The frequency of major ABCG2, SLCO1B1 and CYP2C9 variants in Asian, Native Hawaiian and Pacific Islander women subgroups: implications for personalized statins dosing.

Aim: The frequencies of SLCO1B1*5 and CYP2C9*2 and *3 in specific Asian, Native Hawaiian and Pacific Islander (NHPI) subgroups are unknown. Patients & methods: Repository DNA samples from 1064 women self-identifying as Filipino, Korean, Japanese, Native Hawaiian, Marshallese or Samoan and aged 18 years or older were used for targeted sequencing of three genetic variants (rs4149056, rs1799853 and rs1057910). Results: SLCO1B1*5 was significantly less frequent in NHPI women (0.5-6%) than in Europeans (16%). Except for Koreans, CYP2C9*2 (0-1.4%) and *3 (0.5-3%) were significantly less frequent in all subgroups than in Europeans (8 and 12.7%, respectively). Prior reports showed that Asian and NHPI individuals have significantly higher ABCG2 Q141K allele frequency (13-46%) than Europeans (9.4%). Combined phenotype rates for rosuvastatin and fluvastatin revealed that Filipinos and Koreans had the highest frequencies of statin-associated myopathy symptoms risk alleles. Conclusion: Differences in ABCG2, SLCO1B1 and CYP2C9 allele frequencies among different racial and ethnic subgroups highlight the need for increased diversity in pharmacogenetic research. Risk alleles for statin-associated myopathy symptoms are more prevalent in Filipinos, underscoring the importance of genotype-based statin dosing.

Statins are medications used to lower low-density lipoprotein ('bad') cholesterol. Variation in genes for proteins which transport drugs (SLCO1B1 and ABCG2) or metabolize drugs (CYP2C9) may significantly influence how much statin someone is exposed to. Genetic variants within SLCO1B1 can affect exposure to all statins, while variants within ABCG2 and CYP2C9 can affect exposure to rosuvastatin and fluvastatin, respectively. The prevalence of the decreased or no-function genetic variants is unknown among Filipino and Native Hawaiian and Pacific Islander (NHPI) subgroups. The major racial categorization of 'Asians and NHPI' (ANHPI) can miss potential genetic and ancestral differences among population subgroups. Our study used biobank data from 1064 women of ANHPI descent to estimate the frequencies of four important variants within SLCO1B1, ABCG2 and CYP2C9. Those of ANHPI ancestry were less likely to have variations in SLCO1B1 and CYP2C9 but significantly more likely to have nonfunctional ABCG2 than Europeans. Our findings provide insight into SLCO1B1 and CYP2C9 genetic variations among under-represented subgroups. Specifically, Filipinos and Koreans have the highest rates of higher risk genetic variants linked to high rosuvastatin and fluvastatin exposure and muscle-related side effects. Estimating the frequency of genetic variations in under-represented subgroups is pivotal in reducing health disparities in treatment outcomes, diversifying pharmacogenetic research and advancing personalized medicine.

The frequency of rs2231142 in ABCG2 among Native Hawaiian and Pacific Islander subgroups: implications for personalized rosuvastatin dosing.

Statins are among the most commonly prescribed medications worldwide. Rosuvastatin is a moderate- to high-intensity statin depending on the prescribed dose. Statin-associated muscle symptoms are the main side effects, contributing to low adherence to statins. The missense variant rs2231142 in ABCG2 affects the functionality of the ABCG2 transporter, altering the pharmacokinetics and pharmacodynamics of rosuvastatin. This special report aims to accentuate the importance of considering the ABCG2 genotype upon prescribing rosuvastatin in high cardiovascular disease risk subgroups, specifically Native Hawaiian and Pacific Islander populations. Based on the reported frequencies of rs2231142 in ABCG2, it may be justifiable to initiate low-dose rosuvastatin in Samoans relative to Marshallese or Native Hawaiians. Interpopulation differences in pharmacogenetic allele frequencies underscore the need to disaggregate broad population categories to achieve health equity in treatment outcomes.

Rosuvastatin is a medication that is used to decrease levels of bad cholesterol in the blood. One of the side effects of rosuvastatin is muscle aches, which can cause patients to stop taking their medication. ABCG2 is a gene responsible for encoding ABCG2, an important transporter that plays a role in how the body interacts with many medications, including rosuvastatin. Genetic variations in ABCG2 result in a functional or nonfunctional transporter. This special report aims to focus on the importance of considering genetic variations in ABCG2 among different population subgroups, in particular Native Hawaiians, Samoans and Marshallese. The ABCG2 genotype could inform clinicians about the most effective rosuvastatin dose to prescribe. This approach highlights the importance of individualized patient characteristics above and beyond race and ethnicity.

Investigating disparity in access to Australian clinical genetic health services for Aboriginal and Torres Strait Islander people.

Globally, there is a recognised need that all populations should be able to access the benefits of genomics and precision medicine. However, achieving this remains constrained by a paucity of data that quantifies access to clinical genomics, particularly amongst Indigenous populations. Using administrative data from clinical genetic health services across three Australian jurisdictions (states/territories), we investigate disparities in the scheduling and attendance of appointments among Aboriginal and/or Torres Strait Islander people, compared to non-Indigenous people. For 14,870 appointments scheduled between 2014-2018, adjusted Multivariate Poisson Regression models revealed that Aboriginal and/or Torres Strait Islander people were scheduled fewer appointments (IRR 0.73 [0.68-0.80], <0.001) and attended at lower rates (IRR 0.85 [0.78-0.93], <0.001). Within this population, adults, females, remote residents, and those presenting in relation to cancer or prenatal indications experienced the greatest disparity in access. These results provide important baseline data related to disparities in access to clinical genomics in Australia.

A Polynesian-specific copy number variant encompassing the MICA gene associates with gout.

Gout is of particularly high prevalence in the Maori and Pacific (Polynesian) populations of Aotearoa New Zealand (NZ). Here, we investigated the contribution of common population-specific copy number variation (CNV) to gout in the Aotearoa NZ Polynesian population. Microarray-generated genome-wide genotype data from Aotearoa NZ Polynesian individuals with (n = 1196) and without (n = 1249) gout were analyzed. Comparator population groups were 552 individuals of European ancestry and 1962 of Han Chinese ancestry. Levels of circulating major histocompatibility complex (MHC) class I polypeptide-related sequence A (MICA) were measured by enzyme-linked immunosorbent assay. Fifty-four CNV regions (CNVRs) appearing in at least 10 individuals were detected, of which seven common (>2%) CNVRs were specific to or amplified in Polynesian people. A burden test of these seven revealed associations of insertion/deletion with gout (odds ratio (OR) 95% confidence interval [CI] = 1.80 [1.01; 3.22], P = 0.046). Individually testing of the seven CNVRs for association with gout revealed nominal association of CNVR1 with gout in Western Polynesian (Chr6: 31.36-31.45 Mb, OR = 1.72 [1.03; 2.92], P = 0.04), CNVR6 in the meta-analyzed Polynesian sample sets (Chr1: 196.75-196.92 Mb, OR = 1.86 [1.16; 3.00], P = 0.01) and CNVR9 in Western Polynesian (Chr1: 189.35-189.54 Mb, OR = 2.75 [1.15; 7.13], P = 0.03). Analysis of European gout genetic association data demonstrated a signal of association at the CNVR1 locus that was an expression quantitative trait locus for MICA. The most common CNVR (CNVR1) includes deletion of the MICA gene, encoding an immunomodulatory protein. Expression of MICA was reduced in the serum of individuals with the deletion. In summary, we provide evidence for the association of CNVR1 containing MICA with gout in Polynesian people, implicating class I MHC-mediated antigen presentation in gout.

Dementia Incidence, APOE Genotype, and Risk Factors for Cognitive Decline in Aboriginal Australians: A Longitudinal Cohort Study.

BACKGROUND AND OBJECTIVES: Aboriginal Australians are disproportionately affected by dementia, with incidence in remote populations approximately double that of non-Indigenous populations. This study aimed to identify dementia incidence and risk factors in Aboriginal Australians residing in urban areas, which are currently unknown. METHODS: A population-based cohort of Aboriginal Australians ≥60 years of age was assessed at baseline and 6-year follow-up. Life-course risk factors (baseline) were examined for incident dementia or mild cognitive impairment (MCI) through logistic regression analyses; adjustments were made for age. APOE genotyping was available for 86 people. RESULTS: Data were included from 155 participants 60 to 86 years of age (mean 65.70 years, SD 5.65 years; 59 male). There were 16 incident dementia cases (age-standardized rate 35.97/1,000 person-years, 95% confidence interval [CI] 18.34-53.60) and 36 combined incident MCI and dementia cases. Older age (odds ratio [OR] 2.29, 95% CI 1.42-3.70), male sex (OR 4.14, 95% CI 1.60-10.77), unskilled work history (OR 5.09, 95% CI 1.95-13.26), polypharmacy (OR 3.11, 95% CI 1.17-8.28), and past smoking (OR 0.24, 95% CI 0.08-0.75) were associated with incident MCI/dementia in the final model. APOE ε4 allele frequency was 24%; heterozygous or homozygous ε4 was associated with incident MCI/dementia (bivariate OR 3.96, 95% CI 1.25-12.50). DISCUSSION: These findings provide evidence for higher dementia incidence in Aboriginal Australians from urban areas, where the majority of Aboriginal people reside. This study also sheds light on sociodemographic, health, and genetic factors associated with incident MCI/dementia at older ages in this population, which is critical for targeted prevention strategies.

Ethnic differences in excretion of butadiene-DNA adducts by current smokers.

1,3-Butadiene (BD) is a known human carcinogen used in the synthetic polymer industry and also found in cigarette smoke, automobile exhaust and wood burning smoke. BD is metabolically activated by cytochrome P450 monooxygenases (CYP) 2E1 and 2A6 to 3,4-epoxy-1-butene (EB), which can be detoxified by GST-catalyzed glutathione conjugation or hydrolysis. We have previously observed ethnic differences in urinary levels of EB-mercapturic acids in white, Japanese American and Native Hawaiian smokers. In the present study, similar analyses were extended to urinary BD-DNA adducts. BD-induced N7-(1-hydroxy-3-buten-2-yl) guanine (EB-GII) adducts were quantified in urine samples obtained from smokers and non-smokers belonging to three racial/ethnic groups: white, Japanese American and Native Hawaiian. After adjusting for sex, age, nicotine equivalents, body mass index and batch, we found that Japanese American smokers excreted significantly higher amounts of urinary EB-GII than whites [1.45 (95% confidence interval: 1.12-1.87) versus 0.68 (95% confidence interval: 0.52-0.85) fmol/ml urine, P = 4 × 10-5]. Levels of urinary EB-GII in Native Hawaiian smokers were not different from those in whites [0.67 (95% confidence interval: 0.51-0.84) fmol/ml urine, P = 0.938]. There were no racial/ethnic differences in urinary EB-GII adduct levels in non-smokers. Racial/ethnic differences in urinary EB-GII adduct levels in smokers could not be explained by GSTT1 gene deletion or CYP2A6 enzymatic activity. Urinary EB-GII adduct levels in smokers were significantly associated with concentrations of BD metabolite dihyroxybutyl mercapturic acid. Overall, our results reveal that urinary EB-GII adducts in smokers differ across racial/ethnic groups. Future studies are required to understand genetic and epigenetic factors that may be responsible for these differences.

Childhood prevalence of achondroplasia in New South Wales and the Australian Capital Territory, Australia.

The aim of this study was to estimate the childhood prevalence of achondroplasia, trends over time in birth prevalence, and age at diagnosis in Australia. Children born between 1990 and 2019 with a clinical and radiological and/or molecular diagnosis of achondroplasia were identified from a tertiary hospital servicing New South Wales (NSW) and the Australian Capital Territory (ACT) and compared with population data from the Australian Bureau of Statistics. Childhood prevalence of achondroplasia, based on children ≤19 years of age and resident in NSW/ACT on June 30, 2019 (n = 109), was 5.2 per 100,000. A total of 127 individuals with achondroplasia were born in 1990-2019 in NSW/ACT. Birth prevalence rates increased across birth decades, from 3.3 per 100,000 live births in 1990-1999 to 5.3 per 100,000 in 2010-2019 (p < 0.0001). Median age at diagnosis decreased to 17 days in 2010-2019 compared with 30 days in 1990-1999 (p = 0.035), although the overall decreasing trend across consecutive decades did not reach statistical significance. This is the first study to show a rising birth prevalence rate for achondroplasia in Australia with a concurrent decreasing age at diagnosis, both of which were statistically significant after 2 decades.

Multiethnic genome-wide association study of differentiated thyroid cancer in the EPITHYR consortium.

Incidence of differentiated thyroid carcinoma (DTC) varies considerably between ethnic groups, with particularly high incidence rates in Pacific Islanders. DTC is one of the cancers with the highest familial risk suggesting a major role of genetic risk factors, but only few susceptibility loci were identified so far. In order to assess the contribution of known DTC susceptibility loci and to identify new ones, we conducted a multiethnic genome-wide association study (GWAS) in individuals of European ancestry and of Oceanian ancestry from Pacific Islands. Our study included 1554 cases/1973 controls of European ancestry and 301 cases/348 controls of Oceanian ancestry from seven population-based case-control studies participating to the EPITHYR consortium. All participants were genotyped using the OncoArray-500K Beadchip (Illumina). We confirmed the association with the known DTC susceptibility loci at 2q35, 8p12, 9q22.33 and 14q13.3 in the European ancestry population and suggested two novel signals at 1p31.3 and 16q23.2, which were associated with thyroid-stimulating hormone levels in previous GWAS. We additionally replicated an association with 5p15.33 reported previously in Chinese and European populations. Except at 1p31.3, all associations were in the same direction in the population of Oceanian ancestry. We also observed that the frequencies of risk alleles at 2q35, 5p15.33 and 16q23.2 were significantly higher in Oceanians than in Europeans. However, additional GWAS and epidemiological studies in Oceanian populations are needed to fully understand the highest incidence observed in these populations.

The impact of global and local Polynesian genetic ancestry on complex traits in Native Hawaiians.

Epidemiological studies of obesity, Type-2 diabetes (T2D), cardiovascular diseases and several common cancers have revealed an increased risk in Native Hawaiians compared to European- or Asian-Americans living in the Hawaiian islands. However, there remains a gap in our understanding of the genetic factors that affect the health of Native Hawaiians. To fill this gap, we studied the genetic risk factors at both the chromosomal and sub-chromosomal scales using genome-wide SNP array data on ~4,000 Native Hawaiians from the Multiethnic Cohort. We estimated the genomic proportion of Native Hawaiian ancestry ("global ancestry," which we presumed to be Polynesian in origin), as well as this ancestral component along each chromosome ("local ancestry") and tested their respective association with binary and quantitative cardiometabolic traits. After attempting to adjust for non-genetic covariates evaluated through questionnaires, we found that per 10% increase in global Polynesian genetic ancestry, there is a respective 8.6%, and 11.0% increase in the odds of being diabetic (P = 1.65×10-4) and having heart failure (P = 2.18×10-4), as well as a 0.059 s.d. increase in BMI (P = 1.04×10-10). When testing the association of local Polynesian ancestry with risk of disease or biomarkers, we identified a chr6 region associated with T2D. This association was driven by an uniquely prevalent variant in Polynesian ancestry individuals. However, we could not replicate this finding in an independent Polynesian cohort from Samoa due to the small sample size of the replication cohort. In conclusion, we showed that Polynesian ancestry, which likely capture both genetic and lifestyle risk factors, is associated with an increased risk of obesity, Type-2 diabetes, and heart failure, and that larger cohorts of Polynesian ancestry individuals will be needed to replicate the putative association on chr6 with T2D.

Molecular characterisation of osteoblasts from bone obtained from people of Polynesian and European ancestry undergoing joint replacement surgery.

Population studies in Aotearoa New Zealand found higher bone mineral density and lower rate of hip fracture in people of Polynesian ancestry compared to Europeans. We hypothesised that differences in osteoblast proliferation and differentiation contribute to the differences in bone properties between the two groups. Osteoblasts were cultured from bone samples obtained from 30 people of Polynesian ancestry and 25 Europeans who had joint replacement surgeries for osteoarthritis. The fraction of cells in S-phase was determined by flow cytometry, and gene expression was analysed by microarray and real-time PCR. We found no differences in the fraction of osteoblasts in S-phase between the groups. Global gene expression analysis identified 79 differentially expressed genes (fold change > 2, FDR P < 0.1). Analysis of selected genes by real-time PCR found higher expression of COL1A1 and KRT34 in Polynesians, whereas BGLAP, DKK1, NOV, CDH13, EFHD1 and EFNB2 were higher in Europeans (P ≤ 0.01). Osteoblasts from European donors had higher levels of late differentiation markers and genes encoding proteins that inhibit the Wnt signalling pathway. This variability may contribute to the differences in bone properties between people of Polynesian and European ancestry that had been determined in previous studies.

A missense variant in CREBRF, rs373863828, is associated with fat-free mass, not fat mass in Samoan infants.

BACKGROUND/OBJECTIVES: In Samoa, where 80% of the adult population is living with obesity, understanding the determinants of adiposity and growth during infancy may inform prevention efforts. We examined the association of a missense variant, rs373863828, in the CREBRF gene with body composition in Samoan infants. Adults with one or more copies of the rs373863828 minor allele (A) have higher odds of obesity, based on body-mass index (BMI), but paradoxically decreased odds of diabetes compared to those without the allele. Our study may offer novel insight into the natural history and pathogenesis of this unexpected relationship. SUBJECTS/METHODS: In a prospective study, we measured body composition in early infancy, and at 2- and 4-months of age using anthropometry and dual-energy x-ray absorptiometry (DXA). We genotyped subjects at the CREBRF rs373863828 locus and compared infants with (AA/AG) and without (GG) the variant. In longitudinal analyses, we calculated the absolute change in each outcome from the early infant to the 4-month assessment, adjusting for baseline and other covariates. RESULTS: In cross-sectional analyses, there was no significant difference in infant BMI or fat mass by genotype. After adjusting for covariates, infants with the variant had 4.0 ± 1.8 g more bone mass (p = 0.026) and 210.9 ± 79.6 g more lean mass (p = 0.009) at 4-months and accumulated 176.9 ± 73.0 g more lean mass between the early infant and 4-month assessment (p = 0.017). CONCLUSIONS: The CREBRF rs373863828 minor allele (A) was not associated with increased BMI or adiposity in Samoan infants, but instead with increased lean and bone mass. Our findings suggest that lean (i.e., muscle) and bone mass accretion should be explored as pathways to explain the "protective" effect of the CREBRF variant against diabetes.

The Pacific-specific CREBRF rs373863828 allele protects against gestational diabetes mellitus in Maori and Pacific women with obesity.

AIMS/HYPOTHESIS: The CREBRF rs373863828 minor (A) allele is associated with increased BMI but reduced prevalence of type 2 diabetes in Maori and Pacific people. Given the shared aetiology of type 2 diabetes and gestational diabetes mellitus (GDM), we tested for an association between the CREBRF rs373863828 variant and GDM. METHODS: We conducted a prospective cohort study of Maori and Pacific women nested within a nutritional intervention study for pregnant women with obesity. Women were enrolled at 12-17 weeks' gestation and underwent anthropometry and collection of buffy coats for later genetic testing. GDM was diagnosed by 75 g OGTT at 24-28 weeks' gestation using the International Association of Diabetes and Pregnancy Study Groups criteria. Genotyping was performed by real-time PCR with a custom CREBRF rs373863828 probe-set. The association between CREBRF rs373863828 and GDM was analysed separately by ethnic group using logistic regression, with effect estimates combined in a meta-analysis. RESULTS: Of 112 Maori and Pacific pregnant women with obesity, 31 (28%) carried the CREBRF rs373863828 A allele (A/G or A/A) and 35 (31%) developed GDM. Women who carried the CREBRF rs373863828 A allele did not differ in BMI when compared with non-carriers (G/G). There was a fivefold reduction in the likelihood of GDM per CREBRF rs373863828 A allele (OR 0.19 [95% CI 0.05, 0.69], p = 0.01), independent of age, BMI and family history of diabetes (adjusted OR 0.13 [95% CI 0.03, 0.53], p = 0.004). GDM was diagnosed in 10% and 40% of women with and without the CREBRF rs373863828 A allele, respectively (no woman with the A/A genotype developed GDM). CONCLUSIONS/INTERPRETATION: The CREBRF rs373863828 (A) allele is associated with reduced likelihood of GDM in Maori and Pacific women with obesity and may improve GDM risk prediction. Graphical abstract.

Population-specific reference panels are crucial for genetic analyses: an example of the CREBRF locus in Native Hawaiians.

Statistical imputation applied to genome-wide array data is the most cost-effective approach to complete the catalog of genetic variation in a study population. However, imputed genotypes in underrepresented populations incur greater inaccuracies due to ascertainment bias and a lack of representation among reference individuals, further contributing to the obstacles to study these populations. Here we examined the consequences due to the lack of representation by genotyping in a large number of self-reported Native Hawaiians (N = 3693) a functionally important, Polynesian-specific variant in the CREBRF gene, rs373863828. We found the derived allele was significantly associated with several adiposity traits with large effects (e.g. ~ 1.28 kg/m2 per allele in body mass index as the most significant; P = 7.5 × 10-5), consistent with the original findings in Samoans. Due to the current absence of Polynesian representation in publicly accessible reference sequences, rs373863828 or its proxies could not be tested through imputation using these existing resources. Moreover, the association signals at the entire CREBRF locus could not be captured by alternative approaches, such as admixture mapping. In contrast, highly accurate imputation can be achieved even if a small number (<200) of internally constructed Polynesian reference individuals were available; this would increase sample size and improve the statistical evidence of associations. Taken together, our results suggest the alarming possibility that lack of representation in reference panels could inhibit discovery of functionally important loci such as CREBRF. Yet, they could be easily detected and prioritized with improved representation of diverse populations in sequencing studies.

ADH1B∗2 Is Associated With Reduced Severity of Nonalcoholic Fatty Liver Disease in Adults, Independent of Alcohol Consumption.

BACKGROUND & AIMS: Alcohol dehydrogenase 1B (ADH1B) is involved in alcohol metabolism. The allele A (ADH1B∗2) of the rs1229984: A>G variant in ADH1B is associated with a higher alcohol metabolizing activity compared to the ancestral allele G (ADH1B∗1). Moderate alcohol consumption is associated with reduced severity of nonalcoholic fatty liver disease (NAFLD), based on histologic analysis, compared with no alcohol consumption. However, it is unclear whether ADH1B∗2 modifies the relationship between moderate alcohol consumption and severity of NAFLD. We examined the association between ADH1B∗2 and moderate alcohol consumption and histologic severity of NAFLD. METHODS: We collected data from 1557 multiethnic adult patients with biopsy-proven NAFLD enrolled into 4 different studies conducted by the Nonalcoholic Steatohepatitis (NASH) Clinical Research Network. Histories of alcohol consumption were obtained from answers to standardized questionnaires. Liver biopsy samples were analyzed by histology and scored centrally according to the NASH Clinical Research Network criteria. We performed covariate adjusted logistic regressions to identify associations between histologic features of NAFLD severity and moderate alcohol consumption and/or ADH1B∗2. RESULTS: A higher proportion of Asians/Pacific Islanders/Hawaiians carried the ADH1B∗2 allele (86%) than other racial groups (4%-13%). However, the study population comprised mostly non-Hispanic whites (1153 patients, 74%), so the primary analysis focused on this group. Among them, 433 were moderate drinkers and 90 were ADH1B∗2 carriers. After we adjusted for confounders, including alcohol consumption status, ADH1B∗2 was associated with lower frequency of steatohepatitis (odds ratio [OR], 0.52; P < .01) or fibrosis (odds ratio, 0.69; P = .050) compared with ADH1B∗1. Moderate alcohol consumption (g/d) reduced the severity of NAFLD in patients with ADH1B∗1 or ADH1B∗2. However, ADH1B∗2, compared to ADH1B∗1, was associated with a reduced risk of definite NASH (ADH1B∗2: OR, 0.80; P < .01 vs ADH1B∗1: OR, 0.96; P = .036) and a reduced risk of an NAFLD activity score of 4 or higher (ADH1B∗2: OR, 0.83; P = .012 vs ADH1B∗1: OR, 0.96; P = .048) (P < .01 for the difference in the effect of moderate alcohol consumption between alleles). The relationship between body mass index and NAFLD severity was significantly modified by ADH1B∗2, even after we controlled for alcohol consumption. CONCLUSIONS: ADH1B∗2 reduces the risk of NASH and fibrosis in adults with NAFLD regardless of alcohol consumption status. ADH1B∗2 might modify the association between high body mass index and NAFLD severity.

Pleiotropic effect of the ABCG2 gene in gout: involvement in serum urate levels and progression from hyperuricemia to gout.

BACKGROUND: The ABCG2 Q141K (rs2231142) and rs10011796 variants associate with hyperuricaemia (HU). The effect size of ABCG2 rs2231142 on urate is ~ 60% that of SLC2A9, yet the effect size on gout is greater. We tested the hypothesis that ABCG2 plays a role in the progression from HU to gout by testing for association of ABCG2 rs2231142 and rs10011796 with gout using HU controls. METHODS: We analysed 1699 European gout cases and 14,350 normouricemic (NU) and HU controls, and 912 New Zealand (NZ) Polynesian (divided into Eastern and Western Polynesian) gout cases and 696 controls. Association testing was performed using logistic and linear regression with multivariate adjusting for confounding variables. RESULTS: In Europeans and Polynesians, the ABCG2 141K (T) allele was associated with gout using HU controls (OR = 1.85, P = 3.8E- 21 and ORmeta = 1.85, P = 1.3E- 03, respectively). There was evidence for an effect of 141K in determining HU in European (OR = 1.56, P = 1.7E- 18) but not in Polynesian (ORmeta = 1.49, P = 0.057). For SLC2A9 rs11942223, the T allele associated with gout in the presence of HU in European (OR = 1.37, P = 4.7E- 06), however significantly weaker than ABCG2 rs2231142 141K (PHet = 0.0023). In Western Polynesian and European, there was epistatic interaction between ABCG2 rs2231142 and rs10011796. Combining the presence of the 141K allele with the rs10011796 CC-genotype increased gout risk, in the presence of HU, 21.5-fold in Western Polynesian (P = 0.009) and 2.6-fold in European (P = 9.9E- 06). The 141K allele of ABCG2 associated with increased gout flare frequency in Polynesian (Pmeta = 2.5E- 03). CONCLUSION: These data are consistent with a role for ABCG2 141K in gout in the presence of established HU.

Rare genetic variants in interleukin-37 link this anti-inflammatory cytokine to the pathogenesis and treatment of gout.

OBJECTIVE: Gout is characterised by severe interleukin (IL)-1-mediated joint inflammation induced by monosodium urate crystals. Since IL-37 is a pivotal anti-inflammatory cytokine suppressing the activity of IL-1, we conducted genetic and functional studies aimed at elucidating the role of IL-37 in the pathogenesis and treatment of gout. METHODS: Variant identification was performed by DNA sequencing of all coding bases of IL37 using molecular inversion probe-based resequencing (discovery cohort: gout n=675, controls n=520) and TaqMan genotyping (validation cohort: gout n=2202, controls n=2295). Predictive modelling of the effects of rare variants on protein structure was followed by in vitro experiments evaluating the impact on protein function. Treatment with recombinant IL-37 was evaluated in vitro and in vivo in a mouse model of gout. RESULTS: We identified four rare variants in IL37 in six of the discovery gout patients; p.(A144P), p.(G174Dfs*16), p.(C181*) and p.(N182S), whereas none emerged in healthy controls (Fisher's exact p-value=0.043). All variants clustered in the functional domain of IL-37 in exon 5 (p-value=5.71×10-5). Predictive modelling and functional studies confirmed loss of anti-inflammatory functions and we substantiated the therapeutic potential of recombinant IL-37 in the treatment of gouty inflammation. Furthermore, the carrier status of p.(N182S)(rs752113534) was associated with increased risk (OR=1.81, p-value=0.031) of developing gout in hyperuricaemic individuals of Polynesian ancestry. CONCLUSION: Here, we provide genetic as well as mechanistic evidence for the role of IL-37 in the pathogenesis of gout, and highlight the therapeutic potential of recombinant IL-37 for the treatment of gouty arthritis.

The Maori and Pacific specific CREBRF variant and adult height.

BACKGROUND: The CREBRF missense variant (p.Arg457Gln) is paradoxically associated with lower risk of type 2 diabetes, yet higher body mass index (BMI). Here we sought to determine whether this CREBRF variant might be associated with adult height. METHODS: Linear regression was used to analyse the association of the CREBRF minor (A) allele with height in 2286 Maori and Pacific adults living in Aotearoa/New Zealand. A potential type 2 diabetes index event was corrected to account for a bias that may be the cause of paradoxical association between the CREBRF diabetes-protective allele and higher BMI and height. RESULTS: The CREBRF protective allele was associated with increased adult height (ß = 1.25 cm, P = 3.9 × 10-6), with the effect being more pronounced in males. The lower odds of diabetes remained similar when analyses were adjusted for height (OR = 0.67-0.65). We found no evidence of a diabetes index event bias to explain the paradoxical effect of CREBRF with either BMI or height and diabetes. The orthologous CREBRF p.Arg457Gln variant was created in knock-in mice to independently assess the effect of the variant, and length was found to be greater in male mice at 8 weeks of age. CONCLUSION: These data taken together indicate that CREBRF p.Arg457Gln is associated with taller stature in Maori and Pacific adults.

Association of internal smoking dose with blood DNA methylation in three racial/ethnic populations.

BACKGROUND: Lung cancer is the leading cause of cancer-related death. While cigarette smoking is the primary cause of this malignancy, risk differs across racial/ethnic groups. For the same number of cigarettes smoked, Native Hawaiians compared to whites are at greater risk and Japanese Americans are at lower risk of developing lung cancer. DNA methylation of specific CpG sites (e.g., in AHRR and F2RL3) is the most common blood epigenetic modification associated with smoking status. However, the influence of internal smoking dose, measured by urinary nicotine equivalents (NE), on DNA methylation in current smokers has not been investigated, nor has a study evaluated whether for the same smoking dose, circulating leukocyte DNA methylation patterns differ by race. METHODS: We conducted an epigenome-wide association study (EWAS) of NE in 612 smokers from three racial/ethnic groups: whites (n = 204), Native Hawaiians (n = 205), and Japanese Americans (n = 203). Genome-wide DNA methylation profiling of blood leukocyte DNA was measured using the Illumina 450K BeadChip array. Average ß value, the ratio of signal from a methylated probe relative to the sum of the methylated and unmethylated probes at that CpG, was the dependent variables in linear regression models adjusting for age, sex, race (for pan-ethnic analysis), and estimated cell-type distribution. RESULTS: We found that NE was significantly associated with six differentially methylated CpG sites (Bonferroni corrected p < 1.48 × 10-7): four in or near the FOXK2, PBX1, FNDC7, and FUBP3 genes and two in non-annotated genetic regions. Higher levels of NE were associated with increasing methylation beta-valuesin all six sites. For all six CpG sites, the association was only observed in Native Hawaiians, suggesting that the influence of smoking dose on DNA methylation patterns is heterogeneous across race/ethnicity (p interactions < 8.8 × 10-8). We found two additional CpG sites associated with NE in only Native Hawaiians. CONCLUSIONS: In conclusion, internal smoking dose was associated with increased DNA methylation in circulating leukocytes at specific sites in Native Hawaiian smokers but not in white or Japanese American smokers.

Discordant association of the CREBRF rs373863828 A allele with increased BMI and protection from type 2 diabetes in Maori and Pacific (Polynesian) people living in Aotearoa/New Zealand.

AIMS/HYPOTHESIS: The A (minor) allele of CREBRF rs373863828 has been associated with increased BMI and reduced risk of type 2 diabetes in the Samoan populations of Samoa and American Samoa. Our aim was to test rs373863828 for associations with BMI and the odds of type 2 diabetes, gout and chronic kidney disease (CKD) in Maori and Pacific (Polynesian) people living in Aotearoa/New Zealand. METHODS: Linear and logistic regression models were used to analyse the association of the A allele of CREBRF rs373863828 with BMI, log-transformed BMI, waist circumference, type 2 diabetes, gout and CKD in 2286 adults. The primary analyses were adjusted for age, sex, the first four genome-wide principal components and (where appropriate) BMI, waist circumference and type 2 diabetes. The primary analysis was conducted in ancestrally defined groups and association effects were combined using meta-analysis. RESULTS: For the A allele of rs373863828, the effect size was 0.038 (95% CI 0.022, 0.055, p = 4.8 × 10-6) for log-transformed BMI, with OR 0.59 (95% CI 0.47, 0.73, p = 1.9 × 10-6) for type 2 diabetes. There was no evidence for an association of genotype with variance in BMI (p = 0.13), and nor was there evidence for associations with serum urate (ß = 0.012 mmol/l, pcorrected = 0.10), gout (OR 1.00, p = 0.98) or CKD (OR 0.91, p = 0.59). CONCLUSIONS/INTERPRETATION: Our results in New Zealand Polynesian adults replicate, with very similar effect sizes, the association of the A allele of rs373863828 with higher BMI but lower odds of type 2 diabetes among Samoan adults living in Samoa and American Samoa.

Widespread prevalence of a CREBRF variant amongst Maori and Pacific children is associated with weight and height in early childhood.

OBJECTIVE: Investigating a large and ethnically diverse cohort from the Pacific region, we aimed to replicate and extend the recently reported findings that a CREBRF genetic variant is strongly associated with body mass index in Samoans. METHODS: A birth cohort of more than six thousand children was utilised. In this study, genotyping of two markers (rs12513649 and rs373863828) was undertaken in Maori, Pacific, European and Asian individuals in the cohort. RESULTS: We report that these CREBRF genetic variants are not confined to Samoans but are prevalent in all other Pacific populations sampled, including Maori. We found that the rs373863828 variant was significantly associated with growth at 4 years of age. On average, we observed allele-specific increases in weight (P=0·004, +455 g, s.e. 0.158), height (P=0·007, +0·70 cm, s.e. 0.26) and waist circumference (P=0·004, +0·70 cm, s.e. 0.24) at 4 years of age. The rs373863828 variant was not associated with birth weight (P=0·129). CONCLUSIONS: We replicated the finding that a CREBRF variant is associated with increased body mass. We then built on the original findings by demonstrating the prevalence of the rs12513649 and rs373863828 variants in multiple Pacific population groups and by demonstrating that the rs373863828 variant is associated with growth in early childhood. Pacific population groups experience a disproportionately high burden of obesity, starting in early childhood. This new knowledge offers potential for evidence-based interventions aimed at establishing healthy growth trajectories from the earliest possible age.