Effect of common genetic variants on the risk of cirrhosis in non-alcoholic fatty liver disease during 20 years of follow-up

Are we ready for genetic testing in metabolic dysfunction-associated steatotic liver disease?

Metabolic dysfunction-associated steatotic liver disease (MASLD), with its steadily increasing prevalence, represents now a major problem in public health. A proper referral could benefit from tools allowing more precise risk stratification. To this end, in recent decades, several genetic variants that may help predict and refine the risk of development and progression of MASLD have been investigated. In this review, we aim to discuss the role genetics in MASLD plays in everyday clinical practice. We performed a comprehensive literature search of PubMed for relevant publications. Available evidence highlights the emergence of genetic-based noninvasive algorithms for diagnosing fatty liver, metabolic dysfunction-associated steatohepatitis, fibrosis progression and occurrence of liver-related outcomes including hepatocellular carcinoma. Nevertheless, their accuracy is not optimal and application in everyday clinical practice remains challenging. Furthermore, susceptible genetic markers have recently become subjects of great scientific interest as therapeutic targets in precision medicine. In conclusion, decisional algorithms based on genetic testing in MASLD to facilitate the clinician decisions on management and treatment are under growing investigation and could benefit from artificial intelligence methodology.

Risk of major adverse liver outcomes among first-degree relatives of individuals with MASLD

BACKGROUND & AIMS

Previous studies have suggested an increased risk of major adverse liver outcomes (MALO) in relatives of patients with metabolic dysfunction-associated steatotic liver disease (MASLD). However, granular and longitudinal evidence is lacking on the future risk of MALO among family members of individuals with MASLD.

METHODS

We identified 3526 first-degree relatives (FDRs) and 11 079 general population comparators to 1328 patients with MASLD diagnosed between 1974 and 2021, with detailed clinical data, including liver histology in 71% of patients. MALO was defined through diagnostic coding for cirrhosis or its complications. Cox regression models were used to estimate adjusted hazard ratios (aHRs) for MALO among FDRs compared to general population comparators. Cumulative incidence accounting for competing risks was calculated.

RESULTS

During a median follow-up of 13.4 years, there were 65 (2%, 1.12/1000 person-years) and 225 (2%, 1.26/1000 person-years) MALO events in FDRs and general population comparators respectively. After adjusting for demographic factors and comorbidities, FDRs were at no increased risk of MALO (aHR = 0.99, 95% CI: 0.74-1.33). Increased relative rates of MALOs were, however, observed in some subgroups, including parents, although absolute risk estimates were low and comparable to the general population.

CONCLUSIONS

FDRs of patients with MASLD did not have a higher rate of incident MALO than the general population. Since the absolute risk of MALO in relatives of patients with MASLD was low, these results do not support systematic screening of MASLD-related fibrosis in relatives of patients with MASLD.

PNPLA3 rs738409, age, diabetes, sex, and advanced fibrosis jointly contribute to the risk of major adverse liver outcomes in metabolic dysfunction-associated steatotic liver disease

BACKGROUND AND AIMS

The patatin-like phospholipase domain-containing protein 3 ( PNPLA3 ) rs738409 variant is associated with steatotic liver disease and its progression. We examined the association between PNPLA3 and the development of major adverse liver outcomes (MALOs) and how nonmodifiable and modifiable conditions modify this relationship.

APPROACH AND RESULTS

A total of 2075 adults with biopsy-confirmed metabolic dysfunction-associated steatotic liver disease (MASLD) were enrolled in the metabolic dysfunction-associated steatohepatitis Clinical Research Network (MASH CRN) studies and followed prospectively until death, transplant, or withdrawal of consent. One hundred four MALOs were recorded during an average of 4.3 years. PNPLA3 G-allele (Adj. sub-hazard ratio (sHR): 1.4, 95% CI: 1.07-1.8), advanced fibrosis (AF) (Adj. sHR: 7.8, 95% CI: 4.4-13.8), age >60 years (Adj. sHR: 2.9, 95% CI: 1.3-6.8), and type 2 diabetes mellitus (Adj. sHR: 2.8, 95% CI: 1.8-4.2) were associated with MALO. Among participants with AF, those carrying the G-allele displayed the highest cumulative incidence of MALO (85%) versus noncarriers (53%), p =0.03, and p -value for interaction <0.01. The strength of the association between PNPLA3 and MALO was statistically significantly greater among older than 60 years (sHR: 2.1, 95% CI: 1.5-2.8), women (sHR: 1.4, 95% CI: 1.1-1.9), and those with AF (sHR: 1.9, 95% CI: 1.5-2.4) or type 2 diabetes mellitus (sHR: 2.1, 95% CI: 1.5-2.8) as compared with their counterparts, p -value for interaction between PNPLA3 and each factor<0.01.

CONCLUSIONS

The deleterious effects of PNPLA3 rs738409 on the risk of MALO are significantly worsened by AF, age, type 2 diabetes mellitus, and sex.

Global epidemiology of type 2 diabetes in patients with NAFLD or MAFLD: a systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and metabolic-associated fatty liver disease (MAFLD) shares common pathophysiological mechanisms with type 2 diabetes, making them significant risk factors for type 2 diabetes. The present study aimed to assess the epidemiological feature of type 2 diabetes in patients with NAFLD or MAFLD at global levels.

METHODS

Published studies were searched for terms that included type 2 diabetes, and NAFLD or MAFLD using PubMed, EMBASE, MEDLINE, and Web of Science databases from their inception to December 2022. The pooled global and regional prevalence and incidence density of type 2 diabetes in patients with NAFLD or MAFLD were evaluated using random-effects meta-analysis. Potential sources of heterogeneity were investigated using stratified meta-analysis and meta-regression.

RESULTS

A total of 395 studies (6,878,568 participants with NAFLD; 1,172,637 participants with MAFLD) from 40 countries or areas were included in the meta-analysis. The pooled prevalence of type 2 diabetes among NAFLD or MAFLD patients was 28.3% (95% confidence interval 25.2-31.6%) and 26.2% (23.9-28.6%) globally. The incidence density of type 2 diabetes in NAFLD or MAFLD patients was 24.6 per 1000-person year (20.7 to 29.2) and 26.9 per 1000-person year (7.3 to 44.4), respectively.

CONCLUSIONS

The present study describes the global prevalence and incidence of type 2 diabetes in patients with NAFLD or MAFLD. The study findings serve as a valuable resource to assess the global clinical and economic impact of type 2 diabetes in patients with NAFLD or MAFLD.

MBOAT7 in liver and extrahepatic diseases

MBOAT7 is a protein anchored to endomembranes by several transmembrane domains. It has a catalytic dyad involved in remodelling of phosphatidylinositol with polyunsaturated fatty acids. Genetic variants in the MBOAT7 gene have been associated with the entire spectrum of non-alcoholic fatty liver (NAFLD), recently redefined as metabolic dysfunction-associated fatty liver disease (MAFLD) and, lately, steatotic liver disease (SLD), and to an increasing number of extrahepatic conditions. In this review, we will (a) elucidate the molecular mechanisms by which MBOAT7 loss-of-function predisposes to MAFLD and neurodevelopmental disorders and (b) discuss the growing number of genetic studies linking MBOAT7 to hepatic and extrahepatic diseases. MBOAT7 complete loss of function causes severe changes in brain development resulting in several neurological manifestations. Lower MBOAT7 hepatic expression at both the mRNA and protein levels, due to missense nucleotide polymorphisms (SNPs) in the locus containing the MBOAT7 gene, affects specifically metabolic and viral diseases in the liver from simple steatosis to hepatocellular carcinoma, and potentially COVID-19 disease. This body of evidence shows that phosphatidylinositol remodelling is a key factor for human health.

An integrated gene-to-outcome multimodal database for metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the commonest cause of chronic liver disease worldwide and represents an unmet precision medicine challenge. We established a retrospective national cohort of 940 histologically defined patients (55.4% men, 44.6% women; median body mass index 31.3; 32% with type 2 diabetes) covering the complete MASLD severity spectrum, and created a secure, searchable, open resource (SteatoSITE). In 668 cases and 39 controls, we generated hepatic bulk RNA sequencing data and performed differential gene expression and pathway analysis, including exploration of gender-specific differences. A web-based gene browser was also developed. We integrated histopathological assessments, transcriptomic data and 5.67 million days of time-stamped longitudinal electronic health record data to define disease-stage-specific gene expression signatures, pathogenic hepatic cell subpopulations and master regulator networks associated with adverse outcomes in MASLD. We constructed a 15-gene transcriptional risk score to predict future hepatic decompensation events (area under the receiver operating characteristic curve 0.86, 0.81 and 0.83 for 1-, 3- and 5-year risk, respectively). Additionally, thyroid hormone receptor beta regulon activity was identified as a critical suppressor of disease progression. SteatoSITE supports rational biomarker and drug development and facilitates precision medicine approaches for patients with MASLD.

Glucokinase regulatory protein: a balancing act between glucose and lipid metabolism in NAFLD

Non-alcoholic fatty liver disease (NAFLD) is a common liver disease worldwide, affected by both genetics and environment. Type 2 diabetes (T2D) stands as an independent environmental risk factor that precipitates the onset of hepatic steatosis and accelerates its progression to severe stages of liver damage. Furthermore, the coexistence of T2D and NAFLD magnifies the risk of cardiovascular disease synergistically. However, the association between genetic susceptibility and metabolic risk factors in NAFLD remains incompletely understood. The glucokinase regulator gene (GCKR), responsible for encoding the glucokinase regulatory protein (GKRP), acts as a regulator and protector of the glucose-metabolizing enzyme glucokinase (GK) in the liver. Two common variants (rs1260326 and rs780094) within the GCKR gene have been associated with a lower risk for T2D but a higher risk for NAFLD. Recent studies underscore that T2D presence significantly amplifies the effect of the GCKR gene, thereby increasing the risk of NASH and fibrosis in NAFLD patients. In this review, we focus on the critical roles of GKRP in T2D and NAFLD, drawing upon insights from genetic and biological studies. Notably, prior attempts at drug development targeting GK with glucokinase activators (GKAs) have shown potential risks of augmented plasma triglycerides or NAFLD. Conversely, overexpression of GKRP in diabetic rats improved glucose tolerance without causing NAFLD, suggesting the crucial regulatory role of GKRP in maintaining hepatic glucose and lipid metabolism balance. Collectively, this review sheds new light on the complex interaction between genes and environment in NAFLD, focusing on the GCKR gene. By integrating evidence from genetics, biology, and drug development, we reassess the therapeutic potential of targeting GK or GKRP for metabolic disease treatment. Emerging evidence suggests that selectively activating GK or enhancing GK-GKRP binding may represent a holistic strategy for restoring glucose and lipid metabolic balance.

Higher mortality among lean patients with non-alcoholic fatty liver disease despite fewer metabolic comorbidities

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) can develop in individuals who are not overweight. Whether lean persons with NAFLD have lower mortality and lower incidence of cirrhosis, cardiovascular diseases (CVD), diabetes mellitus (DM) and cancer than overweight/obese persons with NAFLD remains inconclusive. We compared mortality and incidence of cirrhosis, CVD, DM and cancer between lean versus non-lean persons with NAFLD.

METHODS

This is a retrospective study of adults with NAFLD in a single centre from 2012 to 2021. Primary outcomes were mortality and new diagnosis of cirrhosis, CVD, DM and cancer. Outcomes were modelled using competing risk analysis and Cox proportional hazards regression analysis.

RESULTS

A total of 18,594 and 13,420 patients were identified for cross-sectional and longitudinal analysis respectively: approximately 11% lean, 25% overweight, 28% class 1 obesity and 35% class 2-3 obesity. The median age was 51.0 years, 54.6% were women. The median follow-up was 49.3 months. Lean patients had lower prevalence of metabolic diseases at baseline and lower incidence of cirrhosis and DM than non-lean patients and no difference in CVD, any cancer or obesity-related cancer during follow-up. However, lean patients had significantly higher mortality with incidence per 1000 person-years of 16.67, 10.11, 7.37 and 8.99, respectively, in lean, overweight, obesity class 1 and obesity class 2-3 groups respectively.

CONCLUSIONS

Lean patients with NAFLD had higher mortality despite lower incidence of cirrhosis and DM, and similar incidence of CVD and cancer and merit similar if not more attention as non-lean patients with NAFLD.

Screening for NAFLD-Current Knowledge and Challenges

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of abnormal liver function tests worldwide, with an estimated prevalence ranging between 19-46% in the general population. Of note, NAFLD is also expected to become a leading cause of end-stage liver disease in the next decades. Given the high prevalence and severity of NAFLD, especially in high-risk populations (i.e., patients with type-2 diabetes mellitus and/or obesity), there is a major interest in early detection of the disease in primary care. Nevertheless, substantial uncertainties still surround the development of a screening policy for NAFLD, such as limitations in currently used non-invasive markers of fibrosis, cost-effectiveness and the absence of a licensed treatment. In this review, we summarise current knowledge and try to identify the limitations surrounding the screening policy for NAFLD in primary care.

Development of LXR inverse agonists to treat MAFLD, NASH, and other metabolic diseases

Activation of LXR activity by synthetic agonists has been the focus of many drug discovery efforts with a focus on treatment of dyslipidemia and atherosclerosis. Many agonists have been developed, but all have been hindered due to their ability to efficaciously stimulate de novo lipogenesis. Here, we review the development of LXR inverse agonists that were originally optimized for their ability to enable recruitment of corepressors leading to silencing of genes that drive de novo lipogenesis. Such compounds have efficacy in animal models of MAFLD, dyslipidemia, and cancer. Several classes of LXR inverse agonists have been identified and one is now in clinical trials for treatment of severe dyslipidemia.