TM6SF2 Rs58542926 Research Articles

Ethnicity and Common Genetic Variants Modulate Nonalcoholic Fatty Liver Disease (NAFLD) Metabolic Phenotype in Obese Youth

Background: Pediatric Nonalcoholic Fatty Liver Disease (NAFLD) represents a major risk factor for insulin resistance and type 2 diabetes in adolescents. Methods: To characterize the clinical and genetic features associated with the development of pediatric NAFLD, 503 obese adolescents (191 Caucasians, 134 African Americans, and 178 Hispanics) underwent a MRI to quantify hepatic fat content, an oral glucose tolerance test to assess glucose tolerance and insulin sensitivity, and the genotyping of three SNPs associated with NAFLD (PNPLA3 rs738409, GCKR rs1260326, and TM6SF2 rs58542926). MRI and metabolic assessments were repeated in 133 patients after 2.27±1.44 years. Results: The prevalence of NAFLD was 42.9% in Caucasians, 15.7% in African Americans, and 59.6% in Hispanics (p<0.0001). Compared to Caucasians and Hispanics with NAFLD, African Americans adolescents with NAFLD had higher fasting glucose (p=0.03), insulin (p=0.0004), C-peptide (p=0.04), 2-h-glucose (p=0.04), HbA1c (p<0.0001), and lower insulin sensitivity (p=0.03), despite similar age (p=0.34) and gender distribution (p=0.37). This translated in a higher prevalence of prediabetes and type 2 diabetes in African Americans (66.6%) compared to Caucasians (24.4%) and Hispanics (31.1%) with NAFLD (p=0.0003). Analysis of the patients without NAFLD at baseline showed that ethnicity (p=0.02), high C-peptide levels (p=0.0006), changes in z-score BMI over time (p=0.0006) and common gene variants were strong predictors of NAFLD development at follow-up (AUROC curve 0.976). Conclusions: African American obese adolescents are relatively protected from NAFLD, but are more susceptible to the deleterious effects of NAFLD on glucose metabolism. The combination of ethnicity, markers of insulin resistance and genetic factors are strong predictors of pediatric NAFLD. Disclosure D. Trico: None. S. Caprio: None. G.R. Umano: None. A. Galderisi: None. M.M. Mata: None. J. Nouws: None. B. Pierpont: None. G. Kim: None. N. Santoro: None.

Prevalence and severity of nonalcoholic fatty liver disease by transient elastography: Genetic and metabolic risk factors in a general population.

The worldwide spread of obesity is leading to a dramatic increase in the prevalence of nonalcoholic fatty liver disease (NAFLD) and its complications. We aimed to evaluate both prevalence and factors associated with NAFLD in a general population in a Mediterranean area. We considered 890 consecutive individuals included in the community-based ABCD (Alimentazione, Benessere Cardiovascolare e Diabete) study (ISRCTN15840340). Controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) were measured with FibroScan. Participants were genotyped for PNPLA3 rs738409 and TM6SF2 rs58542926 variants. The prevalence of NAFLD in the cohort was 48%. NAFLD participants exhibited elevated LSM values, suggesting advanced fibrosis (6.5% of cases). Both NAFLD and advanced fibrosis were independently associated with traditional risk factors (NAFLD: age >50years, obesity, hypertension, elevated ALT and low HDL-cholesterol serum concentrations. Advanced fibrosis: IFG/diabetes, elevated ALT serum concentrations). A high prevalence (>60%) of NAFLD was found in obese people, while it varied widely in non-obese people according to the presence of metabolic risk factors. PNPLA3G variant (OR=1.33, 95% C.I.=1.01-1.8; P<.05) was independently associated with NAFLD. Prevalence of advanced fibrosis (high LSM values) ranged from 3.4% (no risk factors) to 60% (presence of all risk factors). TM6SF2 T variant (OR=3.06, 95% C.I.=1.08-8.65, P<.05) was independently associated with advanced fibrosis (high LSM values). In a cohort of a general population, the prevalence of NAFLD was very high, and among NAFLD patients a significant proportion had advanced fibrosis (high LSM values). Apart from traditional risk factors, genetic factors may have a significant role that needs to be further investigated.

Analysis of genotyping for predicting liver injury marker, procollagen III in persons at risk of non-alcoholic fatty liver disease.

Chronic liver disease presents a major global public health challenge. Stratification of asymptomatic, at-risk patients in primary care using non-invasive methods has the potential to address this by identifying those likely to progress. We, therefore, evaluated variant alleles at loci associated with non-alcoholic fatty liver disease as genetic determinants of substantial liver injury in patients with disease risk factors. Levels of serum procollagen III (PIIINP), an established fibrosis and steatohepatitis marker, were determined in 467 people who had type 2 diabetes and/or BMI>27.3 (identified from registration with general practitioners) in this observational cross-sectional study. Patients were genotyped for characterised risk alleles in PNPLA3 (rs738409), GCKR (rs1260326) and TM6SF2 (rs58542926) and associations with PIIINP assessed. The risk alleles in PNPLA3, GCKR or TM6SF2 were not found to be individually associated with the presence of a disease risk factor and were not significantly more common in patients with raised serum PIIINP. The prevalence of possession of both PNPLA3 and GCKR variant alleles combined was significantly higher in at-risk patients with clinically significant liver disease indicated by serum PIIINP above 11ng/mL (P=.014). Genotyping, therefore, has limited value for predicting severe liver disease in at-risk individuals identified in a community setting.

Fish intake interacts with TM6SF2 gene variant to affect NAFLD risk: results of a case-control study.

Non-alcoholic fatty liver disease (NAFLD) is a complex disease, resulting from a variety of genetic and environmental factors. The aim of this case-control study was to evaluate the effect of selected genetic polymorphisms, nutrition aspects and their interaction on the risk of NAFLD. The sample consisted of 134 patients with NAFLD and 217 controls. Disease was diagnosed by liver ultrasound and volunteers were clinically and nutritionally assessed. Food groups were extracted from a 172 food-item FFQ questionnaire. Three genetic polymorphisms were assessed: PNPLA3 rs738409, TM6SF2 rs58542926 and GCKR rs780094. We replicated the effect of previously reported risk factors for NAFLD, such as elevated liver enzymes, obesity and metabolic syndrome. Food groups rich in simple sugars, fat and especially saturated fat were positively associated with NAFLD risk, whereas food groups rich in polyunsaturated fatty acids were reversely associated with the possibility of developing the disease (p < 0.05). Only the PNPLA3 genetic variant was statistically significantly associated with the disease (padditive = 0.015). However, it was found that a one-portion increase in fish intake increased the risk of NAFLD in carriers of the risk allele of TM6SF2 rs58542926 polymorphism compared to non-carriers, after adjusting for age, gender, energy intake, pack-years, PAL, TM6SF2 genotype and fish consumption (ORdominant = 1.503, 95% CI 1.094-2.064). Fish intake exerts an additive effect on NAFLD risk for carriers of the TM6SF2 polymorphism. This novel finding provides further rationale on the need for personalized nutritional advice, based on the genetic background of NAFLD patients.

Evaluation of Polygenic Determinants of Non-Alcoholic Fatty Liver Disease (NAFLD) By a Candidate Genes Resequencing Strategy

NAFLD is a polygenic condition but the individual and cumulative contribution of identified genes remains to be established. To get additional insight into the genetic architecture of NAFLD, GWAS-identified GCKR, PPP1R3B, NCAN, LYPLAL1 and TM6SF2 genes were resequenced by next generation sequencing in a cohort of 218 NAFLD subjects and 227 controls, where PNPLA3 rs738409 and MBOAT7 rs641738 genotypes were also obtained. A total of 168 sequence variants were detected and 47 were annotated as functional. When all functional variants within each gene were considered, only those in TM6SF2 accumulate in NAFLD subjects compared to controls (P = 0.04). Among individual variants, rs1260326 in GCKR and rs641738 in MBOAT7 (recessive), rs58542926 in TM6SF2 and rs738409 in PNPLA3 (dominant) emerged as associated to NAFLD, with PNPLA3 rs738409 being the strongest predictor (OR 3.12, 95% CI, 1.8-5.5, P < 0.001). A 4-SNPs weighted genetic risk score value >0.28 was associated with a 3-fold increased risk of NAFLD. Interestingly, rs61756425 in PPP1R3B and rs641738 in MBOAT7 genes were predictors of NAFLD severity. Overall, TM6SF2, GCKR, PNPLA3 and MBOAT7 were confirmed to be associated with NAFLD and a score based on these genes was highly predictive of this condition. In addition, PPP1R3B and MBOAT7 might influence NAFLD severity.

The rs626283 Variant in the MBOAT7 Gene is Associated with Insulin Resistance and Fatty Liver in Caucasian Obese Youth.

Non alcoholic fatty liver disease (NAFLD) is a leading cause of liver damage in childhood, its occurrence is influenced by genetic and environmental factors. Recently, the rs626283 polymorphism in the MBOAT7 gene has been found to be associated with alcoholic liver disease and NAFLD in adults. In a multiethnic cohort of obese children and adolescents we genotyped the rs626283 polymorphism in the MBOAT7 gene, evaluated insulin sensitivity by an oral glucose tolerance test, and measured the intra-hepatic fat content (HFF%) by magnetic resonance imaging. In Caucasian youth, the minor allele (C) was associated with HFF% in (P=0.003), fasting insulin (P=0.03), area under the curve of glucose (P=0.03), and lower degree of whole-body insulin sensitivity (P=0.01) independent of age, gender, and body mass index z-score. A partial correlation showed that the association between the rs626283 variant and insulin resistance was driven by the presence of hepatic steatosis (P=0.009). However, there was no association between the rs626283 and hepatic steatosis among Hispanic and African American children and youth. The association between the rs626283 in the MBOAT7 gene among Caucasians was independent of the PNPLA3 rs738409, GCKR 1260326, and TM6SF2 rs58542926 (P=0.01). The four polymorphisms combined explained~19% of the HFF% in Caucasian obese children and adolescents. The rs626283 variant in the MBOAT7 gene is associated with NAFLD and may affect glucose metabolism by modulating intra-hepatic fat content in Caucasian obese children and adolescents.

Additive effects of PNPLA3 and TM6SF2 on the histological severity of non-alcoholic fatty liver disease.

We investigated the effects of PNPLA3 rs738409, TM6SF2 rs58542926, and MBOAT7-TMC4 rs641738 variants on metabolic phenotypes and their combined effects on the histological severity of non-alcoholic fatty liver disease (NAFLD). We genotyped rs738409, rs58542926, and rs641738 in biopsy-proven NAFLD patients (n=416) and healthy controls (n=109). Homeostasis model assessment of insulin resistance and adipose tissue insulin resistance were calculated. The rs738409 and rs58542926 variants, but not rs641738, were associated not only with non-alcoholic steatohepatitis (NASH) (odds ratio [OR], 2.00; 95% confidence interval [CI], 1.46-2.73 and OR, 1.91; 95% CI, 1.04-3.51) but also with significant fibrosis (≥F2) (OR, 1.53; 95% CI, 1.11-2.11 and OR, 1.88; 95% CI, 1.02-3.46) in NAFLD, even after adjustment for metabolic risk factors. Of both variants, only rs738409 was associated with homeostasis model assessment of insulin resistance and adipose tissue insulin resistance even in healthy controls (P=0.046 and 0.002, respectively) as well as in the entire study cohort (P=0.016 and 0.048, respectively). PNPLA3 and TM6SF2 risk variants additively increased the risk of NASH and significant fibrosis (OR per risk allele, 2.03; 95% CI, 1.50-2.73 and 1.61; 95% CI, 1.19-2.17). Even in subjects with low insulin resistance, the risk of NASH or significant fibrosis increased as the number of risk alleles increased (P=0.008 and 0.020, respectively). PNPLA3 and TM6SF2 determine the risk of NASH and significant fibrosis, even after adjustment for insulin resistance, and exert an additive effect on NASH and significant fibrosis.

Genetic determinants of hepatic steatosis and serum cytokeratin-18 fragment levels in Taiwanese children.

There are substantial genetic components contributing to the susceptibility of nonalcoholic fatty liver disease (NAFLD). It has recently been reported that the rs641738 C>T variant in the membrane-bound O-acyltransferase domain-containing protein 7 (MBOAT7) gene increased severity of NAFLD in adults of European descent. We aimed to test the hypothesis that MBOAT7 rs641738 variant would increase hepatic steatosis and hepatocellular injury in obese children. A total of 831 obese children aged 7-15years were recruited. Hepatic steatosis was measured by ultrasonography. Because PNPLA3 rs738409, GCKR rs780094 and TM6SF2 rs58542926 variants are known to confer susceptibility to NAFLD, we assessed the influence of MBOAT7 rs641738 on hepatic steatosis, and serum levels of CK-18 fragment (a biomarker of hepatocellular injury and apoptosis for NAFLD) after adjusting the effects of PNPLA3, GCKR and TM6SF2 polymorphisms. Of the recruited obese children, 22.7% had hepatic steatosis. PNPLA3 rs738409, GCKR rs780094 and TM6SF2 rs58542926 variants were independent risk factors of hepatic steatosis and elevated ALT levels. In contrast, MBOAT7 rs641738 variants, neither heterozygous nor homozygous genotypes, were not associated with hepatic steatosis, insulin resistance, lipid levels and liver enzymes. The multiple linear regression model revealed that after adjusting for age, gender, body mass index z score, PNPLA3 rs738409 and GCKR rs780094 variants, but not MBOAT7 rs641738, were associated with serum levels of CK-18 fragment. The variant MBOAT7 rs641738 genotype is not associated with hepatic steatosis and serum levels of CK-18 fragment in obese Taiwanese children.

Combining Genetic Variants to Improve Risk Prediction for NAFLD and Its Progression to Cirrhosis: A Proof of Concept Study.

Background & Aims Identifying NAFLD patients at risk of progression is crucial to orient medical care and resources. We aimed to verify if the effects determined by different single nucleotide polymorphisms (SNPs) could add up to multiply the risk of NAFLD and NASH-cirrhosis. Methods Three study populations, that is, patients diagnosed with NASH-cirrhosis or with noncirrhotic NAFLD and healthy controls, were enrolled. PNPLA3 rs738409, TM6SF2 rs58542926, KLF6 rs3750861, SOD2 rs4880, and LPIN1 rs13412852 were genotyped. Results One hundred and seven NASH-cirrhotics, 93 noncirrhotic NAFLD, and 90 controls were enrolled. At least one difference in allele frequency between groups was significant, or nearly significant, for the PNPLA3, TM6SF2, and KLF6 variants (p < 0.001, p < 0.05, and p = 0.06, resp.), and a risk score based on these SNPs was generated. No differences were observed for SOD2 and LPIN1 SNPs. When compared to a score of 0, a score of 1-2 quadrupled, and a score of 3-4 increased 20-fold the risk of noncirrhotic NAFLD; a score of 3-4 quadrupled the risk of NASH-cirrhosis. Conclusions The effects determined by disease-associated variants at different loci can add up to multiply the risk of NAFLD and NASH-cirrhosis. Combining different disease-associated variants may represent the way for genetics to keep strength in NAFLD diagnostics.

Significant positive association of endotoxemia with histological severity in 237 patients with non-alcoholic fatty liver disease.

Patients with nonalcoholic steatohepatitis (NASH) have gut dysbiosis and intestinal bacterial overgrowth. To test the hypothesis that endotoxemia is associated with the histological severity of nonalcoholic fatty liver disease (NAFLD) and determine factors associated with endotoxemia. The endotoxemia markers lipopolysaccharide-binding protein (LBP) and endotoxin levels were measured in 237 NAFLD patients 1day before liver biopsy. Biomarkers of liver injury and transient elastography were performed as additional markers of disease severity. A total of 114/237 (48%) patients had NASH and 80/237 (34%) had F2-4 fibrosis. LBP was correlated with lobular inflammation (P=.001), while both LBP (P=.0004) and endotoxin levels (P=0.008) were correlated with fibrosis. LBP was also correlated with cytokeratin-18 fragments (P=.002) and aspartate aminotransferase-to-alanine aminotransferase ratio (P=.006), and both LBP (P=.019) and endotoxin (P=.006) were correlated with liver stiffness measurement by transient elastography. LBP was increased in patients with NASH (15.3±4.6 vs 13.8±3.3μg/mL; P=.005) and F2-4 fibrosis (15.4±4.4 vs 14.0±3.7μg/mL; P=.008). Interestingly, patients harbouring the TM6SF2 rs58542926 T allele that predispose to NAFLD/NASH had higher LBP level. By multivariate analysis, gender, higher body mass index and glycated haemoglobin, and TM6SF2 variants were independent factors associated with increased LBP level. Endotoxemia is positively associated with NASH and significant fibrosis. The association between TM6SF2 and endotoxemia warrants further investigations. The findings may shed light on the pathogenesis of NASH and inform a novel treatment target.

Combined effects of the PNPLA3 rs738409, TM6SF2 rs58542926, and MBOAT7 rs641738 variants on NAFLD severity: a multicenter biopsy-based study

The PNPLA3 p.I148M, TM6SF2 p.E167K, and MBOAT7 rs641738 variants represent genetic risk factors for nonalcoholic fatty liver disease (NAFLD). Here we investigate if these polymorphisms modulate both steatosis and fibrosis in patients with NAFLD. We recruited 515 patients with NAFLD (age 16-88 years, 280 female patients). Liver biopsies were performed in 320 patients. PCR-based assays were used to genotype the PNPLA3, TM6SF2, and MBOAT7 variants. Carriers of the PNPLA3 and TM6SF2 risk alleles showed increased serum aspartate aminotransferase and alanine transaminase activities (P < 0.05). The PNPLA3 genotype was associated with steatosis grades S2-S3 (P < 0.001) and fibrosis stages F2-F4 (P < 0.001). The TM6SF2 genotype was associated with steatosis (P = 0.003) but not with fibrosis (P > 0.05). The MBOAT7 variant was solely associated with increased fibrosis (P = 0.046). In the multivariate model, variants PNPLA3 (P = 0.004) and TM6SF2 (P = 0.038) were associated with steatosis. Fibrosis stages were affected by the PNPLA3 (P = 0.042) and MBOAT7 (P = 0.021) but not by the TM6SF2 polymorphism (P > 0.05). The PNPLA3, TM6SF2, and MBOAT7 variants are associated with increased liver injury. The TM6SF2 variant seems to modulate predominantly hepatic fat accumulation, whereas the MBOAT7 polymorphism is linked to fibrosis. The PNPLA3 polymorphism confers risk of both increased steatosis and fibrosis.

Regional differences in genetic susceptibility to non-alcoholic liver disease in two distinct Indian ethnicities.

AIMTo validate the association of variants in PNPLA3 (rs2281135) and TM6SF2 (rs58542926) genes with ultrasound detected non-alcoholic fatty liver disease (NAFLD).METHODSA total of 503 individuals with and without fatty infiltration were recruited. Fatty infiltration was confirmed based on ultrasound findings. Anthropometric data and blood samples were collected from the study group. DNA was isolated from peripheral blood, quality and quantity was assessed by gel electrophoresis and spectrophotometer respectively. Genotyping of the variants in PNPLA3 and TM6SF2 genes was carried out by employing taqman probes (C_15875080_10 for PNPLA3 and C_8946351_10 for TM6SF2 SNP) on real time PCR (Stepone-Lifetechnologies). Genotype data was tested for deviations from Hardy-Weinberg equilibrium. χ2 test was used to analyze the statistical significance of the difference in genotype distribution of the studied variants in patients and controls and the strength of association was expressed as odds ratio (95%CI). A two-tailed P value of ≤ 0.05 was considered statistically significant.RESULTSThe study group comprised of 503 individuals of which 256 had fatty infiltration and 247 without fatty infiltration and thus formed the patient and control groups respectively. As the patient group could be divided in to two distinct ethnicities (ancestral South Indians-ASI and North-East Indians-NEI), further recruitment of control cohort and association analyses was carried out based on ethnicities. Of the 256 with fatty infiltration 93 were ASI and 163 were NEI and of the 247 controls 138 were ASI and 109 were NEI. As expected, there were significant differences in the anthropometric and other clinical data between the control and the patient groups. However significant differences within the ethnicities were also noted. While rs2281135 in PNPLA3 gene was significantly associated (P = 0.03) with higher risk (odds 1.9, 95%CI: 1.5-3.14, P = 0.03) of NAFLD in NEI ethnicity, rs58542926 in TM6SF2 gene was significantly associated with NAFLD with a 2.7 fold higher risk (odds 2.7, 95%CI: 1.37-5.3, P = 0.0004) of the disease. There were significantly higher proportions of individuals with variants in both the genes in the patient group in both ASI (patients - 14/93 and controls - 7/138; P = 0.009) and NEI ethnicities (patients - 17/163 and controls - 7/109; P = 0.01).CONCLUSIONAlthough the study identified distinct genetic susceptibility in the two ethnicities, transheterozygosity of the variants suggests higher risk of NAFLD in individuals with both the variants.

Additive Effects of the Risk Alleles of PNPLA3 and TM6SF2 on Non-alcoholic Fatty Liver Disease (NAFLD) in a Chinese Population.

Recent genome-wide association studies have identified that variants in or near PNPLA3, NCAN, GCKR, LYPLAL1, and TM6SF2 are significantly associated with non-alcoholic fatty liver disease (NAFLD) in multiple ethnic groups. Studies on their impact on NAFLD in Han Chinese are still limited. In this study, we examined the relevance of these variants to NAFLD in a community-based Han Chinese population and further explored their potential joint effect on NAFLD. Six single nucleotide polymorphisms (SNPs) (PNPLA3 rs738409, rs2294918, NCAN rs2228603, GCKR rs780094, LYPLAL1 rs12137855, and TM6SF2 rs58542926) previously identified in genome-wide analyses, to be associated with NAFLD were genotyped in 384 NAFLD patients and 384 age- and gender-matched healthy controls. We found two out of the six polymorphisms, PNPLA3 rs738409 (OR = 1.52, 95%CI: 1.19–1.96; P = 0.00087) and TM6SF2 rs58542926 (OR = 2.11, 95%CI: 1.34–3.39; P = 0.0016) are independently associated with NAFLD after adjustment for the effects of age, gender, and BMI. Our analysis further demonstrated the strong additive effects of the risk alleles of PNPLA3 and TM6SF2 with an overall significance between the number of risk alleles and NAFLD (OR = 1.64, 95%CI: 1.34–2.01; P = 1.4 × 10-6). The OR for NAFLD increased in an additive manner, with an average increase in OR of 1.52 per additional risk allele. Our results confirmed that the PNPLA3 and TM6SF2 variants were the most significant risk alleles for NAFLD in Chinese population. Therefore, genotyping these two genetic risk factors may help identify individuals with the highest risk of NAFLD.

Variants in the autophagy-related gene IRGM confer susceptibility to non-alcoholic fatty liver disease by modulating lipophagy

Autophagy has been shown to be crucial in the regulation of the intracellular lipid stores in hepatocytes. We hypothesize that immunity-related GTPase family M (IRGM) gene (an autophagy-related gene) variants confer the susceptibility to non-alcoholic fatty liver disease (NAFLD) development. 832 obese children and adolescents aged 6-18years were recruited. NAFLD was determined by liver ultrasonography. We genotyped PNPLA3 rs738409, GCKR rs780094, TM6SF2 rs58542926, six IRGM single nucleotide polymorphisms (rs13361189, rs9637876, rs72553867, rs10065172, rs1000113, and rs11747270). To understand the molecular mechanism, we examined the effects of IRGM knockdown and overexpression on autophagic flux and lipid droplet metabolism in human hepatoma cells. 22.8% of recruited obese children and adolescents had NAFLD. Multiple logistic regression analysis revealed that after controlling for the effects of age- and gender-adjusted body mass index, gender, PNPLA3, GCKR, and TM6SF2 polymorphisms, variant IRGM rs10065172 TT genotype independently increased the odds ratio of NAFLD by 2.04 (95% confidence interval 1.22-3.42; p=0.007), as compared to the CC genotype. The predictive model was validated by means of 10-fold cross validation. Functional assay revealed that IRGM knockdown inhibited autophagic flux and increased lipid droplet content in HepG2 and PLC/PRF/5 cells, which were reversed by the autophagy inducer rapamycin administration. Similarly, wortmannin (an autophagy inhibitor) increased intracellular lipid droplet content. In contrast, overexpression of IRGM caused decreased lipid droplet content in HepG2 cells. Our findings suggest that IRGM may contribute to the development of human NAFLD by altering hepatic lipid metabolism through the autophagy pathway. Autophagy is involved in the process of lipid metabolism in hepatocytes. The mechanism of autophagy regulation by IRGM has just been unveiled. This study demonstrates that genetic variants in IRGM confer risk of human non-alcoholic fatty liver disease. The functional studies reveal how IRGM regulates hepatic lipid droplet content.

Association of PNPLA3 rs738409 and TM6SF2 rs58542926 with health services utilization in a population-based study.

BackgroundHepatic steatosis confers an increased risk of metabolic and cardiovascular disease and higher health services use. Associations of the single nucleotide polymorphisms (SNP) PNPLA3 rs738409 and TM6SF2 rs58542926 with hepatic steatosis have recently been established. This study investigates the association between rs738409 and rs58542926 with health services utilization in a general population.MethodsData of 3759 participants from Study of Health in Pomerania (SHIP), a population-based study in Germany, were obtained. The annual number of outpatient visits, hospitalization and length of hospital stay was regressed on rs738409 and rs58542926 and adjusted for socio-economic factors, lifestyle habits, clinical factors, and health status.ResultsMinor allele homozygous subjects of rs738409 had an increased odds of hospitalization as compared to major allele homozygous subjects (odds ratio [OR] 1.51; 95 % confidence interval [CI], 1.02 to 2.15). Heterozygous subjects did not differ from major allele homozygous subjects with respect to their odds of hospitalization. The three genotype groups of rs738409 were similar with respect to the number of outpatient visits and inpatient days. Minor allele homozygous and heterozygous subjects of rs58542926 had higher outpatient utilization (+53.04 % and +67.56 %, p < 0.05, respectively) and inpatient days than major allele homozygous subjects.ConclusionsAfter adjustment for several confounding factors, PNPLA3 rs738409 and TM6SF2 rs58542926 were associated with the number of outpatient visits, hospitalization, and inpatient days. Further studies are warranted to replicate our findings and to evaluate whether genetic data can be used to identify subjects with excess health services utilization.

Relationships between Genetic Variations of PNPLA3, TM6SF2 and Histological Features of Nonalcoholic Fatty Liver Disease in Japan.

Background/AimsIt is important to determine the noninvasive parameters of histological features in nonalcoholic fatty liver disease (NAFLD). The aim of this study was to investigate the value of genetic variations as surrogate markers of histological features.MethodsThe parameters that affected the histological features of NAFLD were investigated in 211 Japanese patients with biopsy-proven NAFLD. The relationships between genetic variations in PNPLA3 rs738409 or TM6SF2 rs58542926 and histological features were analyzed. Furthermore, the impact of genetic variations that affected the pathological criteria for the diagnosis of nonalcoholic steatohepatitis (NASH) (Matteoni classification and NAFLD activity score) was evaluated.ResultsThe fibrosis stage of PNPLA3 GG was significantly more progressive than that of CG by multiple comparisons. Multivariate analysis identified PNPLA3 genotypes as predictors of fibrosis of stage 2 or more, but the impact tended to decrease at stage 3 or greater. There were no significant differences among the histological features of the three genotypes of TM6SF2. PNPLA3 genotypes partly affected the definition of NASH by the NAFLD activity score, but TM6SF2 genotypes did not affect the definition of NASH.ConclusionsIn Japanese patients with biopsy-proven NAFLD, PNPLA3 genotypes may partly affect histological features, including stage of fibrosis, but the TM6SF2 genotype does not affect histological features.

PNPLA3 rs738409 and TM6SF2 rs58542926 variants increase the risk of hepatocellular carcinoma in alcoholic cirrhosis

BackgroundPNPLA3 rs738409 polymorphism is associated with fatty liver disease, alcoholic or non-alcoholic (NAFLD) and hepatocellular carcinoma (HCC). TM6SF2 rs58542926 is clearly associated with NAFLD, but it is not clearly associated with HCC. The relationship between TM6SF2 rs58542926 and HCC and the potential synergistic effect of TM6SF2 and PNPLA3 variants in modifying the risk of HCC are not known. AimThis study assessed the interaction between PNPLA3 rs738409 and TM6SF2 rs58542926 variants in the conditioning of HCC development. MethodsA total of 511 cirrhotic patients (44% alcohol-related, 56% viral, 57.5% liver transplanted) were retrospectively investigated for HCC occurrence. PNPLA3 rs734809 and TM6SF2 rs58542926 were genotyped using restriction fragment length polymorphism and real-time allelic discrimination polymerase chain reaction methods. ResultsPatients with HCC were more likely to be PNPLA3 rs734809 G/G homozygotes (41/150 vs. 60/361, p=0.009) or TM6SF2 rs58542926 C/T-T/T (27/150 vs. 41/361, p=0.044). The presence of either PNPLA3 G/G or TM6SF2*/T identified high-risk genotypes for HCC, which were strongly associated with HCC (64/150 vs. 93/361, p=0.0002). This association was evident in alcohol-related (p=0.0007) but not in viral cirrhosis. ConclusionTM6SF2 C/T or T/T in conjunction with PNPLA3 G/G variants may be potential genetic risk factors for developing HCC in alcohol-related cirrhosis.

TM6SF2 rs58542926 is not associated with steatosis and fibrosis in largecohort of patients with genotype 1 chronic hepatitis C.

We tested the putative association of the rs58542926 variant of TM6SF2, a recently described genetic determinant of nonalcoholic fatty liver disease, with steatosis and fibrosis in genotype 1(G1) chronic hepatitis C(CHC) patients. A total of 694 consecutively biopsied Caucasian G1 CHC patients were genotyped for TM6SF2 rs58542926, IL28B rs12979860 and PNPLA3 rs738409. Steatosis was classified as absent (<5%), mild-moderate(5-29%) and severe(≥30%), Fibrosis was considered severe if=F3-F4. Carriers of TM6SF2 rs58542926 (6.3% of patients) exhibited lower serum levels of cholesterol (P = 0.04) and triglycerides (P = 0.01), but a similar distribution of steatosis severity (P = 0.63), compared to noncarriers. Prevalence and severity of steatosis were reduced in IL28B C allele carriers (P = 0.005) and elevated in PNPLA3 G allele carriers (P < 0.001). After adjustment for age, gender, body mass index and homoeostasis model assessment score, steatosis severity was independently associated with IL28B rs12979860 (odds ratio [OR] 0.69, 95% confidence interval [CI] 0.55-0.86, P = 0.001) and PNPLA3 rs738409 (OR 1.84, 95% CI 1.46-2.83, P < 0.001), but not TM6SF2 rs58542926 (OR 1.48, 95% CI 0.82-2.69, P = 0.19). Variants of TM6SF2 (30.9% vs. 25%, P = 0.40), IL28B and PNPLA3 were not directly associated with fibrosis severity, although variants of IL28B and PNPLA3 promoted steatosis (OR 1.36, 95% CI 1.06-1.75, P = 0.01) that in turn is associated with severe fibrosis. In G1 CHC patients, TM6SF2 rs58542926 does not affect the histological severity of liver damage. However, IL28B rs12979860 and PNPLA3 rs738409 modify steatosis.

TM6SF2 rs58542926 influences hepatic fibrosis progression in patients with non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is an increasingly common condition, strongly associated with the metabolic syndrome, that can lead to progressive hepatic fibrosis, cirrhosis and hepatic failure. Subtle inter-patient genetic variation and environmental factors combine to determine variation in disease progression. A common non-synonymous polymorphism in TM6SF2 (rs58542926 c.449 C>T, p.Glu167Lys) was recently associated with increased hepatic triglyceride content, but whether this variant promotes clinically relevant hepatic fibrosis is unknown. Here we confirm that TM6SF2 minor allele carriage is associated with NAFLD and is causally related to a previously reported chromosome 19 GWAS signal that was ascribed to the gene NCAN. Furthermore, using two histologically characterized cohorts encompassing steatosis, steatohepatitis, fibrosis and cirrhosis (combined n=1,074), we demonstrate a new association, independent of potential confounding factors (age, BMI, type 2 diabetes mellitus and PNPLA3 rs738409 genotype), with advanced hepatic fibrosis/cirrhosis. These findings establish new and important clinical relevance to TM6SF2 in NAFLD.