The interaction of rs738409, obesity, and alcohol: a population-based autopsy study.
ABSTRACT: OBJECTIVES:The objective of this study was to access the prevalence of alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) histology in the general population, which had been otherwise difficult to access because of inherent misclassification bias in surrogate marker studies and referral bias in patient case series. The interaction among rs738409, obesity, and alcohol remains controversial. This population-based autopsy study investigated the histological prevalence of ALD and NAFLD, and interactions among rs738409, obesity, and alcoholism. METHODS:A total of 170 alcoholic and 235 nonalcoholic cases were selected from 1,034 adult car accident autopsies in 17 Kansas and Missouri counties from 2000 to 2010. The nonalcoholic group had undetectable blood alcohol concentration, while the alcoholic group had a blood alcohol concentration ?0.08%. RESULTS:The age-standardized prevalences of hepatic steatosis, steatohepatitis, and advanced fibrosis were 56, 6, and 18% among alcoholics and 36, 4, and 6% in nonalcoholics, respectively. The interaction terms among alcohol, body mass index (BMI), and genotype were not significant. rs738409 GC or GG genotype was associated with 1.9-fold odds (95% confidence interval (CI), 1.2-2.9) of a higher NAFLD Activity Score (NAS). Alcohol had 3.5-fold odds (95% CI, 2.0-5.9), while every 5-unit increase in BMI had 1.9-fold odds (95% CI, 1.7-2.5). A negative interaction between alcohol and BMI towards fibrosis had been observed (P=0.045). Every 5-unit increase in BMI had 2.2-fold odds (95% CI, 1.5-2.5) of fibrosis among nonalcoholics, but not in alcoholics. CONCLUSIONS:This study assessed the prevalence of fatty liver histology in the general population from an autopsy study perspective. The finding of an additive interaction among rs738409, obesity, and alcohol towards NAS may be useful in targeting preventative care to patients at highest risk for ALD. The negative interaction between alcohol and obesity towards fibrosis supported previous findings and suggests the need for future research to explore potential mechanisms that may improve treatment of nonalcoholic steatohepatitis-related fibrosis.
Project description:Patatin-like phospholipase domain-containing protein 3 (PNPLA3) is a lipid droplet-associated protein that has been shown to have hydrolase activity toward triglycerides and retinyl esters. The first evidence of PNPLA3 being associated with fatty liver disease was revealed by a genome-wide association study (GWAS) of Hispanic, African American, and European American individuals in the Dallas Heart Study back in 2008. Since then, numerous GWAS reports have shown that PNPLA3 rs738409[G] (148M) variant is associated with hepatic triglyceride accumulation (steatosis), inflammation, fibrosis, cirrhosis, and even hepatocellular carcinoma regardless of etiologies including alcohol- or obesity-related and others. The frequency of PNPLA3(148M) variant ranges from 17% in African Americans, 23% in European Americans, to 49% in Hispanics in the Dallas Heart Study. Due to high prevalence of obesity and alcohol consumption in modern societies, the PNPLA3(148M) gene variant and environment interaction poses a serious concern for public health, especially chronic liver diseases including alcohol-related liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD). Therefore, PNPLA3(148M) variant is a potential therapeutic target for chronic liver disease in the rs738409 allele carriers. Currently, there is no approved drug specifically targeting the PNPLA3(148M) variant yet. With additional mechanistic studies, novel therapeutic strategies are expected to be developed for the treatment of the PNPLA3(148M) variant-associated chronic liver diseases in the near future.
Project description:BACKGROUND: In a genome-wide association scan, the single-nucleotide polymorphism (SNP) rs738409 in the patatin-like phospholipase 3 gene (PNPLA3) was strongly associated with increased liver fat content. We investigated whether this SNP is associated with the occurrence and progression of nonalcoholic fatty liver disease (NAFLD) in the Japanese population. METHODS: SNP rs738409 was genotyped by the Taqman assay in 253 patients with NAFLD (189 with nonalcoholic steatohepatitis [NASH] and 64 with simple steatosis) and 578 control subjects. All patients with NAFLD underwent liver biopsy. Control subjects had no metabolic disorders. For a case-control study, the χ(2)-test (additive model) was performed. Odds ratios (ORs) were adjusted for age, gender, and body mass index (BMI) by using multiple logistic regression analysis with genotypes (additive model), age, gender, and BMI as the independent variables. Multiple linear regression analysis was performed to test the independent effect of risk allele on clinical parameters while considering the effects of other variables (age, gender, and BMI), which were assumed to be independent of the effect of the SNP. RESULTS: The risk allele (G-allele) frequency of rs738409 was 0.44 in the control subjects and 0.60 in patients with NAFLD; this shows a strong association with NAFLD (additive model, P = 9.4 x 10(-10)). The OR (95% confidence interval) adjusted for age, gender, and BMI was 1.73 (1.25-2.38). Multiple linear regression analysis indicated that the G-allele of rs738409 was significantly associated with increases in aspartate transaminase (AST) (P = 0.00013), alanine transaminase (ALT) (P = 9.1 x 10(-6)), and ferritin levels (P = 0.014), and the fibrosis stage (P = 0.011) in the patients with NAFLD, even after adjustment for age, gender, and BMI. The steatosis grade was not associated with rs738409. CONCLUSIONS: We found that in the Japanese population, individuals harboring the G-allele of rs738409 were susceptible to NAFLD, and that rs738409 was associated with plasma levels of ALT, AST, and ferritin, and the histological fibrosis stage. Our study suggests that PNPLA3 may be involved in the progression of fibrosis in NAFLD.
Project description:Alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) are serious health problems worldwide. These two diseases have similar pathological spectra, ranging from simple hepatic steatosis to steatohepatitis, liver cirrhosis, and hepatocellular carcinoma. Although most subjects with excessive alcohol or food intake experience simple hepatic steatosis, a small percentage of individuals will develop progressive liver disease. Notably, both ALD and NAFLD are frequently accompanied by extrahepatic complications, including cardiovascular disease and malignancy. The survival of patients with ALD and NAFLD depends on various disease-associated conditions. This review delineates the clinical characteristics and outcomes of patients with ALD and NAFLD by comparing their epidemiology, the factors associated with disease susceptibility and progression, and the predictors and characteristics of outcomes. A comprehensive understanding of the characteristics and outcomes of ALD and NAFLD is imperative in the management of these chronic liver diseases.
Project description:Nonalcoholic fatty liver disease (NAFLD) is closely associated with obesity. Disulfide bond-forming oxidoreductase A-like protein (DsbA-L) is known to be a key molecule in protection against obesity and obesity-induced inflammation. In the present study, we used a modeling and simulation approach in an attempt to develop body mass index (BMI) and BMI-based NAFLD prediction models incorporating the DsbA-L polymorphism to predict the BMI and NAFLD in 341 elderly subjects. A nonlinear mixed-effect model best represented the sigmoidal relationship between the BMI and the logit function of the probability of NAFLD prevalence. The final models for BMI and NAFLD showed that DsbA-L rs1917760 polymorphism, age, and gender were associated with the BMI, whereas gender, patatin-like phospholipase 3 rs738409 polymorphism, HbA1c, and high-density and low-density lipoprotein cholesterol levels were associated with the risk of NAFLD. This information may aid in the genetic-based prevention of obesity and NAFLD in the general elderly population.
Project description:Aims:Prior studies have established variation at the PNPLA3 gene to be associated with a risk of developing alcoholic liver disease (ALD). We attempt to replicate this finding and other potential genetic variations previously associated with ALD utilizing a case-control design in a cohort of subjects with alcohol use disorders. Short summary:This case-control study performed in a US clinical sample of heavy drinkers, replicates the previously reported association between ALD and rs738409 polymorphism in the PNPLA3 gene in heavy drinkers. This association persisted after accounting for the subject's diabetes status. Methods:Patients of European ancestry with a history of ALD were identified (n = 169). Controls consisted of patients without ALD who were from the same cohorts and were ≥ 30 years of age, had lifetime total years drinking ≥20 and lifetime maximum drinks per day ≥12 (n = 259). Patients were genotyped for 40 candidate single nucleotide polymorphisms (SNPs) selected for the purpose of testing their association with ALD. The association of each SNP with ALD was tested using a logistic regression model, assuming log-additive allele effects. Bonferroni correction was applied and multivariable logistic regression models were used to account for relevant covariates. Results:Age, sex, and body mass index (BMI) distributions were similar between cases and controls. Diabetes was more prevalent in the ALD cases. Three SNPs were associated with ALD at the nominal significance level (rs738409 in PNPLA3, P = 0.00029; rs3741559 in AQP2, P = 0.0185; rs4290029 in NVL, P = 0.0192); only PNPLA3 rs738409 SNP was significant at the Bonferroni-corrected P-value threshold of 0.00125. Association results remained significant after adjustment for diabetes status. Conclusion:Our case-control study confirmed that PNPLA3 rs738409 SNP is associated with ALD. This is an important replication in a US clinical sample with control subjects who had long histories of alcohol consumption.
Project description:UNLABELLED:Genome-wide association studies identified single-nucleotide polymorphisms (SNPs) that are associated with increased hepatic fat or elevated liver enzymes, presumably reflecting nonalcoholic fatty liver disease (NAFLD). To investigate whether these SNPs are associated with histological severity of NAFLD, 1117 (894 adults/223 children) individuals enrolled in the Nonalcoholic Steatohepatitis (NASH) Clinical Research Network and National Institutes of Health Clinical Center studies with histologically confirmed NAFLD were genotyped for six SNPs that are associated with hepatic fat or liver enzymes in genome-wide association studies. In adults, three SNPs on chromosome 22 showed associations with histological parameters of NASH. After adjustment for age, sex, diabetes, and alcohol consumption, the minor allele of rs738409 C/G, a nonsynonymous coding SNP in the patatin-like phospholipase domain-containing protein 3 (PNPLA3) (adiponutrin) gene encoding an Ile148Met change, was associated with steatosis (P = 0.03), portal inflammation (P = 2.5 x 10(-4)), lobular inflammation (P = 0.005), Mallory-Denk bodies (P = 0.015), NAFLD activity score (NAS, P = 0.004), and fibrosis (P = 7.7 x 10(-6)). Two other SNPs in the same region demonstrated similar associations. Three SNPs on chromosome 10 near the CHUK (conserved helix-loop-helix ubiquitous kinase) gene were independently associated with fibrosis (P = 0.010). In children, no SNP was associated with histological severity. However, the rs738409 G allele was associated with younger age at the time of biopsy in multivariate analysis (P = 0.045). CONCLUSION:In this large cohort of histologically proven NAFLD, we confirm the association of the rs738409 G allele with steatosis and describe its association with histological severity. In pediatric patients, the high-risk rs738409 G allele is associated with an earlier presentation of disease. We also describe a hitherto unknown association between SNPs at a chromosome 10 locus and the severity of NASH fibrosis.
Project description:Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, with a prevalence of 25-30%. Since its first description in 1980, NAFLD has been conceived as a different entity from alcohol-related fatty liver disease (ALD), despite that, both diseases have an overlap in the pathophysiology, share genetic-epigenetic factors, and frequently coexist. Both entities are characterized by a broad spectrum of histological features ranging from isolated steatosis to steatohepatitis and cirrhosis. Distinction between NAFLD and ALD is based on the amount of consumed alcohol, which has been arbitrarily established. In this context, a proposal of positive criteria for NAFLD diagnosis not considering exclusion of alcohol consumption as a prerequisite criterion for diagnosis had emerged, recognizing the possibility of a dual etiology of fatty liver in some individuals. The impact of moderate alcohol use on the severity of NAFLD is ill-defined. Some studies suggest protective effects in moderate doses, but current evidence shows that there is no safe threshold for alcohol consumption for NAFLD. In fact, given the synergistic effect between alcohol consumption, obesity, and metabolic dysfunction, it is likely that alcohol use serves as a significant risk factor for the progression of liver disease in NAFLD and metabolic syndrome. This also affects the incidence of hepatocellular carcinoma. In this review, we summarize the overlapping pathophysiology of NAFLD and ALD, the current data on alcohol consumption in patients with NAFLD, and the effects of metabolic dysfunction and overweight in ALD.
Project description:Visceral obesity and metabolic syndrome are commonly associated with non-alcoholic fatty liver disease (NAFLD). The progression of steatosis to NASH depends on a number of metabolic and patient-related factors. The mechanisms of genetic predisposition towards the development of NASH and related fibrosis remain unclear. In this study, our aim was to utilize mitotyping and identify mitochondrial haplotypes that may be associated with NAFLD.We examined mitochondrial haplotypes along with patatin-like phospholipase domain containing 3 (PNPLA3) rs738409 genotype to determine their association with NAFLD phenotypes. Whole blood samples were obtained from 341 patients (BMI?>?35) undergoing weight reduction surgery after written consent. Liver biopsies were centrally reviewed by a single pathologist based on predetermined pathologic protocol (41.9 % Non-NASH NAFLD, 30.4 % NASH, 27.5 % controls). A 1,122 bp of the mitochondrial control loop was sequenced for each sample and classified into haplogroups.The presence of haplogroup L exhibits protection against the development of NASH and pericellular fibrosis. The alleles of PNPLA3 locus showed differential distribution in cohorts with NAFLD, NASH and pericellular fibrosis. Heterozygosity at this locus is independently associated with higher risk of having NASH and pericellular fibrosis.Mitochondrial genetics play an important role in NASH probably by modulation of oxidative stress and the efficiency of oxidative phosphorylation.
Project description:BACKGROUND:Alcohol dependence and long-term excessive alcohol use may cause liver damage, but only some patients develop cirrhosis. Similarly, high alcohol intake without evident liver disease often but not always produces abnormal enzymatic liver function tests (LFTs), particularly gamma-glutamyl transferase (GGT). We postulate that the factors predisposing to cirrhosis in alcoholics and to liver enzyme abnormality in drinkers are similar, and that biochemical LFTs could therefore be useful as markers of risk of alcoholic liver disease in excessive drinkers. METHODS:Data from participants in twin and twin-family studies on alcohol use and dependence were used to identify 1,003 people who had reported excessive alcohol intake (28 drinks or more per week). A total of 962 of these provided blood for biochemical tests at the same time. Body mass index (BMI) and biomarkers of metabolic syndrome, inflammation, and iron stores were used in logistic regression with abnormality in serum GGT, alanine aminotransferase (ALT), or aspartate aminotransferase (AST) as outcomes. We conducted genome-wide association analyses for GGT, ALT, and AST separately in the group reporting excessive alcohol intake (N = 951) and a low-intake group reporting 14 drinks or fewer per week (N = 8,716), and compared results. RESULTS:Abnormal GGT and ALT among excessive drinkers were associated with higher BMI, triglycerides, insulin, uric acid, C-reactive protein, ferritin, and transferrin saturation; and with lower high-density-lipoprotein cholesterol. Abnormal AST was associated with triglycerides, ferritin, and transferrin saturation. ALT was significantly associated with variants at reported genetic loci for alcoholic liver disease (PNPLA3, rs738409, p = 0.0076; TM6SF2, rs10401969, p = 0.0076; HSD17B13, rs10433879, p = 0.0024). CONCLUSIONS:Known risk factors for alcoholic cirrhosis including obesity and markers of metabolic syndrome, iron overload and inflammation are associated with liver enzyme abnormality in excessive drinkers.
Project description:Nonalcoholic fatty liver disease (NAFLD) includes a broad range of liver pathologies from simple steatosis to cirrhosis and fibrosis, in which a subtype accompanying hepatocyte degeneration and fibrosis is classified as nonalcoholic steatohepatitis (NASH). NASH accounts for approximately 10-30% of NAFLD and causes a higher frequency of liver-related death, and its progression of NASH has been considered to be complex involving multiple genetic factors interacting with the environment and lifestyle.To identify genetic factors related to NAFLD in the Japanese, we performed a genome-wide association study recruiting 529 histologically diagnosed NAFLD patients and 932 population controls. A significant association was observed for a cluster of SNPs in PNPLA3 on chromosome 22q13 with the strongest p-value of 1.4 × 10(-10) (OR = 1.66, 95%CI: 1.43-1.94) for rs738409. Rs738409 also showed the strongest association (p = 3.6 × 10(-6)) with the histological classifications proposed by Matteoni and colleagues based on the degree of inflammation, ballooning degeneration, fibrosis and Mallory-Denk body. In addition, there were marked differences in rs738409 genotype distributions between type4 subgroup corresponding to NASH and the other three subgroups (p = 4.8 × 10(-6), OR = 1.96, 95%CI: 1.47-2.62). Moreover, a subgroup analysis of NAFLD patients against controls showed a significant association of rs738409 with type4 (p = 1.7 × 10(-16), OR = 2.18, 95%CI: 1.81-2.63) whereas no association was obtained for type1 to type3 (p = 0.41). Rs738409 also showed strong associations with three clinical traits related to the prognosis of NAFLD, namely, levels of hyaluronic acid (p = 4.6 × 10(-4)), HbA1c (p = 0.0011) and iron deposition in the liver (p = 5.6 × 10(-4)).With these results we clearly demonstrated that Matteoni type4 NAFLD is both a genetically and clinically different subset from the other spectrums of the disease and that the PNPLA3 gene is strongly associated with the progression of NASH in Japanese population.