. Family members of the affected probands were invited for genetic testing and clinical follow-up. A retrospective review of all patients screened or with ESRD at both renal genetic clinics was conducted. Molecular modeling of the variant was performed using in-silico tools. RESULTS Clinical data from 60 members (11 pedigrees) was obtained. All individuals were born in the United Kingdom and of White British ethnicity. A total of 37 tested positive for the variant, 3 were negative and 19 were not tested due to being deceased (n = 13) and for unknown reasons (n = 6). The median age of ESRD was 52 (range 32, 76) years. More females had ESRD comprising 67% (20/30). Of patients with available data, 68% (30/44) had hypertension, 7.3% (3/41) had proteinuria &amp;gt;30 mg/g and 18% (7/40) had mild hematuria. A total of 11% (6/57) had experienced ≥1 episode of gout with a median onset of 42.5 (range 29–61) years. Only one patient had asymptomatic renal calculi. All patients with CKD who carried the UMOD mutation (n = 22) had hypertension, apart from two who had unknown hypertensive status (n = 1) or reflux nephropathy causing kidney scarring (n = 1). Renal histology where available (8) showed glomerulosclerosis and tubulointerstitial fibrosis. Ultrasound kidney lengths were normal or reduced and renal cysts were only occasionally detected. Molecular modeling of the variant showed structural changes in the cysteine-rich (C6) with EGFII-like Ca2+ binding domain of UMOD, predicted to disrupt disulfide-bond formation (fifth cysteine C94–sixth cysteine C106) as well as by altering the loop (93–97) between two β-sheets of EGFII domain (AlphaFold), possibly altering calcium ion binding (DeepFRI). This variant was initially reported as a recurrent mutation in four apparently unrelated families [1] and has since been noted in a further 11 families [2], all of White British ethnicity. CONCLUSION We have identified a rare pathogenic UMOD variant shared by 11 apparently unrelated families with familial ESRD within a contiguous geographical region of England. The nonspecific symptoms associated with this variant (especially the rarity of gout) were atypical from those with more classical UMOD variants leading to a delay in diagnosis. Our findings and those of others suggest that this is likely to represent a common ancestral variant rather than a recurrent variant within the UK population. 1. Smith GD, Robinson C, Stewart AP et al. Characterization of a recurrent in-frame UMOD indel mutation causing late-onset autosomal dominant end-stage renal failure. Clin J Am Soc Nephrol 2011; 6: 2766–2774. 2. Kidd K, Vylet'al P, Schaeffer C et al. Genetic and clinical predictors of age of ESKD in individuals with autosomal dominant tubulointerstitial kidney disease due to UMOD mutations. Kidney Int Rep 2020; 5:1472–1485.

Exome Sequencing Identifying LRP2 Gene (rs2228171) Related Hyperuricemia in Thai Patients with Non-communicable Diseases

Background: Although genome-wide association studies have been conducted to investigate the association between genomic loci associated with urate concentrations and gout in a large population. However, there is a lack of information in the Thai population. Objective: To identify the new genetic predisposition of hyperuricemia (HUA) and gout in non-communicable disease patients (NCDs). Materials and Methods: A whole-genome sequencing (WGS) using the Illumina HiSeq X Ten platform (Macrogen, Korea) was performed on the genomic DNA of 4 adult men (HUA, gout, early-onset gout, and normal subjects) who selected from 250 individuals of Gout among Thai Population Study. Then the candidate gene was identified the association of HUA in Thai NCDs patients (n=550). Results: The data set comprised 118,599 single-nucleotide variants were selected in all 4 participants. The missense Ala17Thr (G&gt;A) GLUT9 mutation was found only in early-onset gout. The synonymous Pro1146Pro, A&gt;G RREB1 mutation was identified in HUA and gout. WGS also identified synonymous Ile223Ile (C&gt;T) ABCC4) and non-synonymous Ala2872Thr (G&gt;A) LRP2 mutation in patients with HUA, early-onset gout, and gout. Because a missense of LRP2 (rs2228171) was found in the HUA subject. Thus the frequencies and association of rs2228171 in patients with HUA, hypertension, diabetes mellitus, heart disease, obesity, dyslipidemia, and stroke by using polymerase chain reaction and DNA sequencing analysis were investigated. Seventy-eight of 550 NCDs patients were selected. As result, an association between LRP2 and HUA was not found. The genotypes GA (adjusted OR 0.11, p=0.040), AA (adjusted OR 0.05, p=0.017) were associated with hypertension. However, the effect of rs2228171 in hypertension was still controversial due to the small population. Conclusion: Our study is the first cross-sectional study of the rs2228171 related HUA in Thai NCDs patients. Furthermore, the study will be done to clarify the effect of rs2228171 and metabolic diseases such as hypertension. Keywords: LRP2 rs2228171, Serum uric acid levels, Non-communicable disease, Single nucleotide polymorphism

The Role of ABCG2 in the Pathogenesis of Primary Hyperuricemia and Gout-An Update.

Urate homeostasis in humans is a complex and highly heritable process that involves i.e., metabolic urate biosynthesis, renal urate reabsorption, as well as renal and extrarenal urate excretion. Importantly, disturbances in urate excretion are a common cause of hyperuricemia and gout. The majority of urate is eliminated by glomerular filtration in the kidney followed by an, as yet, not fully elucidated interplay of multiple transporters involved in the reabsorption or excretion of urate in the succeeding segments of the nephron. In this context, genome-wide association studies and subsequent functional analyses have identified the ATP-binding cassette (ABC) transporter ABCG2 as an important urate transporter and have highlighted the role of single nucleotide polymorphisms (SNPs) in the pathogenesis of reduced cellular urate efflux, hyperuricemia, and early-onset gout. Recent publications also suggest that ABCG2 is particularly involved in intestinal urate elimination and thus may represent an interesting new target for pharmacotherapeutic intervention in hyperuricemia and gout. In this review, we specifically address the involvement of ABCG2 in renal and extrarenal urate elimination. In addition, we will shed light on newly identified polymorphisms in ABCG2 associated with early-onset gout.

Identification of Two Dysfunctional Variants in the ABCG2 Urate Transporter Associated with Pediatric-Onset of Familial Hyperuricemia and Early-Onset Gout.

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.

Early onset gout and chronic kidney disease in a young female patient.

Early onset gout and chronic kidney disease in a young female patient.

Trends in the manifestations of 9754 gout patients in a Chinese clinical center: A 10-year observational study.

The prevalence of gout is increasing but studies of its clinical features in large samples are lacking. This study aimed to clarify changes in the clinical manifestations of gout in China over the last decade and investigate the clinical features and risk factors of early-onset gout. Clinical manifestations were compared between 9754 gout patients who first presented at our clinic with gout in 2008-2012 (earlier group) or 2013-2018 (later group). Gout onset≤30 years old was defined as early-onset and>30 years as late-onset. Clinical features and risk factors were compared between the groups. The gout-onset age was 4.14 years younger and the percentage of early-onset gout (3827 patients) was higher in the later 2013-2018 group (5979 patients). The disease duration was significantly shorter (5.72±0.09 vs. 6.01±0.11 years P < 0,05) and the ratio of patients with tophi was correspondingly lower in the later group (22.0% vs. 20.0%, P < 0,05). More patients were obese (32.6% vs. 37.7%, P<0.001) and serum urate levels (465.0±1.9μmol/L vs. 485.5±1.5μmol/L) were significantly higher in the later group. As the age of gout-onset became younger, we did the multivariate logistic regression and identified a positive family history, male sex, obesity, elevated serum urate, and sugar-sweetened soft drinks as independent predictors of early-onset gout. The manifestations of gout in China have changed over the last decade, associated with a trend towards younger onset.

The prevalence of the gout-associated polymorphism rs2231142 G>T in ABCG2 in a pregnant female Filipino cohort.

Gout is a metabolic disorder and one of the most common arthritic conditions. Hyperuricemia is the hallmark of developing gout and mostly caused by uric acid underexcretion. Gout disproportionately affects people of specific races and ethnicities. Filipinos are the second-largest Asian population in the USA and reported to have a higher prevalence of gout and hyperuricemia than non-Filipino counterparts and Filipinos residing in the Philippines. The genetic polymorphism rs2231142 G>T in the ABCG2 has been strongly associated with hyperuricemia and gout across multiple populations. However, the prevalence of this variant in Filipinos is unknown. Therefore, assessing the prevalence of this variant may provide insights on the high prevalence of hyperuricemia and gout in Filipinos. A total of 190 DNA samples from pregnant females who self-identified as a Filipino from the Hawaii Biorepository Bank were genotyped for rs2231142 G>T in the ABCG2. The prevalence of the gout risk allele (T) (46%) was significantly higher in Filipinos than in samples of Caucasians (12%, p < 0.001), Han Chinese (29%, p = 0.014), and African Americans (3%, p < 0.001). Similarly, the prevalence of the gout-risk genotype (TT) (21%) was significantly higher in Filipinos than in samples of Caucasians (1%, p < 0.001), Han Chinese (9%, p = 0.002), and African Americans (0.1%, p < 0.001). Though there were no gout cases in this cohort, these findings are suggestive of a genetic basis to the high prevalence of hyperuricemia and gout in Filipinos. This might also explain the reported reduced urinary uric acid excretion in Filipinos compared with Caucasians. Key Points • The Filipinos have the highest prevalence of the gout-associated risk allele (T) of the rs2231142 G>T in ABCG2. • The high prevalence of the risk allele (T) of the rs2231142 G>T in ABCG2 may partly explain the reduced urinary urate excretion and early-onset gout in Filipinos. • The high prevalence of the risk allele (T) of the rs2231142 G > T in ABCG2 may predispose Filipinos to hyperuricemia and gout when acculturated to high-purine diet.

ABCG2 SNP associated with early-onset gout

ABCG2 SNP associated with early-onset gout

Systematic genetic analysis of early-onset gout: ABCG2 is the only associated locus

The aim of this study was to examine whether serum urate-associated genetic variants are associated with early-onset gout. Participants with gout in the Genetics of Gout in Aotearoa study with available genotyping were included (n = 1648). Early-onset gout was defined as the first presentation of gout <40 years of age. Single nucleotide polymorphisms (SNPs) for the 10 loci most strongly associated with serum urate were genotyped. Allelic association of the SNPs with early-onset gout was tested using logistic regression in an unadjusted model and in a model adjusted for sex, body mass index, tophus presence, flare frequency, serum creatinine and highest serum urate. The analysis was also done in two replication cohorts: Eurogout (n = 704) and Ardea (n = 755), and data were meta-analysed. In the Genetics of Gout in Aotearoa study, there were 638 (42.4%) participants with early-onset gout. The ABCG2 rs2231142 gout risk T-allele was present more frequently in participants with early-onset gout compared with the later-onset group. For the other SNPs tested, no differences in risk allele number were observed. In the allelic association analysis, the ABCG2 rs2231142 T-allele was associated with early-onset gout in unadjusted and adjusted models. Analysis of the replication cohorts confirmed the association of early-onset gout with the ABCG2 rs2231142 T-allele, but not with other serum urate-associated SNPs. In the meta-analysis, the odds ratio (95% CI) for early-onset gout for the ABCG2 rs2231142 T-allele was 1.60 (1.41, 1.83). In contrast to other serum urate-raising variants, the ABCG2 rs2231142 T-allele is strongly associated with early-onset gout.

Clinical Characteristics of Early-Onset Gout in Outpatient Setting.

ObjectiveThe objective of this study is to investigate the clinical characteristics and treatment of patients with early‐onset gout.MethodsWe retrospectively reviewed 327 adult patients with a first diagnosis of gout from 2008 to 2016 using the database of a multispecialty group practice in New England. Patients were classified into the following groups: age 30 years or younger at first diagnosis (group 1), age 31‐40 years (group 2), and age over 40 years (group 3). The clinical characteristics and treatment of gout were compared among the three groups.ResultsWe identified 87 patients in group 1 and 140 patients in group 2. Group 3 included 100 patients randomly chosen from the 7216 patients with a first diagnosis at age over 40 years. Patients within group 1 had significantly higher serum uric acid (sUA) levels at the time of diagnosis and a more prominent family history of gout. Younger patients (groups 1 and 2) had a significantly higher body mass index than patients over 40 years of age (group 3). A substantial number of younger patients also had hypertension or hyperlipidemia. The majority of younger patients met the 2012 American College of Rheumatology (ACR) guidelines for initiating urate‐lowering therapy (ULT) on the basis of frequency of gout attacks, whereas the majority of patients over 40 years of age met the guidelines for ULT on the basis of chronic kidney disease. Patients over 40 years of age were more likely to achieve an sUA level less than 6.0 mg/dl.ConclusionPatients with a first diagnosis of gout at age 40 years or younger frequently had cardiovascular risk factors and were less likely to achieve an sUA level less than 6.0 mg/dl compared with patients over 40 years of age who were treated in routine clinical practice. Clinicians should be aware that patients with early‐onset gout may be an undertreated population with poor adherence to ULT and increased risk of recurrent gout and cardiovascular diseases.

A novel uromodulin mutation in autosomal dominant tubulointerstitial kidney disease: a pedigree-based study and literature review

Autosomal dominant tubulointerstitial kidney disease caused by mutations in uromodulin gene (ADTKD-UMOD) is a spectrum of hereditary renal disorders, characterized by early-onset hyperuricemia, gout and progressive nephropathy. This study presented a novel UMOD mutation in an ADTKD pedigree and reviewed studies in Chinese population. The index patient is a 16-year-old girl with hypertension, hyperuricemia and normal serum creatinine level. Four affected and six unaffected members were available for genetic screen. The mutation analysis was performed by next-generation sequencing and direct sequencing. A literature research was conducted to review Chinese ADTKD-UMOD cases. MEDLINE and Chinese Biomedicine Databases were searched with ‘uromodulin’, ‘juvenile gout’ and their related terms. Genetic sequencing revealed a de novo mutation within exon 3 (Cys223Gly), which was co-segregating with phenotype in this pedigree. In the review, four studies and our study involving a total of 67 ADTKD patients from 11 families were identified. Of these patients, 27 were confirmed to carry UMOD mutations. Mutations occurred in exon 3 were commonly observed, while mutations within exon 4, 5 and 9 occurred less frequently in Chinese ADTKD-UMOD cases. Among these cases, median age of symptom onset was 26.5 years, median age of end-stage renal diseases (ESRD) or death by ESRD was 41.9 years without renal replacement treatment. Phenotype caused by mutations in D8C domain seemed to be severe than those in GPI domain. Compared with patients of other race, Chinese ADTKD-UMOD patients advanced more aggressively to ESRD.

Illness Perceptions and Mortality in Patients With Gout: A Prospective Observational Study.

To examine whether illness perceptions independently predict mortality in early-onset gout. Between December 2006 and January 2014, a total of 295 participants with early-onset gout (<10 years) were recruited in Auckland and Wellington, New Zealand. The participants were followed up until February 2015, and mortality information was collected. Participants with complete data were included in the current study (n = 242). Cox proportional hazards models were used to examine the association between illness perceptions and mortality risk, after adjustment for covariates associated with disease severity and mortality in gout. In a Cox proportional hazards model adjusted for predictors of disease severity and mortality in gout (number of tophi, serum urate level, and frequency of flares), consequence beliefs, identity beliefs, concern beliefs, and emotional response to gout were associated with all-cause mortality (hazard ratios [HRs] 1.29, 1.15, 1.18, and 1.19, respectively; P < 0.05 for all). In the fully saturated model, the association between consequence beliefs and mortality remained robust after additional adjustment for ethnicity, disease duration, diuretic use, serum creatinine, and pain score (HR 1.18 [95% confidence interval 1.02-1.37]; P = 0.029). Negative beliefs about the impact of gout and severity of symptoms, as well as concerns about gout and the emotional response to gout, were independently associated with all-cause mortality. Illness perceptions are important and potentially modifiable risk factors to target in future interventions.

Clinical characteristics of early- and late-onset gout: A cross-sectional observational study from a Chinese gout clinic.

A retrospective cross-sectional study using data from an outpatient clinic in China was conducted to investigate the clinical features of early-onset gout patients.All patients diagnosed with gout were asked about clinical characteristics of their gout and comorbid diseases. Patients presenting with acute flares were asked about common triggers before the flare. "Early-onset" gout was defined as onset of gout before 40 years and "late-onset" as onset ≥40 years. Major joint involvement, flare frequency before presentation, the cumulative number of involved joints, proportions of tophi complications at presentation, flare triggers, as well as any metabolic, cardiovascular, cerebrovascular, and renal comorbidities, were compared between the 2 groups.A total of 778 gout patients were enrolled in this study, including 449 (57.7%) in the early-onset group and 329 (42.3%) in the late-onset group. Compared with the late-onset gout patients, the early-onset gout patients had a higher proportion of ankle/mid-foot involvement (62.8% vs 48.2%, P < 0.001), more frequent flares before presentation (11.2 ± 1.17 vs 6.97 ± 1.03 times per year, P = 0.01), higher cumulative number of involved joints (5.2 ± 0.26 vs 3.8 ± 0.26, P < 0.001), and more likely to have alcohol consumption as a flare trigger (65.2% vs 53.9%, P = 0.03); whereas early-onset gout patients had fewer metabolic, cardiovascular, cerebrovascular, or renal complications.Early- and late-onset gout patients had different clinical features. Early-onset seems to be influenced more by lifestyle, while late-onset patients have more complications because of comorbidities.