Emi Morita

Genome-wide association study of clinically defined gout identifies multiple risk loci and its association with clinical subtypes

Objective Gout, caused by hyperuricaemia, is a multifactorial disease. Although genome-wide association studies (GWASs) of gout have been reported, they included self-reported gout cases in which clinical information was insufficient. Therefore, the relationship between genetic variation and clinical subtypes of gout remains unclear. Here, we first performed a GWAS of clinically defined gout cases only. Methods A GWAS was conducted with 945 patients with clinically defined gout and 1213 controls in a Japanese male population, followed by replication study of 1048 clinically defined cases and 1334 controls. Results Five gout susceptibility loci were identified at the genome-wide significance level (p<5.0×10−8), which contained well-known urate transporter genes (ABCG2 and SLC2A9) and additional genes: rs1260326 (p=1.9×10−12; OR=1.36) of GCKR (a gene for glucose and lipid metabolism), rs2188380 (p=1.6×10−23; OR=1.75) of MYL2-CUX2 (genes associated with cholesterol and diabetes mellitus) and rs4073582 (p=6.4×10−9; OR=1.66) of CNIH-2 (a gene for regulation of glutamate signalling). The latter two are identified as novel gout loci. Furthermore, among the identified single-nucleotide polymorphisms (SNPs), we demonstrated that the SNPs of ABCG2 and SLC2A9 were differentially associated with types of gout and clinical parameters underlying specific subtypes (renal underexcretion type and renal overload type). The effect of the risk allele of each SNP on clinical parameters showed significant linear relationships with the ratio of the case–control ORs for two distinct types of gout (r=0.96 [p=4.8×10−4] for urate clearance and r=0.96 [p=5.0×10−4] for urinary urate excretion). Conclusions Our findings provide clues to better understand the pathogenesis of gout and will be useful for development of companion diagnostics.

Pro-/anti-inflammatory cytokine gene polymorphisms and chronic kidney disease: a cross-sectional study

BackgroundThe aim of this study was to explore the associations between common potential functional promoter polymorphisms in pro-/anti-inflammatory cytokine genes and kidney function/chronic kidney disease (CKD) prevalence in a large Japanese population.MethodsA total of 3,323 subjects aged 35-69 were genotyped for all 10 single nucleotide polymorphisms (SNPs) in the promoter regions of candidate genes with minor allele frequencies of > 0.100 in Japanese populations. The estimated glomerular filtration rate (eGFR) and CKD prevalence (eGFR < 60 ml/min/1.73 m2) of the subjects were compared among the genotypes.ResultsA higher eGFR and lower prevalence of CKD were observed for the homozygous variants of IL4 -33CC (high IL-4 [anti-inflammatory cytokine]-producing genotype) and IL6 -572GG (low IL-6 [pro-inflammatory cytokine]-producing genotype). Subjects with IL4 CC + IL6 GG showed the highest mean eGFR (79.1 ml/min/1.73 m2) and lowest CKD prevalence (0.0%), while subjects carrying IL4 TT + IL6 CC showed the lowest mean eGFR (73.4 ml/min/1.73 m2) and highest CKD prevalence (17.9%).ConclusionsThe functional promoter polymorphisms IL4 T-33C (rs2070874) and IL6 C-572G (rs1800796), which are the only SNPs that affect the IL-4 and IL-6 levels in Japanese subjects, were associated with kidney function and CKD prevalence in a large Japanese population.

A before and after comparison of the effects of forest walking on the sleep of a community-based sample of people with sleep complaints.

BackgroundSleep disturbance is a major health issue in Japan. This before-after study aimed to evaluate the immediate effects of forest walking in a community-based population with sleep complaints.MethodsParticipants were 71 healthy volunteers (43 men and 28 women). Two-hour forest-walking sessions were conducted on 8 different weekend days from September through December 2005. Sleep conditions were compared between the nights before and after walking in a forest by self-administered questionnaire and actigraphy data.ResultsTwo hours of forest walking improved sleep characteristics; impacting actual sleep time, immobile minutes, self-rated depth of sleep, and sleep quality. Mean actual sleep time estimated by actigraphy on the night after forest walking was 419.8 ± 128.7 (S.D.) minutes whereas that the night before was 365.9 ± 89.4 minutes (n = 42). Forest walking in the afternoon improved actual sleep time and immobile minutes compared with forest walking in the forenoon. Mean actual sleep times did not increase after forenoon walks (n = 26) (the night before and after forenoon walks, 380.0 ± 99.6 and 385.6 ± 101.7 minutes, respectively), whereas afternoon walks (n = 16) increased mean actual sleep times from 342.9 ± 66.2 to 475.4 ± 150.5 minutes. The trend of mean immobile minutes was similar to the abovementioned trend of mean actual sleep times.ConclusionsForest walking improved nocturnal sleep conditions for individuals with sleep complaints, possibly as a result of exercise and emotional improvement. Furthermore, extension of sleep duration was greater after an afternoon walk compared to a forenoon walk. Further study of a forest-walking program in a randomized controlled trial is warranted to clarify its effect on people with insomnia.

Significant interaction between LRP2 rs2544390 in intron 1 and alcohol drinking for serum uric acid levels among a Japanese population

A genome-wide association study identified that LRP2 rs2544390 in intron 1 was associated with serum uric acid (SUA) levels among Japanese, as well as polymorphisms of SLC22A12, ABCG2, and SLC2A9. This study aimed to confirm the association of rs2544390 C/T with SUA, as well as another LRP2 polymorphism (rs3755166 G/A) in the promoter. Subjects were 5016 health checkup examinees (3409 males and 1607 females) aged 35 to 69years with creatinine<2.0mg/dL. The subjects with SLC22A12 258WW, SLC2A9 rs11722228C allele, ABCG2 126QQ and 141Q allele (2546 males and 1199 females) were selected for analysis. Mean SUA was 6.03mg/dL for CC, 6.18mg/dL for CT, and 6.19mg/dL for TT among males (p=0.012), and 4.49mg/dL, 4.45mg/dL, and 4.42mg/dL among females (not significant), respectively. No association was observed for rs3755166. The association with rs2544390 was stronger among male drinkers. The odds ratio of drinking ≥5/week relative to no drinking for hyperuricemia (SUA≥7mg/dL and/or under medication for hyperuricemia) was 1.11 (95% confidence interval, 0.67-1.84) among CC males, 1.75 (1.22-2.51) among CT males, and 3.13 (1.80-5.43) among TT males. The interaction terms with drinking ≥5/week were 1.56 (p=0.156) for CT and 2.87 (p=0.005) for TT. This was the first report on the interaction between LRP2 genotype and alcohol drinking for SUA. Since the low density lipoprotein-related protein 2 (megalin) encoded by LRP2 is a multi-ligand endocytic receptor expressed in many tissues including the kidney proximal tubules, the association/interaction remained to be confirmed both epidemiologically and biologically.

Significant association of serum uric acid levels with SLC2A9 rs11722228 among a Japanese population

Genome-wide association studies identified that SLC2A9 (GLUT9) gene polymorphisms were associated with serum uric acid (SUA) levels. Among the Japanese, a C/T polymorphism in intron 8 (rs11722228) was reported to be highly significant, though the function and strength of association were unknown. This study aimed to confirm the association, estimating the means of SUA according to the genotype, as well as OR of the genotype. Subjects were 5024 health checkup examinees (3413 males and 1611 females) aged 35 to 69 years with creatinine <2.0 mg/dL. Since SLC22A12 258X allele and ABCG2 126X allele are known to influence SUA levels strongly, the subjects with SLC22A12 258WW and ABCG2 126QQ (3082 males and 1453 females, in total 4535 subjects) were selected. The genotype frequency of SLC2A9 rs11722228 was 2184 for CC, 1947 for CT, and 404 for TT, being in Hardy-Weinberg equilibrium (p=0.312). Mean SUA was 6.10 mg/dL for CC, 6.25 mg/dL for CT, and 6.45 mg/dL for TT among males (p=1.5E-6), and 4.34 mg/dL, 4.59 mg/dL, and 4.87 mg/dL among females (p=4.6E-11), respectively. Males with SUA less than 5.0 mg/dL were 14.7% for CC, 10.6% for CT, and 7.8% for TT (p=2.3E-4), and females with SUA less than 4.0 mg/dL were 34.1%, 25.5%, and 15.4% (p=3.7E-6), respectively. This study was the first report to estimate the impact of SLC2A9 rs11722228 on SUA levels. Since the allele frequency of rs11722228 is similar among different ethnic groups, the impact remains to be examined in other ethnic groups.

PRKCH gene polymorphism is associated with the risk of severe gastric atrophy

BackgroundIndividuals infected with Helicobacter pylori do not necessarily develop gastric atrophy (GA) and gastric cancer (GC). Several factors, including genetic polymorphism, can regulate the development of GA and GC. A G/A single nucleotide polymorphism (rs3783799) of the PRKCH gene, which encodes the η isozyme of protein kinase C (PKCη), has been reported to be a tag single nucleotide polymorphism (SNP) of the PRKCH gene linked to a functional 1425G/A SNP in exon 9 (rs2230500). To elucidate its applicability in the development of GA and GC, this study aimed to investigate the associations of the PRKCH polymorphism with the risks of GA and GC.MethodsThe subjects consisted of 583 patients (cases) from first-visit outpatients at Aichi Cancer Center Hospital, aged 27 to 80 years, who were diagnosed as having GC from 2001 to 2005, and 1742 controls, frequency-matched for age and sex. Anti-H. pylori IgG antibodies and pepsinogens (PGs) in serum were measured for 1638 controls.ResultsOf the 1638 controls, 57.3% were seropositive and 33.0% had GA (PG1 ≤ 70 ng/dl and PG1/PG2 ≤ 3). When compared to the seronegative controls without GA, the AA genotype was significantly associated with severe GA (PG1 ≤ 30 ng/dl and PG1/PG2 ≤ 2); odds ratio (OR), 2.37 (95% confidence interval, 1.11–5.05) relative to the GG genotype. The genotype was not associated with the risk of GC.ConclusionThis was the first study to examine the associations of the PRKCH polymorphism with GA and GC, and suggested that the AA genotype, relative to the G/G genotype, may be a higher risk genotype for severe GA.

Renal hyperfiltration in prediabetes confirmed by fasting plasma glucose and hemoglobin A1c.

Background: The aim of the study was to confirm that glomerular hyperfiltration, an early and reversible stage of kidney damage, is associated in patients with prediabetes and prehypertension. Methods: In total, 5003 people aged between 35 and 69 years who had participated in the Shizuoka part of the Japan Multi-Institutional Collaborative Cohort (J-MICC) study took part in the study. Prevalence of hyperfiltration [the estimated glomerular filtration rate (eGFR) above the age- /sex-specific 95th percentile] was compared among different stages of prediabetes [fasting plasma glucose (FPG) < 100, 100–109, 110–125, and ≥126 mg/dL; and/or hemoglobin A1c (HbA1c) < 5.7, 5.7–6.0, 6.1–6.4 and ≥6.5% for no prediabetes, stage 1 prediabetes, stage 2 prediabetes, and overt diabetes, respectively] and prehypertension (blood pressure <120/80, 120–129/80–84, 130–139/85–89, and ≥140/90 mmHg for no prehypertension, stage 1 prehypertension, stage 2 prehypertension, and overt hypertension, respectively). Results: The prevalence of hyperfiltration increased with increasing stages of prediabetes (odds ratios: 1.25, 1.68, and 2.37 using FPG, and 1.26, 2.15, and 2.45 using HbA1c for stage 1 prediabetes, stage 2 prediabetes, and diabetes, respectively, relative to no prediabetes). Prehypertension, however, was not associated with hyperfiltration. Conclusion: The results confirmed that the prevalence of glomerular hyperfiltration increased with increasing stages (i.e., worsening) of prediabetes. Because both FPG and HbA1c showed similar association with hyperfiltration, either of these can be used to identify subjects who are at increased risk of nephropathy. Therefore, the functioning of kidneys should be monitored in subjects with prediabetes. Prompt treatment of hyperglycemia is necessary in subjects with hyperfiltration to prevent it to cause nephropathy.

Effect of the PPARG2 Pro12Ala polymorphism and clinical risk factors for diabetes mellitus on HbA1c in the Japanese general population.

Background Although the peroxisome proliferator-activated receptor-γ2 (PPARG2) Pro12Ala gene variant is associated with diabetes mellitus, the associations and interactions of this polymorphism and known clinical risk factors with glycated hemoglobin (HbA1c) remain poorly understood. We investigated if carrying the Ala allele was inversely associated with HbA1c level and examined possible interactions. Methods This cross-sectional analysis used data collected from 1281 men and 1356 women aged 40 to 69 years who completed the baseline survey of the Japan Multi-Institutional Collaborative Cohort Study. PPARG2 polymorphism was determined by multiplex polymerase chain reaction (PCR)-based Invader assay. Multiple linear regression and ANCOVA were used to control for confounding variables (age, body mass index [BMI], energy intake, alcohol, smoking, physical activity, and family history of diabetes) and examine possible interactions. Results After adjustment, the Ala allele was significantly inversely associated with HbA1c in women but not in men. Older age, BMI, and family history of diabetes were associated with higher HbA1c in both sexes. When stratified by PPARG2 genotype, these associations were observed in subjects with the Pro12Pro genotype but not in Ala allele carriers. A significant interaction of genotype and BMI on HbA1c was observed in women. Older age, BMI, and family history of diabetes were significantly associated with high-normal HbA1c (≥5.7% NGSP), whereas PPARG2 polymorphism was not. Conclusions Although PPARG2 Pro12Ala polymorphism might attenuate associations between known risk factors and HbA1c level, it had a small effect on high-normal HbA1c, as compared with clinical risk factors, in the general population.

Polymorphisms in genes encoding antioxidant enzymes (SOD2, CAT, GPx, TXNRD, SEPP1, SEP15 and SELS) and risk of chronic kidney disease in Japanese - cross-sectional data from the J-MICC study

Chronic kidney disease (CKD) is well known as a strong risk factor for both of end-stage renal disease and cardiovascular disease. To clarify the association of polymorphisms in the genes encoding antioxidant enzymes (SOD2, CAT, GPx, TXNRD, SEPP1, SEP15 and SELS) with the risk of CKD in Japanese, we examined this association using the cross-sectional data of Japan Multi-Institutional Collaborative Cohort (J-MICC) Study. The subjects were 3,285 men and women, aged 35–69 years, selected from J-MICC Study participants for whom genotyping were conducted by multiplex polymerase chain reaction-based Invader assay. The prevalence of CKD was determined for CKD stages 3–5 (eGFR <60 ml/min/1.73 m2). When those with CAT C-262T C/C were defined as reference, those with CAT C-262T C/T demonstrated the OR for CKD of 0.67 (95% CI 0.43–1.06) with the marginally significant trend for decreased odds ratio with increasing numbers of T allele (p = 0.070). There were no significant associations between the other polymorphisms with CKD risk. The present study found a marginally significant trend of the decreased risk of CKD with increasing numbers of T allele of CAT, which may suggest the possibility of personalized risk estimation of this life-limiting disease in the near future.

Gene-gene combination effect and interactions among ABCA1, APOA1, SR-B1, and CETP polymorphisms for serum high-density lipoprotein-cholesterol in the Japanese population.

Background/Objective Gene-gene interactions in the reverse cholesterol transport system for high-density lipoprotein-cholesterol (HDL-C) are poorly understood. The present study observed gene-gene combination effect and interactions between single nucleotide polymorphisms (SNPs) in ABCA1, APOA1, SR-B1, and CETP in serum HDL-C from a cross-sectional study in the Japanese population. Methods The study population comprised 1,535 men and 1,515 women aged 35–69 years who were enrolled in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study. We selected 13 SNPs in the ABCA1, APOA1, CETP, and SR-B1 genes in the reverse cholesterol transport system. The effects of genetic and environmental factors were assessed using general linear and logistic regression models after adjusting for age, sex, and region. Principal Findings Alcohol consumption and daily activity were positively associated with HDL-C levels, whereas smoking had a negative relationship. The T allele of CETP, rs3764261, was correlated with higher HDL-C levels and had the highest coefficient (2.93 mg/dL/allele) among the 13 SNPs, which was statistically significant after applying the Bonferroni correction (p<0.001). Gene-gene combination analysis revealed that CETP rs3764261 was associated with high HDL-C levels with any combination of SNPs from ABCA1, APOA1, and SR-B1, although no gene-gene interaction was apparent. An increasing trend for serum HDL-C was also observed with an increasing number of alleles (p<0.001). Conclusions The present study identified a multiplier effect from a polymorphism in CETP with ABCA1, APOA1, and SR-B1, as well as a dose-dependence according to the number of alleles present.