Association of Genetic Variation With Cirrhosis: A Multi-Trait Genome-Wide Association and Gene-Environment Interaction Study

PNPLA3 risk allele is associated with risk of hepatocellular carcinoma but not decompensation in compensated cirrhosis

BACKGROUND

The PNPLA3-rs738409-G, TM6SF2-rs58542926-T, and HSD17B13-rs6834314-A polymorphisms have been associated with cirrhosis, hepatic decompensation, and HCC. However, whether they remain associated with HCC and decompensation in people who already have cirrhosis remains unclear, which limits the clinical utility of genetics in risk stratification as HCC is uncommon in the absence of cirrhosis. We aimed to characterize the effects of PNPLA3, TM6SF2, and HSD17B13 genotype on hepatic decompensation, HCC, and liver-related mortality or liver transplant in patients with baseline compensated cirrhosis.

METHODS

We conducted a single-center retrospective study of patients in the Michigan Genomics Initiative who underwent genotyping. The primary predictors were PNPLA3, TM6SF2, and HSD17B13 genotypes. Primary outcomes were either hepatic decompensation, HCC, or liver-related mortality/transplant. We conducted competing risk Fine-Gray analyses on our cohort.

RESULTS

We identified 732 patients with baseline compensated cirrhosis. During follow-up, 50% of patients developed decompensation, 13% developed HCC, 24% underwent liver transplant, and 27% died. PNPLA3-rs738409-G genotype was associated with risk of incident HCC: adjusted subhazard hazard ratio 2.42 (1.40-4.17), p=0.0015 for PNPLA3-rs738409-GG vs. PNPLA3-rs738409-CC genotype. The 5-year cumulative incidence of HCC was higher in PNPLA3-rs738409-GG carriers than PNPLA3-rs738409-CC/-CG carriers: 15.6% (9.0%-24.0%) vs. 7.4% (5.2%-10.0%), p<0.001. PNPLA3 genotype was not associated with decompensation or the combined outcome of liver-related mortality or liver transplant. TM6SF2 and HSD17B13 genotypes were not associated with decompensation or HCC.

CONCLUSIONS

The PNPLA3-rs738409-G allele is associated with an increased risk of HCC among patients with baseline compensated cirrhosis. People with cirrhosis and PNPLA3-rs738409-GG genotype may warrant more intensive HCC surveillance.

Integrating genetic and socioeconomic data to predict the progression of nonalcoholic fatty liver disease

OBJECTIVES

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease globally, with an estimated prevalence exceeding 25%. Variants in the PNPLA3 and HSD17B13 genes have been a focus of investigations surrounding the etiology and progression of NAFLD and are believed to contribute to a greater burden of disease experienced by Hispanic Americans. However, little is known about socioeconomic factors influencing NAFLD progression or its increased prevalence among Hispanics.

MATERIALS AND METHODS

We cross-sectionally analyzed 264 patients to assess the role of genetic and socioeconomic variables in the development of advanced liver fibrosis in individuals at risk for NAFLD.

RESULTS

Adjusting for age, sex, body mass index, and PNPLA3 genotype, lacking a college degree was associated with 3.3 times higher odds of advanced fibrosis (95% confidence interval [CI]: 1.21-8.76, p = 0.019), an effect comparable to that of possessing the major PNPLA3 risk variant. Notably, the effect of PNPLA3 genotype on advanced fibrosis was attenuated to nonsignificance following adjustment for education and other socioeconomic markers. The effect of the protective HSD17B13 variant, moreover, diminished after adjustment for education (odds ratio [OR]: 0.39 [95% CI: 0.13-1.16, p = 0.092]), while lower education continued to predict advanced fibrosis following multivariable adjustment with an OR of 8.0 (95% CI: 1.91-33.86, p = 0.005).

DISCUSSION

Adjusting for education attenuated the effects of genotype and Hispanic ethnicity on liver fibrosis, suggesting that social factors-rather than genes or ethnicity-may be driving disease severity within some populations. Findings reveal the importance of including socioenvironmental controls when considering the role of genetics or ethnicity in complex disease.

Integrative common and rare variant analyses provide insights into the genetic architecture of liver cirrhosis

We report a multi-ancestry genome-wide association study on liver cirrhosis and its associated endophenotypes, alanine aminotransferase (ALT) and γ-glutamyl transferase. Using data from 12 cohorts, including 18,265 cases with cirrhosis, 1,782,047 controls, up to 1 million individuals with liver function tests and a validation cohort of 21,689 cases and 617,729 controls, we identify and validate 14 risk associations for cirrhosis. Many variants are located near genes involved in hepatic lipid metabolism. One of these, PNPLA3 p.Ile148Met, interacts with alcohol intake, obesity and diabetes on the risk of cirrhosis and hepatocellular carcinoma (HCC). We develop a polygenic risk score that associates with the progression from cirrhosis to HCC. By focusing on prioritized genes from common variant analyses, we find that rare coding variants in GPAM associate with lower ALT, supporting GPAM as a potential target for therapeutic inhibition. In conclusion, this study provides insights into the genetic underpinnings of cirrhosis.

Metabolic dysfunction-associated steatotic liver disease: Update and impact of new nomenclature on the American Association for the Study of Liver Diseases practice guidance on nonalcoholic fatty liver disease

This commentary discusses how clinicians and various stakeholders can utilize the recently published American Association for the Study of Liver Diseases nonalcoholic fatty liver disease (AASLD NAFLD) Practice Guidance in light of the change in the nomenclature to steatotic liver disease and its subcategories. The new terminologies explained in this commentary make it easier for the readers to interchangeably use metabolic dysfunction-associated steatotic liver disease (MASLD) in place of NAFLD and metabolic-dysfunction associated steatohepatitis (MASH) instead of nonalcoholic steatohepatitis (NASH), respectively, as they read the NAFLD Practice Guidance. The guidance document is relevant and can be utilized for the diagnosis, risk stratification, and management of patients with MASLD. This commentary serves as an accompanying article to the NAFLD Practice Guidance and helps it clinical application in the light of the new nomenclature.

Inhibition of sodium-glucose cotransporter-2 and liver-related complications in individuals with diabetes: a Mendelian randomization and population-based cohort study

BACKGROUND AND AIMS

No medication has been found to reduce liver-related events. We evaluated the effect of sodium-glucose cotransporter-2 inhibitor (SGLT2i) on liver-related outcomes.

APPROACH AND RESULTS

Single nucleotide polymorphisms associated with SGLT2 inhibition were identified, and a genetic risk score (GRS) was computed using the UK Biobank data (n=337,138). Two-sample Mendelian randomization (MR) was conducted using the FinnGen (n=218,792) database and the UK Biobank data. In parallel, a nationwide population-based study using the Korean National Health Insurance Service (NHIS) database was conducted. The development of liver-related complications (ie, hepatic decompensation, HCC, liver transplantation, and death) was compared between individuals with type 2 diabetes mellitus and steatotic liver diseases treated with SGLT2i (n=13,208) and propensity score-matched individuals treated with dipeptidyl peptidase-4 inhibitor (n=70,342). After computing GRS with 6 single nucleotide polymorphisms (rs4488457, rs80577326, rs11865835, rs9930811, rs34497199, and rs35445454), GRS-based MR showed that SGLT2 inhibition (per 1 SD increase of GRS, 0.1% lowering of HbA1c) was negatively associated with cirrhosis development (adjusted odds ratio=0.83, 95% CI=0.70-0.98, p =0.03) and this was consistent in the 2-sample MR (OR=0.73, 95% CI=0.60-0.90, p =0.003). In the Korean NHIS database, the risk of liver-related complications was significantly lower in the SGLT2i group than in the dipeptidyl peptidase-4 inhibitor group (adjusted hazard ratio=0.88, 95% CI=0.79-0.97, p =0.01), and this difference remained significant (adjusted hazard ratio=0.72-0.89, all p <0.05) across various sensitivity analyses.

CONCLUSIONS

Both MRs using 2 European cohorts and a Korean nationwide population-based cohort study suggest that SGLT2 inhibition is associated with a lower risk of liver-related events.

Relationship among serum 25-hydroxyvitamin D, fibrosis stage, genetic susceptibility, and risk of severe liver disease

OBJECTIVES

The prospective association between vitamin D and new-onset severe liver disease is still uncertain. The aim of this study was to assess the association of serum 25-hydroxyvitamin D (25(OH)D) with new-onset severe liver disease and to evaluate whether fibrosis stage, as assessed by the fibrosis- 4 (FIB-4) scores and genetic risk for liver cirrhosis may modify this association.

METHODS

The study included 439 807 participants without liver diseases at baseline from the UK Biobank. Serum 25(OH)D concentrations were measured using the chemiluminescent immunoassay method. The primary outcome was new-onset severe liver disease, a composite definition of compensated or decompensated liver cirrhosis, liver failure, hepatocellular carcinoma, and liver-related death.

RESULTS

During a median follow-up of 12 y, 4510 participants developed new-onset severe liver disease. Overall, there was an inverse association of serum 25(OH)D with new-onset severe liver disease (per SD increment, adjusted hazard ratio [HR], 0.87; 95% confidence interval, 0.84-0.91). Similarly, serum 25(OH)D (per SD increment) was significantly and inversely associated with new-onset compensated cirrhosis, decompensated cirrhosis, liver failure, and liver-related death, respectively, with HRs ranging from 0.75 to 0.87. No significant association was found for hepatocellular carcinoma. Furthermore, there was a stronger inverse association between serum 25(OH)D and severe liver disease among those with a higher FIB-4 score (≥2.67, 1.3 to <2.67, and <1.3; Pinteraction < 0.001). However, the genetic risks for liver cirrhosis, calculated using 12 related single nucleotide polymorphisms, did not significantly modify the association between serum 25(OH)D and severe liver disease (Pinteraction = 0.216).

CONCLUSIONS

Lower serum 25(OH)D concentrations were significantly associated with a greater risk for new-onset severe liver disease, especially in participants with higher FIB-4 scores.

Genome-wide association study identifies high-impact susceptibility loci for HCC in North America

BACKGROUND AND AIMS

Despite the substantial impact of environmental factors, individuals with a family history of liver cancer have an increased risk for HCC. However, genetic factors have not been studied systematically by genome-wide approaches in large numbers of individuals from European descent populations (EDP).

APPROACH AND RESULTS

We conducted a 2-stage genome-wide association study (GWAS) on HCC not affected by HBV infections. A total of 1872 HCC cases and 2907 controls were included in the discovery stage, and 1200 HCC cases and 1832 controls in the validation. We analyzed the discovery and validation samples separately and then conducted a meta-analysis. All analyses were conducted in the presence and absence of HCV. The liability-scale heritability was 24.4% for overall HCC. Five regions with significant ORs (95% CI) were identified for nonviral HCC: 3p22.1, MOBP , rs9842969, (0.51, [0.40-0.65]); 5p15.33, TERT , rs2242652, (0.70, (0.62-0.79]); 19q13.11, TM6SF2 , rs58542926, (1.49, [1.29-1.72]); 19p13.11 MAU2 , rs58489806, (1.53, (1.33-1.75]); and 22q13.31, PNPLA3 , rs738409, (1.66, [1.51-1.83]). One region was identified for HCV-induced HCC: 6p21.31, human leukocyte antigen DQ beta 1, rs9275224, (0.79, [0.74-0.84]). A combination of homozygous variants of PNPLA3 and TERT showing a 6.5-fold higher risk for nonviral-related HCC compared to individuals lacking these genotypes. This observation suggests that gene-gene interactions may identify individuals at elevated risk for developing HCC.

CONCLUSIONS

Our GWAS highlights novel genetic susceptibility of nonviral HCC among European descent populations from North America with substantial heritability. Selected genetic influences were observed for HCV-positive HCC. Our findings indicate the importance of genetic susceptibility to HCC development.

How does alcohol use impact morbidity and mortality of liver cirrhosis? A systematic review and dose-response meta-analysis

BACKGROUND

Alcohol consumption is the most important risk factor responsible for the disease burden of liver cirrhosis (LC). Estimates of risk relationships available usually neither distinguish between different causes such as alcohol-related LC or hepatitis-related LC, nor differentiate between morbidity and mortality as outcome. We aimed to address this research gap and identify dose-response relationships between alcohol consumption and LC, by cause and outcome.

METHODS

A systematic review using PubMed/Medline and Embase was conducted, identifying studies that reported an association between level of alcohol use and LC. Meta-regression models were used to estimate the dose-response relationships and control for heterogeneity.

RESULTS

Totally, 44 studies, and 1 secondary data source, with a total of 5,122,534 participants and 15,150 cases were included. Non-linear dose-response relationships were identified, attenuated for higher levels of consumption. For morbidity, drinking 25 g/day was associated with a RR of 1.81 (95% CI 1.68-1.94) compared to lifetime abstention; 50 g/day and 100 g/day corresponded to 3.54 (95% CI 3.29-3.81) and 8.15 (95% CI 7.46-8.91), respectively. For mortality, for 25 g/day, a RR of 2.65 (95% CI 2.22-3.16); for 50 g/day, a RR of 6.83 (95% CI 5.84-7.97); for 100 g/day, a RR of 16.38 (95% CI 13.81-19.42) were identified. A higher risk for alcohol-related and all-cause LC as compared to hepatitis C-related LC was found.

CONCLUSION

Our results demonstrated higher acceleration for mortality compared to morbidity. The current findings will inform the way we quantify the burden due to LC attributable to alcohol use.

Effect of donor HSD17B13 genotype on patient survival after liver transplant: a retrospective cohort study

Background

Several genetic variants are associated with chronic liver disease. The role of these variants in outcomes after liver transplantation (LT) is uncertain. The aim of this study was to determine if donor genotype at risk-associated variants in PNPLA3 (rs738409 C>G, p.I148M) and HSD17B13 (rs72613567 T>TA; rs80182459, p.A192Lfs∗8) influences post-LT survival.

Methods

In this retrospective cohort study, data on 2346 adults who underwent first-time LT between January 1, 1999 and June 30, 2020 and who had donor DNA samples available at five large Transplant Immunology Laboratories in Texas, USA, were obtained from the United Network for Organ Sharing (UNOS). Duplicates, patients with insufficient donor DNA for genotyping, those who were <18 years of age at the time of transplant, had had a previous transplant or had missing genotype data were excluded. The primary outcomes were patient and graft survival after LT. The association between donor genotype and post-LT survival was examined using Kaplan-Meier method and multivariable-adjusted Cox proportional hazards models.

Findings

Median age of LT recipients was 57 [interquartile range (IQR), 50-62] years; 837 (35.7%) were women; 1362 (58.1%) White, 713 (30.4%) Hispanic, 182 (7.8%) Black/African-American. Median follow-up time was 3.95 years. Post-LT survival was not affected by donor PNPLA3 genotype but was significantly reduced among recipients of livers with two HSD17B13 loss-of-function (LoF) variants compared to those receiving livers with no HSD17B13 LoF alleles (unadjusted one-year survival: 82.6% vs 93.9%, P < 0.0001; five-year survival: 73.1% vs 82.9%, P = 0.0017; adjusted hazard ratio [HR], 2.25; 95% CI, 1.61-3.15 after adjustment for recipient age, sex, and self-reported ethnicity). Excess mortality was restricted to those receiving steroid induction immunosuppression (crude 90-day post-LT mortality, 9.3% [95% CI, 1.9%-16.1%] vs 1.9% [95% CI, 0.9%-2.9%] in recipients of livers with two vs no HSD17B13 LoF alleles, P = 0.0012; age, sex, and ethnicity-adjusted HR, 2.85; 95% CI, 1.72-4.71, P < 0.0001). No reduction was seen among patients who did not receive steroid induction (90-day mortality 3.1% [95% CI, 0%-7.3%] vs 2% [95% CI, 0.9%-3.1%], P = 0.65; adjusted HR, 1.17; 95% CI, 0.66-2.08, P = 0.60).

Interpretation

Donor HSD17B13 genotype adversely affects post-LT survival in patients receiving steroid induction. Additional studies are required to confirm this association.

Funding

The National Institutes of Health and American Society of Transplant Surgeons Collaborative Scientist Grant.

Associations of non-alcoholic fatty liver disease and cirrhosis with liver cancer in European and East Asian populations: A Mendelian randomization study

BACKGROUND

The positive relationships of non-alcoholic fatty liver disease (NAFLD) and cirrhosis with liver cancer were shown in previous observational studies, while further Mendelian randomization (MR) investigations are needed to confirm the possible causal associations.

AIMS

This study aimed to explore whether NAFLD and cirrhosis were causally related to liver cancer using MR in European and East Asian populations.

METHODS AND RESULTS

For European populations, NAFLD data were obtained from a genome-wide meta-analysis (8434 patients and 770 180 controls). The data on chronic elevation of alanine aminotransferase (cALT), a proxy of NAFLD, were derived from Million Veteran Program (68 725 patients and 95 472 controls). Cirrhosis data were collected from two sources: a genome-wide association study of five cohorts (4829 patients and 72 705 controls) and FinnGen (1931 patients and 216 861 controls). Liver cancer data were collected from FinnGen (304 patients and 174 006 controls). For East Asian populations, the data on cirrhosis (2184 patients and 210 269 controls) and hepatocellular carcinoma (1866 patients and 195 745 controls) were obtained from Biobank Japan. Three, 41, seven, six, and three single-nucleotide polymorphisms were used for NAFLD (European), cALT (European), cirrhosis (European-five cohorts), cirrhosis (European-FinnGen), and cirrhosis (East Asian), respectively. We used inverse-variance weighted as the primary method to calculate the odds ratio (OR) and 95% confidence interval (CI). Among European populations, genetically-predicted NAFLD, cALT, cirrhosis (five cohorts), and cirrhosis (FinnGen) were positively associated with liver cancer, with ORs (95% CIs) of 6.62 (3.81-11.50) (p < .001), 2.59 (1.70-3.94) (p < .001), 3.38 (2.41-4.75) (p < .001), and 2.62 (1.20-5.72) (p = .015). Among East Asian populations, there was also a positive association between genetically-predicted cirrhosis and hepatocellular carcinoma (OR = 2.12; 95% CI = 1.78-2.52; p < .001).

CONCLUSION

This study utilized MR to complementarily confirm the positive connections of NAFLD and cirrhosis with liver cancer, as identified in earlier observational research. Subsequent MR investigations involving more liver cancer cases are needed.

Germline Genetic Associations for Hepatobiliary Cancers

Hepatobiliary cancers (HBCs) include hepatocellular carcinoma, cholangiocarcinoma, and gallbladder carcinoma, which originate from the liver, bile ducts, and gallbladder, respectively. They are responsible for a substantial burden of cancer-related deaths worldwide. Despite knowledge of risk factors and advancements in therapeutics and surgical interventions, the prognosis for most patients with HBC remains bleak. There is evidence from familial aggregation and case-control studies to suggest a familial risk component in HBC susceptibility. Recent progress in genomics research has led to the identification of germline variants including single nucleotide polymorphisms (SNPs) and pathogenic or likely pathogenic (P/LP) variants in cancer-associated genes associated with HBC risk. These findings emerged from genome-wide association studies and next-generation sequencing techniques such as whole-exome sequencing. Patients with other cancer types, including breast, colon, ovarian, prostate, and pancreatic cancer, are recommended by guidelines to undergo germline genetic testing, but similar recommendations are lagging in HBC. This prompts the question of whether multi-gene panel testing should be integrated into clinical guidelines for HBC management. Here, we review the hereditary genetics of HBC, explore studies investigating SNPs and P/LP variants in HBC patients, discuss the clinical implications and potential for personalized treatments and impact on patient's family members, and conclude that additional studies are needed to examine how genetic testing can be applied clinically.

The intersection between alcohol-related liver disease and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) and alcohol-related liver disease (ALD) are the leading causes of chronic liver disease worldwide. NAFLD and ALD share pathophysiological, histological and genetic features and both alcohol and metabolic dysfunction coexist as aetiological factors in many patients with hepatic steatosis. A diagnosis of NAFLD requires the exclusion of significant alcohol consumption and other causes of liver disease. However, data suggest that significant alcohol consumption is often under-reported in patients classified as having NAFLD and that alcohol and metabolic factors interact to exacerbate the progression of liver disease. In this Review, we analyse existing data on the interaction between alcohol consumption and metabolic syndrome as well as the overlapping features and differences in the pathogenesis of ALD and NAFLD. We also discuss the clinical implications of the coexistence of alcohol consumption, of any degree, in patients with evidence of metabolic derangement as well as the use of alcohol biomarkers to detect alcohol intake. Finally, we summarize the evolving nomenclature of fatty liver disease and describe a recent proposal to classify patients at the intersection of NAFLD and ALD. We propose that, regardless of the presumed aetiology, patients with fatty liver disease should be evaluated for both metabolic syndrome and alcohol consumption to enable better prognostication and a personalized medicine approach.

Unraveling the pathogenesis of non-alcoholic fatty liver diseases through genome-wide association studies

Non-alcoholic fatty liver disease (NAFLD) is a significant health burden around the world, affecting approximately 25% of the population. Recent advances in human genetic databases have allowed for the identification of various single nucleotide polymorphisms associated with NAFLD-related traits. Investigating the functions of these genetic factors provides insight into the pathogenesis of NAFLD and potentially identifies novel therapeutic targets for NAFLD. In this review, we summarized current research on genes with NAFLD-associated mutations, highlighting phospholipid remodeling and spatially clustered loci as common pathological and genetic features of these mutations. These features suggest a complex yet intriguing mechanism of dissociated steatosis and insulin resistance, which is observed in a subset of patients and may lead to more precise therapy against NAFLD in the future.

The mitochondrial amidoxime reducing component-from prodrug-activation mechanism to drug-metabolizing enzyme and onward to drug target

The mitochondrial amidoxime-reducing component (mARC) is one of five known molybdenum enzymes in eukaryotes. mARC belongs to the MOSC domain superfamily, a large group of so far poorly studied molybdoenzymes. mARC was initially discovered as the enzyme activating N-hydroxylated prodrugs of basic amidines but has since been shown to also reduce a variety of other N-oxygenated compounds, for example, toxic nucleobase analogs. Under certain circumstances, mARC might also be involved in reductive nitric oxide synthesis through reduction of nitrite. Recently, mARC enzymes have received a lot of attention due to their apparent involvement in lipid metabolism and, in particular, because many genome-wide association studies have shown a common variant of human mARC1 to have a protective effect against liver disease. The mechanism linking mARC enzymes with lipid metabolism remains unknown. Here, we give a comprehensive overview of what is currently known about mARC enzymes, their substrates, structure, and apparent involvement in human disease.

Genetic variation and elevated liver enzymes during childhood, adolescence and early adulthood

BACKGROUND

Genetic factors influence the risk of fatty liver disease (FLD) in adults. The aim of this study was to test if, and when, genetic risk factors known to affect FLD in adults begin to exert their deleterious effects during childhood, adolescence and early adulthood.

METHODS

We included up to 4018 British children and adolescents from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Three genetic variants known to associate robustly with FLD in adults (PNPLA3 rs738409, TM6SF2 rs58542926 and HSD17B13 rs72613567) were tested for association with plasma levels of alanine transaminase (ALT) and aspartate transaminase (AST) during childhood (mean age: 9.9 years), early adolescence (15.5 years), late adolescence (17.8 years), and early adulthood (24.5 years). We also tested the associations of a 17-variant score and whole-genome polygenic risk scores (PRS) derived from associations in adults with plasma ALT and AST at the same four time points. Associations with elastography-derived liver steatosis and fibrosis were tested in early adulthood.

RESULTS

Genetic risk factors for FLD (individually, combined into a 3-variant score, a 17-variant score and as a genome-wide PRS), were associated with higher liver enzymes, beginning in childhood and throughout adolescence and early adulthood. The ALT-increasing effects of the genetic risk variants became larger with increasing age. The ALT-PRS was associated with liver steatosis in early adulthood. No genetic associations with fibrosis were observed.

CONCLUSIONS

Genetic factors that promote FLD in adults associate with elevated liver enzymes already during childhood, and their effects get amplified with increasing age.

Genome-wide association meta-analysis identifies 17 loci associated with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is common and partially heritable and has no effective treatments. We carried out a genome-wide association study (GWAS) meta-analysis of imaging (n = 66,814) and diagnostic code (3,584 cases versus 621,081 controls) measured NAFLD across diverse ancestries. We identified NAFLD-associated variants at torsin family 1 member B (TOR1B), fat mass and obesity associated (FTO), cordon-bleu WH2 repeat protein like 1 (COBLL1)/growth factor receptor-bound protein 14 (GRB14), insulin receptor (INSR), sterol regulatory element-binding transcription factor 1 (SREBF1) and patatin-like phospholipase domain-containing protein 2 (PNPLA2), as well as validated NAFLD-associated variants at patatin-like phospholipase domain-containing protein 3 (PNPLA3), transmembrane 6 superfamily 2 (TM6SF2), apolipoprotein E (APOE), glucokinase regulator (GCKR), tribbles homolog 1 (TRIB1), glycerol-3-phosphate acyltransferase (GPAM), mitochondrial amidoxime-reducing component 1 (MARC1), microsomal triglyceride transfer protein large subunit (MTTP), alcohol dehydrogenase 1B (ADH1B), transmembrane channel like 4 (TMC4)/membrane-bound O-acyltransferase domain containing 7 (MBOAT7) and receptor-type tyrosine-protein phosphatase δ (PTPRD). Implicated genes highlight mitochondrial, cholesterol and de novo lipogenesis as causally contributing to NAFLD predisposition. Phenome-wide association study (PheWAS) analyses suggest at least seven subtypes of NAFLD. Individuals in the top 10% and 1% of genetic risk have a 2.5-fold to 6-fold increased risk of NAFLD, cirrhosis and hepatocellular carcinoma. These genetic variants identify subtypes of NAFLD, improve estimates of disease risk and can guide the development of targeted therapeutics.

Genetic risk of fatty liver disease and mortality in the general population: A Mendelian randomization study

BACKGROUND & AIMS

Fatty liver disease has been associated with higher all-cause as well as liver-related, ischemic heart disease (IHD)-related and extrahepatic cancer-related mortality in observational epidemiological studies. We tested the hypothesis that fatty liver disease is a causal risk factor for higher mortality.

METHODS

We genotyped seven genetic variants known to be associated with fatty liver disease (in PNPLA3, TM6SF2, HSD17B13, MTARC1, MBOAT7, GCKR, and GPAM) in 110 913 individuals from the Danish general population. Hepatic steatosis was measured by hepatic computed tomography in n = 6965. Using a Mendelian randomization framework, we tested whether genetically proxied hepatic steatosis and/or elevated plasma alanine transaminase (ALT) was associated with liver-related mortality.

RESULTS

During a median follow-up of 9.5 years, 16 119 individuals died. In observational analyses, baseline elevated plasma ALT was associated with higher all-cause (1.26-fold), liver-related (9-fold), and extrahepatic cancer-related (1.25-fold) mortality. In genetic analyses, the risk alleles in PNPLA3, TM6SF2, and HSD17B13 were individually associated with higher liver-related mortality. The largest effects were seen for the PNPLA3 and TM6SF2 risk alleles, for which homozygous carriers had 3-fold and 6-fold, respectively, higher liver-related mortality than non-carriers. None of the risk alleles, individually or combined into risk scores, were robustly associated with all-cause, IHD-related, or extrahepatic cancer-related mortality. In instrumental variable analyses, genetically proxied hepatic steatosis and higher plasma ALT were associated with liver-related mortality.

CONCLUSIONS

Human genetic data support that fatty liver disease is a causal driver of liver-related mortality.

Advances in the genetics of nonalcoholic fatty liver disease

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of liver disease in the United States and has a strong heritable component. Advances in understanding the genetic underpinnings of NAFLD have revealed important insights into NAFLD pathogenesis, prognosis, and potential therapeutic targets. The purpose of this review is to summarize data on common and rare variants associated with NAFLD, combining risk variants into polygenic scores to predict NAFLD and cirrhosis as well as emerging evidence on using gene silencing as a novel therapeutic target in NAFLD.

RECENT FINDINGS

Protective variants in HSD17B13, MARC1 and CIDEB have been identified and a confer 10-50% lower risk of cirrhosis. Together, these as well as other NAFLD risk variants, including those in PNPLA3 and TM6SF2, can be combined to create polygenic risk scores associated with liver fat, cirrhosis, and hepatocellular carcinoma. Genomic analysis of extreme phenotypes including patients with lean NAFLD without visceral adiposity may uncover rare monogenic disorders with pathogenic and therapeutic implications and gene silencing strategies targeting HSD17B13 and PNPLA3 are being evaluated in early phase human studies as treatments for NAFLD.

SUMMARY

Advances in our understanding of the genetics of NAFLD will enable clinical risk stratification and yield potential therapeutic targets.

Longitudinal association between overweight years, polygenic risk and NAFLD, significant fibrosis and cirrhosis

BACKGROUND

Adiposity amplifies the genetic risk of non-alcoholic fatty liver disease (NAFLD).

AIM

We evaluated the association between overweight-years, a cumulative exposure based on the product of the duration and severity of excess body weight (body mass index (BMI) ≥ 25 kg/m2 ), and genetic risk on liver fat and fibrosis.

METHODS

This is a longitudinal analysis derived from a prospective cohort of adults in the Framingham Heart Study who underwent genotyping and vibration-controlled-transient-elastography with controlled attenuation parameter. Univariable and multivariable linear and logistic regression analyses were used to assess the association between overweight-years and liver fat and fibrosis. The association between genetic variants of liver fat (PNPLA3, TM6SF2, GCKR) and fibrosis (PNPLA3, TM6SF2, HSD17B13) was also assessed using a polygenic risk score.

RESULTS

Our sample included 2478 participants (54% women) with mean age and BMI of 40 (±8.5) years and 26.5(±5.1) kg/m2 , respectively. The mean follow-up was 14(±0.9) years, and each participant underwent three study visits. The prevalence of NAFLD was 28.3% (n = 700), and 207 (8.4%) had clinically significant fibrosis. In age-, sex- and diabetes-adjusted multivariable analyses, overweight-years (per SD) had a strong association with NAFLD (aOR 3.53 [95% CI: 3.10-4.02], p < 0.001), clinically significant fibrosis (aOR 1.60 [95% CI: 1.40-1.84], p < 0.001) and cirrhosis (aOR 1.81 [95% CI: 1.38-2.37], p < 0.001). High-polygenic risk was significantly associated with liver fat and clinically significant fibrosis (p < 0.05).

CONCLUSION

Overweight-years is strongly associated with NAFLD and clinically significant fibrosis and combined with polygenic risk may assist in defining the trajectory of NAFLD.

Hepatocyte mARC1 promotes fatty liver disease

Background & Aims

Non-alcoholic fatty liver disease (NAFLD) has a prevalence of ∼25% worldwide, with significant public health consequences yet few effective treatments. Human genetics can help elucidate novel biology and identify targets for new therapeutics. Genetic variants in mitochondrial amidoxime-reducing component 1 (MTARC1) have been associated with NAFLD and liver-related mortality; however, its pathophysiological role and the cell type(s) mediating these effects remain unclear. We aimed to investigate how MTARC1 exerts its effects on NAFLD by integrating human genetics with in vitro and in vivo studies of mARC1 knockdown.

Methods

Analyses including multi-trait colocalisation and Mendelian randomisation were used to assess the genetic associations of MTARC1. In addition, we established an in vitro long-term primary human hepatocyte model with metabolic readouts and used the Gubra Amylin NASH (GAN)-diet non-alcoholic steatohepatitis mouse model treated with hepatocyte-specific N-acetylgalactosamine (GalNAc)-siRNA to understand the in vivo impacts of MTARC1.

Results

We showed that genetic variants within the MTARC1 locus are associated with liver enzymes, liver fat, plasma lipids, and body composition, and these associations are attributable to the same causal variant (p.A165T, rs2642438 G>A), suggesting a shared mechanism. We demonstrated that increased MTARC1 mRNA had an adverse effect on these traits using Mendelian randomisation, implying therapeutic inhibition of mARC1 could be beneficial. In vitro mARC1 knockdown decreased lipid accumulation and increased triglyceride secretion, and in vivo GalNAc-siRNA-mediated knockdown of mARC1 lowered hepatic but increased plasma triglycerides. We found alterations in pathways regulating lipid metabolism and decreased secretion of 3-hydroxybutyrate upon mARC1 knockdown in vitro and in vivo.

Conclusions

Collectively, our findings from human genetics, and in vitro and in vivo hepatocyte-specific mARC1 knockdown support the potential efficacy of hepatocyte-specific targeting of mARC1 for treatment of NAFLD.

Impact and implications

We report that genetically predicted increases in MTARC1 mRNA associate with poor liver health. Furthermore, knockdown of mARC1 reduces hepatic steatosis in primary human hepatocytes and a murine NASH model. Together, these findings further underscore the therapeutic potential of targeting hepatocyte MTARC1 for NAFLD.

PNPLA3 Genotype and Diabetes Identify Patients With Nonalcoholic Fatty Liver Disease at High Risk of Incident Cirrhosis

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) can progress to cirrhosis and hepatic decompensation, but whether genetic variants influence the rate of progression to cirrhosis or are useful in risk stratification among patients with NAFLD is uncertain.

METHODS

We included participants from 2 independent cohorts, they Michigan Genomics Initiative (MGI) and UK Biobank (UKBB), who had NAFLD defined by elevated alanine aminotransferase (ALT) levels in the absence of alternative chronic liver disease. The primary predictors were genetic variants and metabolic comorbidities associated with cirrhosis. We conducted time-to-event analyses using Fine-Gray competing risk models.

RESULTS

We included 7893 and 46,880 participants from MGI and UKBB, respectively. In univariable analysis, PNPLA3-rs738409-GG genotype, diabetes, obesity, and ALT of ≥2× upper limit of normal were associated with higher incidence rate of cirrhosis in both MGI and UKBB. PNPLA3-rs738409-GG had additive effects with clinical risk factors including diabetes, obesity, and ALT elevations. Among patients with indeterminate fibrosis-4 (FIB4) scores (1.3-2.67), those with diabetes and PNPLA3-rs738409-GG genotype had an incidence rate of cirrhosis comparable to that of patients with high-risk FIB4 scores (>2.67) and 2.9-4.8 times that of patients with diabetes but CC/CG genotypes. In contrast, FIB4 <1.3 was associated with an incidence rate of cirrhosis significantly lower than that of FIB4 of >2.67, even in the presence of clinical risk factors and high-risk PNPLA3 genotype.

CONCLUSIONS

PNPLA3-rs738409 genotype and diabetes identified patients with NAFLD currently considered indeterminate risk (FIB4 1.3-2.67) who had a similar risk of cirrhosis as those considered high-risk (FIB4 >2.67). PNPLA3 genotyping may improve prognostication and allow for prioritization of intensive intervention.

Overweight/Obesity Increases the Risk of Overt Hepatic Encephalopathy after Transjugular Intrahepatic Portosystemic Shunt in Cirrhotic Patients

The purpose of this study was to investigate the effect of body mass index (BMI) on the prevalence of overt hepatic encephalopathy (OHE) after the transjugular intrahepatic portosystemic shunt (TIPS) procedure in decompensated cirrhotic patients. A retrospective observational cohort study of 145 cirrhotic patients receiving TIPS was carried out in our department from 2017 to 2020. The relationships between BMI and clinical outcomes including OHE, as well as risk factors of developing post-TIPS OHE, were analyzed. BMI was categorized as normal weight (18.5 ≤ BMI < 23.0 kg/m²), underweight (BMI < 18.5 kg/m²), and overweight/obese (BMI ≥ 23.0 kg/m²). Among the 145 patients, 52 (35.9%) were overweight/obese and 50 (34%) had post-TIPS OHE. Overweight/obese patients more frequently had OHE compared with normal weight patients (OR: 2.754, 95% CI: 1.236-6.140; p = 0.013). Overweight/obesity (p = 0.013) and older age (p = 0.030) were independent risk factors for post-TIPS OHE according to the logistic regression analysis. Kaplan-Meier curve analysis suggested that overweight/obese patients had the highest cumulative incidence of OHE (log-rank p = 0.0118). In conclusion, overweight/obesity and older age may raise the risk of post-TIPS OHE in cirrhotic patients.

Admixture Mapping in African Americans Identifies New Risk Loci for HCV-Related Cirrhosis

BACKGROUND & AIMS

Cirrhosis is the main predisposing condition for hepatocellular carcinoma. Host genetic risk factors have been reported for cirrhosis; however, whether there is a genetic contribution to racial disparities in cirrhosis requires further investigation.

METHODS

We used an affected-only mapping by admixture linkage disequilibrium analysis to characterize the genetic risk of cirrhosis in 227 African American patients with cirrhosis genotyped at 19,804 ancestry-informative marker single nucleotide polymorphisms. We additionally performed analyses stratified by hepatitis C virus (HCV) infection status. To replicate our findings, we conducted a case-control analysis in an external study population (452 cases and 196 controls).

RESULTS

The mean age of patients was 63.3 years and 98.2% were male. Risk factors for cirrhosis included HCV infection (83.7%) and alcohol abuse (56.4%). In the admixture mapping analysis, we found that European ancestry on chromosome 2q21.1 and African ancestry on chromosome 6p21.2 were associated with increased risk of cirrhosis in African Americans. In the fine-mapping analysis, we identified regions near POTEKP on 2q21.1 (P = .0001) and DNAH8 on 6p21.2 (P = .0017) that were associated with cirrhosis. As the admixture peaks in the HCV-positive patients were the same as those in the overall group, findings in the analysis are reflective of the HCV-positive group. In the replication analysis, the results on chromosome 2 were not significant after adjusting for multiple comparisons, and we could not replicate the results on chromosome 6.

CONCLUSIONS

We used admixture mapping to identify novel genomic regions on 2q21.1 and 6p21.2 that may be associated with HCV-related cirrhosis risk in African Americans.

Genomic analyses of hair from Ludwig van Beethoven

Ludwig van Beethoven (1770-1827) remains among the most influential and popular classical music composers. Health problems significantly impacted his career as a composer and pianist, including progressive hearing loss, recurring gastrointestinal complaints, and liver disease. In 1802, Beethoven requested that following his death, his disease be described and made public. Medical biographers have since proposed numerous hypotheses, including many substantially heritable conditions. Here we attempt a genomic analysis of Beethoven in order to elucidate potential underlying genetic and infectious causes of his illnesses. We incorporated improvements in ancient DNA methods into existing protocols for ancient hair samples, enabling the sequencing of high-coverage genomes from small quantities of historical hair. We analyzed eight independently sourced locks of hair attributed to Beethoven, five of which originated from a single European male. We deemed these matching samples to be almost certainly authentic and sequenced Beethoven's genome to 24-fold genomic coverage. Although we could not identify a genetic explanation for Beethoven's hearing disorder or gastrointestinal problems, we found that Beethoven had a genetic predisposition for liver disease. Metagenomic analyses revealed furthermore that Beethoven had a hepatitis B infection during at least the months prior to his death. Together with the genetic predisposition and his broadly accepted alcohol consumption, these present plausible explanations for Beethoven's severe liver disease, which culminated in his death. Unexpectedly, an analysis of Y chromosomes sequenced from five living members of the Van Beethoven patrilineage revealed the occurrence of an extra-pair paternity event in Ludwig van Beethoven's patrilineal ancestry.

Abdominal obesity and alcohol use modify the impact of genetic risk for incident advanced liver disease in the general population

BACKGROUND & AIMS

Genetic variants, abdominal obesity and alcohol use are risk factors for incident liver disease (ILD). We aimed to study whether variants either alone or when aggregated into genetic risk scores (GRSs) associate with ILD, and whether waist-hip ratio (WHR) or alcohol use interacts with this risk.

METHODS

Our study included 33 770 persons (mean age 50 years, 47% men) who participated in health-examination surveys (FINRISK 1992-2012 or Health 2000) with data on alcohol use, WHR and 63 genotypes associated with liver disease. Data were linked with national health registers for liver-related outcomes (hospitalizations, malignancies and death). Exclusions were baseline clinical liver disease. Mean follow-up time was 12.2 years. Cox regression analyses between variants and ILD were adjusted for age, sex and BMI.

RESULTS

Variants in PNPLA3, IFNL4, TM6SF2, FDFT1, PPP1R3B, SERPINA1 and HSD17B13 were associated with ILD. GRSs calculated from these variants were not associated with WHR or alcohol use, but were exponentially associated with ILD (up to 25-fold higher risk in high versus low score). The risk of ILD in individuals with high GRS and high WHR or alcohol use compared with those with none of these risk factors was increased by up to 90-fold. GRSs provided new prognostic information particularly in individuals with high WHR.

CONCLUSIONS

The effect of multiple genetic variants on the risk of ILD is potentiated by abdominal obesity and alcohol use. Simple GRSs may help to identify individuals with adverse lifestyle who are at a particularly high risk of ILD.

Multitrait genome-wide analyses identify new susceptibility loci and candidate drugs to primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a rare autoimmune bile duct disease that is strongly associated with immune-mediated disorders. In this study, we implemented multitrait joint analyses to genome-wide association summary statistics of PSC and numerous clinical and epidemiological traits to estimate the genetic contribution of each trait and genetic correlations between traits and to identify new lead PSC risk-associated loci. We identified seven new loci that have not been previously reported and one new independent lead variant in the previously reported locus. Functional annotation and fine-mapping nominated several potential susceptibility genes such as MANBA and IRF5. Network-based in silico drug efficacy screening provided candidate agents for further study of pharmacological effect in PSC.

Metabolic Hijacking of Hexose Metabolism to Ascorbate Synthesis Is the Unifying Biochemical Basis of Murine Liver Fibrosis

We wished to understand the metabolic reprogramming underlying liver fibrosis progression in mice. Administration to male C57BL/6J mice of the hepatotoxins carbon tetrachloride (CCl4), thioacetamide (TAA), or a 60% high-fat diet, choline-deficient, amino-acid-defined diet (HF-CDAA) was conducted using standard protocols. Livers collected at different times were analyzed by gas chromatography-mass spectrometry-based metabolomics. RNA was extracted from liver and assayed by qRT-PCR for mRNA expression of 11 genes potentially involved in the synthesis of ascorbic acid from hexoses, Gck, Adpgk, Hk1, Hk2, Ugp2, Ugdh, Ugt1a1, Akr1a4, Akr1b3, Rgn and Gulo. All hepatotoxins resulted in similar metabolic changes during active fibrogenesis, despite different etiology and resultant scarring pattern. Diminished hepatic glucose, galactose, fructose, pentose phosphate pathway intermediates, glucuronic acid and long-chain fatty acids were compensated by elevated ascorbate and the product of collagen prolyl 4-hydroxylase, succinate and its downstream metabolites fumarate and malate. Recovery from the HF-CDAA diet challenge (F2 stage fibrosis) after switching to normal chow was accompanied by increased glucose, galactose, fructose, ribulose 5-phosphate, glucuronic acid, the ascorbate metabolite threonate and diminished ascorbate. During the administration of CCl4, TAA and HF-CDAA, aldose reductase Akr1b3 transcription was induced six- to eightfold, indicating increased conversion of glucuronic acid to gulonic acid, a precursor of ascorbate synthesis. Triggering hepatic fibrosis by three independent mechanisms led to the hijacking of glucose and galactose metabolism towards ascorbate synthesis, to satisfy the increased demand for ascorbate as a cofactor for prolyl 4-hydroxylase for mature collagen production. This metabolic reprogramming and causal gene expression changes were reversible. The increased flux in this pathway was mediated predominantly by increased transcription of aldose reductase Akr1b3.

Current Challenges and Future Direction in Surveillance for Hepatocellular Carcinoma in Patients with Nonalcoholic Fatty Liver Disease

The burden for hepatocellular carcinoma (HCC) attributed to nonalcoholic fatty liver disease (NAFLD) continues to grow in parallel with rising global trends in obesity. The risk of HCC is elevated among patients with NAFLD-related cirrhosis to a level that justifies surveillance based on cost-effectiveness argument. The quality of current evidence for HCC surveillance in all patients with chronic liver disease is poor, and even lower in those with NAFLD. For a lack of more precise risk-stratification tools, current approaches to defining a target population in noncirrhotic NAFLD are limited to noninvasive tests for liver fibrosis, as a proxy for liver-related morbidity and mortality. Beyond etiology and severity of liver disease, traditional and metabolic risk factors, such as diabetes mellitus, older age, male gender and tobacco smoking, are not enough for HCC risk stratification for surveillance efficacy and effectiveness in NAFLD. There is an association between molecular and genetic factors and HCC risk in NAFLD, and risk models integrating both clinical and genetic factors will be key to personalizing HCC risk. In this review, we discuss concerns regarding defining a target population, surveillance test accuracy, surveillance underuse, and other cost-effective considerations for HCC surveillance in individuals with NAFLD.

Alcohol consumption and metabolic syndrome: Clinical and epidemiological impact on liver disease

Alcohol use and metabolic syndrome are highly prevalent in the population and frequently co-exist. Both are implicated in a large range of health problems, including chronic liver disease, hepatocellular carcinoma, and liver-related outcomes (i.e. decompensation or liver transplantation). Studies have yielded mixed results regarding the effects of mild-moderate alcohol consumption on the risk of metabolic syndrome and fatty liver disease, possibly due to methodological differences. The few available prospective studies have indicated that mild-moderate alcohol use is associated with an increase in liver-related outcomes. This conclusion was substantiated by systems biology analyses suggesting that alcohol and metabolic syndrome may play a similar role in fatty liver disease, potentiating an already existing dysregulation of common vital homeostatic pathways. Alcohol and metabolic factors are independently and jointly associated with liver-related outcomes. Indeed, metabolic syndrome increases the risk of liver-related outcomes, regardless of alcohol intake. Moreover, the components of metabolic syndrome appear to have additive effects when it comes to the risk of liver-related outcomes. A number of population studies have implied that measures of central/abdominal obesity, such as the waist-to-hip ratio, can predict liver-related outcomes more accurately than BMI, including in individuals who consume harmful quantities of alcohol. Many studies even point to synergistic interactions between harmful alcohol use and many metabolic components. This accumulating evidence showing independent, combined, and modifying effects of alcohol and metabolic factors on the onset and progression of chronic liver disease highlights the multifactorial background of liver disease in the population. The available evidence suggests that more holistic approaches could be useful for risk prediction, diagnostics and treatment planning.

Diet and Risk of Non-Alcoholic Fatty Liver Disease, Cirrhosis, and Liver Cancer: A Large Prospective Cohort Study in UK Biobank

Background and Aims: Epidemiological evidence has shown the association between nutritional habits and liver disease. However, results remain conflicting. This study investigated the influence of dietary factors on the risk of incident non-alcoholic fatty liver disease (NAFLD), cirrhosis, and liver cancer. Methods: Data from the UK Biobank database were analyzed (n = 372,492). According to baseline data from the food frequency questionnaire, two main dietary patterns (Western and prudent) were identified using principal component analysis. We used cox proportional hazards models to explore the associations of individual food groups and dietary patterns with NAFLD, cirrhosis, and liver cancer. Results: During a median follow-up of 12 years, 3527 hospitalized NAFLD, 1643 cirrhosis, and 669 liver cancer cases were recorded among 372,492 participants without prior history of cancer or chronic liver diseases at baseline. In multivariable adjusted analysis, participants in the high tertile of Western dietary pattern score had an 18% (95%CI = 1.09−1.29), 21% (95%CI = 1.07−1.37), and 24% (95%CI = 1.02−1.50) higher risk of incident NAFLD, liver cirrhosis, and liver cancer, respectively, compared with the low tertile. Participants in the high tertile of prudent scores had a 15% (95%CI = 0.75−0.96) lower risk of cirrhosis, as compared with those in the low tertile. In addition, the higher consumption of red meat and the lower consumption of fruit, cereal, tea, and dietary fiber were significantly associated with a higher risk of NAFLD, cirrhosis, and liver cancer (ptrend < 0.05). Conclusions: This large prospective cohort study showed that an increased intake of food from the Western dietary pattern could be correlated with an increased risk of chronic liver diseases, while the prudent pattern was only correlated with a reduced liver cirrhosis risk. These data may provide new insights into lifestyle interventions for the prevention of chronical liver diseases.

Risk of nonalcoholic fatty liver disease and associations with gastrointestinal cancers

Metabolic syndrome may contribute to the rising incidence of multiple gastrointestinal (GI) cancers in recent birth cohorts. However, other than hepatocellular carcinoma, the association between nonalcoholic fatty liver disease (NAFLD) and risk of non-liver GI cancers is unexplored. We prospectively examined the associations of NAFLD risk with GI cancers among 319,290 participants in the UK Biobank (2006-2019). Baseline risk for NAFLD was estimated using the Dallas Steatosis Index, a validated prediction tool. Multivariable Cox models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) according to NAFLD risk categories: low (<20%), intermediate (20%-49%), and high (≥50%). We also examined the associations by age of cancer diagnosis (earlier onset [<60] vs. ≥60). A total of 273 incident liver cancer and 4789 non-liver GI cancer cases were diagnosed. Compared with individuals at low risk for NAFLD, those at high risk had 2.41-fold risk of liver cancer (RR = 2.41, 95% CI: 1.73-3.35) and 23% increased risk of non-liver GI cancers (RR = 1.23, 95% CI: 1.14-1.32) (all ptrend  < 0.001). Stronger associations were observed for men and individuals who were obese (all pinteraction  < 0.05). NAFLD-associated elevated risk was stronger for earlier-onset cancers. For each 25% increase in NAFLD risk, the RRs for earlier-onset cancers were 1.32 (95% CI: 1.05-1.66) for esophageal cancer, 1.35 (95% CI: 1.06-1.72) for gastric cancer, 1.34 (95% CI: 1.09-1.65) for pancreatic cancer, and 1.10 (95% CI: 1.01-1.20) for colorectal cancer. Conclusion: NAFLD risk was associated with an increased risk of liver and most GI cancers, especially those of earlier onset.

Genetic modifiers of penetrance to liver endpoints in HFE hemochromatosis: Associations in a large community cohort

BACKGROUND

The iron overload condition hereditary hemochromatosis (HH) can cause liver cirrhosis and cancer, diabetes, and arthritis. Males homozygous for the p.C282Y missense mutation in the Homeostatin Iron Regulator (HFE) gene have greatest risk; yet, only a minority develop these conditions. We aimed to determine whether common genetic variants influencing iron levels or liver disease risk in the general population also modify clinical penetrance in HFE p.C282Y and p.H63D carriers.

METHODS

We studied 1294 male and 1596 female UK Biobank HFE p.C282Y homozygous participants of European ancestry with medical records up to 14 years after baseline assessment. Polygenic scores quantified genetic effects of blood iron biomarkers and relevant diseases (identified in the general population). Analyses were also performed in other HFE p.C282Y/p.H63D genotype groups.

RESULTS

In male p.C282Y homozygotes, a higher iron polygenic score increased the risk of liver fibrosis or cirrhosis diagnoses (odds ratio for the top 20% of iron polygenic score vs. the bottom 20% = 4.90: 95% confidence intervals, 1.63-14.73; p = 0.005), liver cancer, and osteoarthritis but not diabetes. A liver cirrhosis polygenic score was associated with liver cancer diagnoses. In female p.C282Y homozygotes, the osteoarthritis polygenic score was associated with increased osteoarthritis diagnoses and type-2 diabetes polygenic score with diabetes. However, the iron polygenic score was not robustly associated with diagnoses in p.C282Y female homozygotes or in other p.C282Y/p.H63D genotypes.

CONCLUSIONS

HFE p.C282Y homozygote penetrance to clinical disease in a large community cohort was partly explained by common genetic variants that influence iron and risks of related diagnoses in the general population, including polygenic scores in HH screening and diagnosis, may help in estimating prognosis and treatment planning.

Multiomics study of nonalcoholic fatty liver disease

Nonalcoholic fatty liver (NAFL) and its sequelae are growing health problems. We performed a genome-wide association study of NAFL, cirrhosis and hepatocellular carcinoma, and integrated the findings with expression and proteomic data. For NAFL, we utilized 9,491 clinical cases and proton density fat fraction extracted from 36,116 liver magnetic resonance images. We identified 18 sequence variants associated with NAFL and 4 with cirrhosis, and found rare, protective, predicted loss-of-function variants in MTARC1 and GPAM, underscoring them as potential drug targets. We leveraged messenger RNA expression, splicing and predicted coding effects to identify 16 putative causal genes, of which many are implicated in lipid metabolism. We analyzed levels of 4,907 plasma proteins in 35,559 Icelanders and 1,459 proteins in 47,151 UK Biobank participants, identifying multiple proteins involved in disease pathogenesis. We show that proteomics can discriminate between NAFL and cirrhosis. The present study provides insights into the development of noninvasive evaluation of NAFL and new therapeutic options.

Synergistic Associations of PNPLA3 I148M Variant, Alcohol Intake, and Obesity With Risk of Cirrhosis, Hepatocellular Carcinoma, and Mortality

IMPORTANCE

Alcohol drinking and obesity are associated with an increased risk of cirrhosis and hepatocellular carcinoma (HCC), but the risk is not uniform among people with these risk factors. Genetic variants, such as I148M in the patatin-like phospholipase domain-containing protein 3 (PNPLA3) gene, may play an important role in modulating cirrhosis and HCC risk.

OBJECTIVE

To investigate the joint associations of the PNPLA3 I148M variant, alcohol intake, and obesity with the risk of cirrhosis, HCC, and liver disease-related mortality.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study analyzed 414 209 participants enrolled in the UK Biobank study from March 2006 to December 2010. Participants had no previous diagnosis of cirrhosis and HCC and were followed up through March 2021.

EXPOSURES

Self-reported alcohol intake (nonexcessive vs excessive), obesity (body mass index ≥30 [calculated as weight in kilograms divided by height in meters squared]), and PNPLA3 I148M variant status (noncarrier, heterozygous carrier, or homozygous carrier) from initial assessment.

MAIN OUTCOMES AND MEASURES

The primary outcomes were incident cirrhosis and HCC cases and liver disease-related death ascertained from inpatient hospitalization records and death registry. The risks were calculated by Cox proportional hazards regression models.

RESULTS

A total of 414 209 participants (mean [SD] age, 56.3 [8.09] years; 218 567 women [52.8%]; 389 452 White race and ethnicity [94.0%]) were included. Of these participants, 2398 participants (0.6%) developed cirrhosis (5.07 [95% CI, 4.87-5.28] cases per 100 person-years), 323 (0.1%) developed HCC (0.68 [95% CI, 0.61-0.76] cases per 100 person-years), and 878 (0.2%) died from a liver disease-related cause (1.76 [95% CI, 1.64-1.88] cases per 100 person-years) during a median follow-up of 10.9 years. Synergistic interactions between the PNPLA3 I148M variant, obesity, and alcohol intake were associated with the risk of cirrhosis, HCC, and liver disease-related mortality. The risk of cirrhosis increased supramultiplicatively (adjusted hazard ratio [aHR], 17.52; 95% CI, 12.84-23.90) in individuals with obesity, with excessive drinking, and who were homozygous carriers compared with those with no obesity, with nonexcessive drinking, and who were noncarriers. Supramultiplicative associations between the 3 factors and risks of HCC were found in individuals with 3 risk factors (aHR, 30.13; 95% CI, 16.51-54.98) and liver disease-related mortality (aHR, 21.82; 95% CI, 13.78-34.56). The PNPLA3 I148M variant status significantly differentiated the risk of cirrhosis, HCC, and liver disease-related mortality in persons with excessive drinking and obesity.

CONCLUSIONS AND RELEVANCE

This study found synergistic associations of the PNPLA3 I148M variant, excessive alcohol intake, and obesity with increased risk of cirrhosis, HCC, and liver disease-related death in the general population. The PNPLA3 I148M variant status may help refine the risk stratification for liver disease in persons with excessive drinking and obesity who may need early preventive measures.

Applications of human organoids in the personalized treatment for digestive diseases

Digestive system diseases arise primarily through the interplay of genetic and environmental influences; there is an urgent need in elucidating the pathogenic mechanisms of these diseases and deploy personalized treatments. Traditional and long-established model systems rarely reproduce either tissue complexity or human physiology faithfully; these shortcomings underscore the need for better models. Organoids represent a promising research model, helping us gain a more profound understanding of the digestive organs; this model can also be used to provide patients with precise and individualized treatment and to build rapid in vitro test models for drug screening or gene/cell therapy, linking basic research with clinical treatment. Over the past few decades, the use of organoids has led to an advanced understanding of the composition of each digestive organ and has facilitated disease modeling, chemotherapy dose prediction, CRISPR-Cas9 genetic intervention, high-throughput drug screening, and identification of SARS-CoV-2 targets, pathogenic infection. However, the existing organoids of the digestive system mainly include the epithelial system. In order to reveal the pathogenic mechanism of digestive diseases, it is necessary to establish a completer and more physiological organoid model. Combining organoids and advanced techniques to test individualized treatments of different formulations is a promising approach that requires further exploration. This review highlights the advancements in the field of organoid technology from the perspectives of disease modeling and personalized therapy.

Multiancestry exome sequencing reveals INHBE mutations associated with favorable fat distribution and protection from diabetes

Body fat distribution is a major, heritable risk factor for cardiometabolic disease, independent of overall adiposity. Using exome-sequencing in 618,375 individuals (including 160,058 non-Europeans) from the UK, Sweden and Mexico, we identify 16 genes associated with fat distribution at exome-wide significance. We show 6-fold larger effect for fat-distribution associated rare coding variants compared with fine-mapped common alleles, enrichment for genes expressed in adipose tissue and causal genes for partial lipodystrophies, and evidence of sex-dimorphism. We describe an association with favorable fat distribution (p = 1.8 × 10^-09), favorable metabolic profile and protection from type 2 diabetes (~28% lower odds; p = 0.004) for heterozygous protein-truncating mutations in INHBE, which encodes a circulating growth factor of the activin family, highly and specifically expressed in hepatocytes. Our results suggest that inhibin βE is a liver-expressed negative regulator of adipose storage whose blockade may be beneficial in fat distribution-associated metabolic disease.

A minority of somatically mutated genes in pre-existing fatty liver disease have prognostic importance in the development of NAFLD

BACKGROUND

Understanding the genetics of liver disease has the potential to facilitate clinical risk stratification. We recently identified acquired somatic mutations in six genes and one lncRNA in pre-existing fatty liver disease. We hypothesised that germline variation in these genes might be associated with the risk of developing steatosis and contribute to the prediction of disease severity.

METHODS

Genome-wide association study (GWAS) summary statistics were extracted from seven studies (>1.7 million participants) for variants near ACVR2A, ALB, CIDEB, FOXO1, GPAM, NEAT1 and TNRC6B for: aminotransferases, liver fat, HbA1c, diagnosis of NAFLD, ARLD and cirrhosis. Findings were replicated using GWAS data from multiple independent cohorts. A phenome-wide association study was performed to examine for related metabolic traits, using both common and rare variants, including gene-burden testing.

RESULTS

There was no evidence of association between rare germline variants or SNPs near five genes (ACVR2A, ALB, CIDEB, FOXO1 and TNRC6B) and risk or severity of liver disease. Variants in GPAM (proxies for p.Ile43Val) were associated with liver fat (p = 3.6 × 10-13 ), ALT (p = 2.8 × 10-39 ) and serum lipid concentrations. Variants in NEAT1 demonstrated borderline significant associations with ALT (p = 1.9 × 10-11 ) and HbA1c, but not with liver fat, as well as influencing waist-to-hip ratio, adjusted for BMI.

CONCLUSIONS

Despite the acquisition of somatic mutations at these loci during progressive fatty liver disease, we did not find associations between germline variation and markers of liver disease, except in GPAM. In the future, larger sample sizes may identify associations. Currently, germline polygenic risk scores will not capture data from genes affected by somatic mutations.

Variance-quantitative trait loci enable systematic discovery of gene-environment interactions for cardiometabolic serum biomarkers

Gene-environment interactions represent the modification of genetic effects by environmental exposures and are critical for understanding disease and informing personalized medicine. These often induce differential phenotypic variance across genotypes; these variance-quantitative trait loci can be prioritized in a two-stage interaction detection strategy to greatly reduce the computational and statistical burden and enable testing of a broader range of exposures. We perform genome-wide variance-quantitative trait locus analysis for 20 serum cardiometabolic biomarkers by multi-ancestry meta-analysis of 350,016 unrelated participants in the UK Biobank, identifying 182 independent locus-biomarker pairs (p < 4.5×10-9). Most are concentrated in a small subset (4%) of loci with genome-wide significant main effects, and 44% replicate (p < 0.05) in the Women's Genome Health Study (N = 23,294). Next, we test each locus-biomarker pair for interaction across 2380 exposures, identifying 847 significant interactions (p < 2.4×10-7), of which 132 are independent (p < 0.05) after accounting for correlation between exposures. Specific examples demonstrate interaction of triglyceride-associated variants with distinct body mass- versus body fat-related exposures as well as genotype-specific associations between alcohol consumption and liver stress at the ADH1B gene. Our catalog of variance-quantitative trait loci and gene-environment interactions is publicly available in an online portal.

Interactions of physical activity, muscular fitness, adiposity, and genetic risk for NAFLD

Genetic predisposition and unhealthy lifestyle are risk factors for nonalcoholic fatty liver disease (NAFLD). We investigated whether the genetic risk of NAFLD is modified by physical activity, muscular fitness, and/or adiposity. In up to 242,524 UK Biobank participants without excessive alcohol intake or known liver disease, we examined cross-sectional interactions and joint associations of physical activity, muscular fitness, body mass index (BMI), and a genetic risk score (GRS) with alanine aminotransferase (ALT) levels and the proxy definition for suspected NAFLD of ALT levels > 30 U/L in women and >40 U/L in men. Genetic predisposition to NAFLD was quantified using a GRS consisting of 68 loci known to be associated with chronically elevated ALT. Physical activity was assessed using accelerometry, and muscular fitness was estimated by measuring handgrip strength. We found that increased physical activity and grip strength modestly attenuate genetic predisposition to elevation in ALT levels, whereas higher BMI markedly amplifies it (all p values < 0.001). Among those with normal weight and high level of physical activity, the odds of suspected NAFLD were 1.6-fold higher in those with high versus low genetic risk (reference group). In those with high genetic risk, the odds of suspected NAFLD were 12-fold higher in obese participants with low physical activity versus those with normal weight and high physical activity (odds ratio for NAFLD = 19.2 and 1.6, respectively, vs. reference group). Conclusion: In individuals with high genetic predisposition for NAFLD, maintaining a normal body weight and increased physical activity may reduce the risk of NAFLD.

Inherited basis of visceral, abdominal subcutaneous and gluteofemoral fat depots

For any given level of overall adiposity, individuals vary considerably in fat distribution. The inherited basis of fat distribution in the general population is not fully understood. Here, we study up to 38,965 UK Biobank participants with MRI-derived visceral (VAT), abdominal subcutaneous (ASAT), and gluteofemoral (GFAT) adipose tissue volumes. Because these fat depot volumes are highly correlated with BMI, we additionally study six local adiposity traits: VAT adjusted for BMI and height (VATadj), ASATadj, GFATadj, VAT/ASAT, VAT/GFAT, and ASAT/GFAT. We identify 250 independent common variants (39 newly-identified) associated with at least one trait, with many associations more pronounced in female participants. Rare variant association studies extend prior evidence for PDE3B as an important modulator of fat distribution. Local adiposity traits (1) highlight depot-specific genetic architecture and (2) enable construction of depot-specific polygenic scores that have divergent associations with type 2 diabetes and coronary artery disease. These results - using MRI-derived, BMI-independent measures of local adiposity - confirm fat distribution as a highly heritable trait with important implications for cardiometabolic health outcomes.

A rare genetic variant in the manganese transporter SLC30A10 and elevated liver enzymes in the general population

BACKGROUND

A genetic variant in the manganese transporter SLC30A10 (rs188273166, p.Thr95Ile) was associated with increased plasma alanine transaminase (ALT) in a recent genome-wide association study in the UK Biobank (UKB). The aims of the present study were to test the association of rs188273166 with ALT in an independent cohort, and to begin to assess the clinical, hepatic, and biochemical phenotypes associated with the variant.

METHODS

We included n = 334,886 white participants from UKB, including 14,462 with hepatic magnetic resonance imaging (MRI), and n = 113,612 individuals from the Copenhagen City Heart Study and the Copenhagen General Population Study combined.

RESULTS

Genotyping SLC30A10 p.Thr95Ile identified 816 heterozygotes in the UKB and 111 heterozygotes in the Copenhagen cohort. Compared to noncarriers, heterozygotes had 4 and 5 U/L higher levels of ALT in the UKB and Copenhagen cohort, respectively, and 3 U/L higher plasma aspartate transaminase and gamma-glutamyl transferase in the UKB. Heterozygotes also had higher corrected T1 on liver MRI, a marker of hepatic inflammation (p = 4 × 10-7), but no change in MRI-quantified steatosis (p = 0.57). Plasma manganese was within the normal range in nine heterozygotes that provided new blood samples. SLC30A10 p.Thr95Ile heterozygotes had an eightfold increased risk of biliary tract cancer in UKB (p = 4 × 10-7), but this association was not replicated in the Copenhagen cohort.

CONCLUSIONS

SLC30A10 p.Thr95Ile was associated with elevated liver enzymes in two large general population cohorts, and with MRI-quantified hepatic inflammation. A rare genetic variant (p.Thr95Ile) in the manganese transporter SLC30A10 is associated with elevated plasma alanine transaminase (ALT) and higher corrected T1 on liver MRI, markers of liver inflammation. These data support that the variant may increase the risk of liver disease.

Identifying and Exploring the Candidate Susceptibility Genes of Cirrhosis Using the Multi-Tissue Transcriptome-Wide Association Study

Objective: We identify and explore the candidate susceptibility genes for cirrhosis and their underlying biological mechanism.

Methods: We downloaded the genome-wide association studies summary data of 901 cirrhosis cases and 451,363 controls and integrated them with reference models of five potential tissues from the Genotype-Tissue Expression (GTEx) Project, including whole blood, liver, pancreas, spleen, and thyroid, to identify genes whose expression is predicted to be associated with cirrhosis. Then, we downloaded gene expression data of individuals with hepatocellular carcinoma from TCGA database to conduct differential expression analysis to validate these identified genes and explored their possible role in driving cirrhosis via functional enrichment and gene set enrichment analysis (GSEA).

Results: We identified 10 significant genes (SKIV2L, JPH4, UQCC2, RP11-91I8.3, MAU2, ERAP1, PUS3, ZNF677, ARHGAP40, and SHANK3) associated with cirrhosis at a Bonferroni-corrected threshold of p < 0.01, among which two (SKIV2L and JPH4) were identified in the liver and five (SKIV2L, JPH4, MAU2, SHANK3, and UQCC2) were validated by differential expression analysis at an FDR-corrected threshold of p < 0.01. The enrichment analysis showed that the degradation process of RNA, which is enriched by 58 genes, is significantly under-enriched in liver cancer tissues (p = 0.0268).

Conclusion: We have identified several candidate genes for cirrhosis in multiple tissues and performed differential genetic analysis using the liver cancer database to verify the significant genes. We found that the genes SKIV2L and JPH4 identified in the liver are of particular concern. Finally, through enrichment analysis, we speculate that the process of mRNA transcription and RNA degradation may play a role in cirrhosis.

The rs429358 Locus in Apolipoprotein E Is Associated With Hepatocellular Carcinoma in Patients With Cirrhosis

The host genetic background for hepatocellular carcinoma (HCC) is incompletely understood. We aimed to determine if four germline genetic polymorphisms, rs429358 in apolipoprotein E (APOE), rs2642438 in mitochondrial amidoxime reducing component 1 (MARC1), rs2792751 in glycerol-3-phosphate acyltransferase (GPAM), and rs187429064 in transmembrane 6 superfamily member 2 (TM6SF2), previously associated with progressive alcohol-related and nonalcoholic fatty liver disease, are also associated with HCC. Four HCC case-control data sets were constructed, including two mixed etiology data sets (UK Biobank and FinnGen); one hepatitis C virus (HCV) cohort (STOP-HCV), and one alcohol-related HCC cohort (Dresden HCC). The frequency of each variant was compared between HCC cases and cirrhosis controls (i.e., patients with cirrhosis without HCC). Population controls were also considered. Odds ratios (ORs) associations were calculated using logistic regression, adjusting for age, sex, and principal components of genetic ancestry. Fixed-effect meta-analysis was used to determine the pooled effect size across all data sets. Across four case-control data sets, 2,070 HCC cases, 4,121 cirrhosis controls, and 525,779 population controls were included. The rs429358:C allele (APOE) was significantly less frequent in HCC cases versus cirrhosis controls (OR, 0.71; 95% confidence interval [CI], 0.61-0.84; P = 2.9 × 10-5 ). Rs187429064:G (TM6SF2) was significantly more common in HCC cases versus cirrhosis controls and exhibited the strongest effect size (OR, 2.03; 95% CI, 1.45-2.86; P = 3.1 × 10-6 ). In contrast, rs2792751:T (GPAM) was not associated with HCC (OR, 1.01; 95% CI, 0.90-1.13; P = 0.89), whereas rs2642438:A (MARC1) narrowly missed statistical significance (OR, 0.91; 95% CI, 0.84-1.00; P = 0.043). Conclusion: This study associates carriage of rs429358:C (APOE) with a reduced risk of HCC in patients with cirrhosis. Conversely, carriage of rs187429064:G in TM6SF2 is associated with an increased risk of HCC in patients with cirrhosis.

A genome-wide meta-analysis identifies 50 genetic loci associated with carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and has a largely unknown underlying biology. In a genome-wide association study of CTS (48,843 cases and 1,190,837 controls), we found 53 sequence variants at 50 loci associated with the syndrome. The most significant association is with a missense variant (p.Glu366Lys) in SERPINA1 that protects against CTS (P = 2.9 × 10^-24, OR = 0.76). Through various functional analyses, we conclude that at least 22 genes mediate CTS risk and highlight the role of 19 CTS variants in the biology of the extracellular matrix. We show that the genetic component to the risk is higher in bilateral/recurrent/persistent cases than nonrecurrent/nonpersistent cases. Anthropometric traits including height and BMI are genetically correlated with CTS, in addition to early hormonal-replacement therapy, osteoarthritis, and restlessness. Our findings suggest that the components of the extracellular matrix play a key role in the pathogenesis of CTS.

A genetic risk score and diabetes predict development of alcohol-related cirrhosis in drinkers

BACKGROUND & AIMS

Only a minority of excess alcohol drinkers develop cirrhosis. We developed and evaluated risk stratification scores to identify those at highest risk.

METHODS

Three cohorts (GenomALC-1: n = 1,690, GenomALC-2: n = 3,037, UK Biobank: relevant n = 6,898) with a history of heavy alcohol consumption (≥80 g/day (men), ≥50 g/day (women), for ≥10 years) were included. Cases were participants with alcohol-related cirrhosis. Controls had a history of similar alcohol consumption but no evidence of liver disease. Risk scores were computed from up to 8 genetic loci identified previously as associated with alcohol-related cirrhosis and 3 clinical risk factors. Score performance for the stratification of alcohol-related cirrhosis risk was assessed and compared across the alcohol-related liver disease spectrum, including hepatocellular carcinoma (HCC).

RESULTS

A combination of 3 single nucleotide polymorphisms (SNPs) (PNPLA3:rs738409, SUGP1-TM6SF2:rs10401969, HSD17B13:rs6834314) and diabetes status best discriminated cirrhosis risk. The odds ratios (ORs) and (95% CIs) between the lowest (Q1) and highest (Q5) score quintiles of the 3-SNP score, based on independent allelic effect size estimates, were 5.99 (4.18-8.60) (GenomALC-1), 2.81 (2.03-3.89) (GenomALC-2), and 3.10 (2.32-4.14) (UK Biobank). Patients with diabetes and high risk scores had ORs of 14.7 (7.69-28.1) (GenomALC-1) and 17.1 (11.3-25.7) (UK Biobank) compared to those without diabetes and with low risk scores. Patients with cirrhosis and HCC had significantly higher mean risk scores than patients with cirrhosis alone (0.76 ± 0.06 vs. 0.61 ± 0.02, p = 0.007). Score performance was not significantly enhanced by information on additional genetic risk variants, body mass index or coffee consumption.

CONCLUSIONS

A risk score based on 3 genetic risk variants and diabetes status enables the stratification of heavy drinkers based on their risk of cirrhosis, allowing for the provision of earlier preventative interventions.

LAY SUMMARY

Excessive chronic drinking leads to cirrhosis in some people, but so far there is no way to identify those at high risk of developing this debilitating disease. We developed a genetic risk score that can identify patients at high risk. The risk of cirrhosis is increased >10-fold with just two risk factors - diabetes and a high genetic risk score. Risk assessment using this test could enable the early and personalised management of this disease in high-risk patients.

Characterizing the risk interplay between alcohol intake and body mass index on cirrhosis morbidity

BACKGROUND AND AIMS

It is thought that alcohol intake and body mass index (BMI) interact supra-additively to modulate the risk of cirrhosis, but evidence for this phenomenon is limited. We investigated the interrelationship between alcohol and BMI on the incidence of cirrhosis morbidity for participants of the United Kingdom Biobank (UKB) study.

APPROACH AND RESULTS

The primary outcome was the cumulative incidence of cirrhosis morbidity, defined as a first-time hospital admission for cirrhosis (with noncirrhosis mortality incorporated as a competing risk). All UKB participants without a previous hospital admission for cirrhosis were included in the analysis. We determined the ratio of the 10-year cumulative incidence in harmful drinkers versus safe drinkers according to BMI. We also calculated the excess cumulative incidence at 10 years for individuals with obesity and/or harmful alcohol compared to safe drinkers with a healthy BMI of 20-25.0 kg/m² . A total of 489,285 UK Biobank participants were included, with mean of 10.7 person-years' follow-up. A total of 2070 participants developed the primary outcome, equating to a crude cumulative incidence of 0.36% at 10 years (95% CI:0.34-0.38). The 10-year cumulative incidence was 8.6 times higher for harmful (1.38%) versus safe drinkers (0.16%) if BMI was healthy. Conversely, it was only 3.6 times higher for obese participants (1.99% vs. 0.56%). Excess cumulative incidence was 1.22% (95% CI:0.89-1.55) for harmful drinkers with a healthy BMI, 0.40% (95% CI:0.34-0.46) for obese individuals drinking at safe levels, and 1.83% (95% CI:1.46-2.20) for obese harmful drinkers (all compared to safe drinkers with a healthy BMI).

CONCLUSIONS

Alcohol intake and obesity are independent risk factors for cirrhosis morbidity, but they do not interact supra-additively to modulate the cumulative incidence of this outcome.

Genome-Wide Association Study of NAFLD Using Electronic Health Records

Genome-wide association studies (GWAS) have identified several risk loci for nonalcoholic fatty liver disease (NAFLD). Previous studies have largely relied on small sample sizes and have assessed quantitative traits. We performed a case-control GWAS in the UK Biobank using recorded diagnosis of NAFLD based on diagnostic codes recommended in recent consensus guidelines. We performed a GWAS of 4,761 cases of NAFLD and 373,227 healthy controls without evidence of NAFLD. Sensitivity analyses were performed excluding other co-existing hepatic pathology, adjusting for body mass index (BMI) and adjusting for alcohol intake. A total of 9,723,654 variants were assessed by logistic regression adjusted for age, sex, genetic principal components, and genotyping batch. We performed a GWAS meta-analysis using available summary association statistics. Six risk loci were identified (P < 5*10-8 ) (apolipoprotein E [APOE], patatin-like phospholipase domain containing 3 [PNPLA3, transmembrane 6 superfamily member 2 [TM6SF2], glucokinase regulator [GCKR], mitochondrial amidoxime reducing component 1 [MARC1], and tribbles pseudokinase 1 [TRIB1]). All loci retained significance in sensitivity analyses without co-existent hepatic pathology and after adjustment for BMI. PNPLA3 and TM6SF2 remained significant after adjustment for alcohol (alcohol intake was known in only 158,388 individuals), with others demonstrating consistent direction and magnitude of effect. All six loci were significant on meta-analysis. Rs429358 (P = 2.17*10-11 ) is a missense variant within the APOE gene determining ϵ4 versus ϵ2/ϵ3 alleles. The ϵ4 allele of APOE offered protection against NAFLD (odds ratio for heterozygotes 0.84 [95% confidence interval 0.78-0.90] and homozygotes 0.64 [0.50-0.79]). Conclusion: This GWAS replicates six known NAFLD-susceptibility loci and confirms that the ϵ4 allele of APOE is associated with protection against NAFLD. The results are consistent with published GWAS using histological and radiological measures of NAFLD, confirming that NAFLD identified through diagnostic codes from consensus guidelines is a valid alternative to more invasive and costly approaches.

Diagnostic challenges in patients with alcohol-related liver disease

Alcohol is globally the leading risk factor for cirrhosis and is subsumed under the term alcohol-related liver disease (ALD). However, only ca. 10% of people with harmful alcohol consumption (>40 gram alcohol per day) develop cirrhosis, while 15% have normal liver histology. Unfortunately, laboratory parameters and ultrasound hold little value to neither rule-in nor rule out alcohol related liver fibrosis. While several indices with combinations of liver associated markers such as FIB4 seem to be promising, non-invasive test strategies are urgently needed with cut-off's that can be applied to guide clinical decision making. The aims of this review article are to highlight novel developments for the diagnosis of ALD and to identify topics of controversy and potential future directions. In the last 15 years, elastography to measure liver stiffness (LS) has significantly improved our screening strategies for cirrhosis. LS values below 6 kPa are considered as normal and exclude ALD. LS of 8 and 12.5 kPa represent generally accepted cut-off values for F3 and F4 fibrosis. Especially, transient elastography (TE) has been assessed in numerous studies, but similar performance can be obtained with point shear wave elastography, 2 SD shear wave elastography or MR elastography. Important confounders of elevated LS such as inflammation should also be considered and alcohol withdrawal not only improves liver inflammation but also LS. Liver stiffness measurement has signficiantly improved early diagnosis and follow-up of fibrosis in patients with ALD and patients with diagnosed manifest but clinically compensated cirrhosis should undergo further clinical examinations to rule out complications of portal hypertension. In addition, surveillance for the occurrence of hepatocellular carcinoma is recommended in all cirrhotic patients.