Differing genetic variants associated with liver fat and their contrasting relationships with cardiovascular diseases and cancer

Triglyceride to High-Density Lipoprotein Cholesterol Ratio as a Marker of Subclinical Coronary Atherosclerosis and Hepatic Steatosis in Familial Hypercholesterolemia

OBJECTIVE

Features of the cardiometabolic syndrome are prevalent in patients with familial hypercholesterolemia (FH). Triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio, a surrogate marker of insulin resistance, may be a robust predictor of cardiac events in the general population. We explored the association between TG/HDL-C ratio and high-risk coronary artery plaque (HRP) and hepatic steatosis (HS) in asymptomatic patients with FH.

METHODS

We conducted a cross-sectional study of 290 patients (mean age = 49 years, 44% male) who underwent computed tomography coronary angiography for cardiovascular risk assessment. HRP and HS were assessed from computed tomography coronary angiography, and TG/HDL-C ratio was derived from the fasting lipid panel collected around time of scanning. Associations were assessed using binary logistic and Kaplan-Meier analysis.

RESULTS

TG/HDL-C ratio was significantly associated with HRP (odds ratio, 1.27; 95% CI, 1.04-1.56; P = .020) and HS (odds ratio, 1.71; 95% CI, 1.17-2.51; P = .005) after adjusting for age, body mass index, smoking, and coronary calcium score. TG/HDL-C ratio was associated with HRP in patients treated with lipid-lowering medications (P = .042) and inclusion in a predictive model outperformed the FH-Risk-Score (area under receiver operating characteristic 0.74 vs 0.63; P = .004). An elevated TG/HDL-C ratio predicted myocardial infarction or coronary revascularization over a median follow-up of 91 months with 10 cardiac events recorded (P = .043). TG/HDL-C ratio was strongly positively correlated (P < .001 for all) with markers of cardiometabolic dysfunction: lipid accumulation product (r = 0.81), visceral adiposity index (r = 0.96), and triglyceride-glucose index (r = 0.91).

CONCLUSION

TG/HDL-C ratio was strongly associated with HRP, HS, and cardiac events in patients with FH treated with long-term cholesterol-lowering therapy.

Associations of Alcohol Consumption and Genetic Predisposition to Hepatic Steatosis With Liver-Related Events: Results From Large Population-Based Cohort Studies

BACKGROUND & AIMS

The new classification for steatotic liver disease identifies 3 phenotypes based on alcohol consumption. The aim of this study was to evaluate the associations between alcohol intake and liver-related events (LREs) across different drinking categories and whether genetic predisposition influences these associations.

METHODS

Data from 301,673 UK Biobank participants were analyzed. Alcohol consumption was self-reported and categorized by weekly intake as mild (< 140 g for females and < 210 g for males), moderate (140-350 g for females and 210-420 g for males), and heavy (> 350 g in females and > 420 g for males). A polygenic risk score based on 5 well-known single nucleotide polymorphisms associated with hepatic steatosis was calculated. Hazard ratios (HRs) and 95% CIs were calculated using Cox proportional hazard models. The analysis was validated in 47,252 participants from China Kadoorie Biobank.

RESULTS

During a median follow-up of 12.8 years, 1742 incident cases of LREs were documented. The multivariable-adjusted HRs per SD increment in alcohol intake for LREs were 0.95 (95% CI, 0.89-1.02) among mild drinkers, 1.23 (95% CI, 1.10-1.37) among moderate drinkers, and 1.18 (95% CI, 1.14-1.22) among heavy drinkers. The associations appeared stronger in those with high genetic risk. Compared with adults with low genetic risk and mild alcohol consumption, those with high genetic risk and heavy alcohol consumption had higher risks of LREs (HR, 6.50; 95% CI, 5.26-8.04; P for interaction < .001). Similar findings were observed in China Kadoorie Biobank.

CONCLUSIONS

Associations between alcohol intake and LREs vary across different drinking categories. Individuals with a higher genetic risk for steatotic liver disease appear more susceptible to alcohol.

Clinical staging to guide management of metabolic disorders and their sequelae: a European Atherosclerosis Society consensus statement

Obesity rates have surged since 1990 worldwide. This rise is paralleled by increases in pathological processes affecting organs such as the heart, liver, and kidneys, here termed systemic metabolic disorders (SMDs). For clinical management of SMD, the European Atherosclerosis Society proposes a pathophysiology-based system comprising three stages: Stage 1, where metabolic abnormalities such as dysfunctional adiposity and dyslipidaemia occur without detectable organ damage; Stage 2, which involves early organ damage manifested as Type 2 diabetes, asymptomatic diastolic dysfunction, metabolic-associated steatohepatitis (MASH), and chronic kidney disease (CKD); and Stage 3, characterized by more advanced organ damage affecting multiple organs. Various forms of high-risk obesity, driven by maintained positive energy balance, are the most common cause of SMD, leading to ectopic lipid accumulation and insulin resistance. This progression affects various organs, promoting comorbidities such as hypertension and atherogenic dyslipidaemia. Genetic factors influence SMD susceptibility, and ethnic disparities in SMD are attributable to genetic and socioeconomic factors. Key SMD features include insulin resistance, inflammation, pre-diabetes, Type 2 diabetes, MASH, hypertension, CKD, atherogenic dyslipidaemia, and heart failure. Management strategies involve lifestyle changes, pharmacotherapy, and metabolic surgery in severe cases, with emerging treatments focusing on genetic approaches. The staging system provides a structured approach to understanding and addressing the multi-faceted nature of SMD, which is crucial for improving health outcomes. Categorization of SMD abnormalities by presence and progression is aimed to improve awareness of a multi-system trait and encourage a tailored and global approach to treatment, ultimately aiming to reduce the burden of obesity-related comorbidities.

Human genetics of metabolic dysfunction-associated steatotic liver disease: from variants to cause to precision treatment

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by increased hepatic steatosis with cardiometabolic disease and is a leading cause of advanced liver disease. We review here the genetic basis of MASLD. The genetic variants most consistently associated with hepatic steatosis implicate genes involved in lipoprotein input or output, glucose metabolism, adiposity/fat distribution, insulin resistance, or mitochondrial/ER biology. The distinct mechanisms by which these variants promote hepatic steatosis result in distinct effects on cardiometabolic disease that may be best suited to precision medicine. Recent work on gene-environment interactions has shown that genetic risk is not fixed and may be exacerbated or attenuated by modifiable (diet, exercise, alcohol intake) and nonmodifiable environmental risk factors. Some steatosis-associated variants, notably those in patatin-like phospholipase domain-containing 3 (PNPLA3) and transmembrane 6 superfamily member 2 (TM6SF2), are associated with risk of developing adverse liver-related outcomes and provide information beyond clinical risk stratification tools, especially in individuals at intermediate to high risk for disease. Future work to better characterize disease heterogeneity by combining genetics with clinical risk factors to holistically predict risk and develop therapies based on genetic risk is required.

PNPLA3 I148M and Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. With the widespread implementation of HBV vaccination and the availability of highly effective antiviral therapies, the incidence of metabolic dysfunction-associated steatotic liver disease (MASLD)-related HCC has proportionally increased. Notably, up to 20%-30% of MASLD-related HCC cases develop in the absence of overt cirrhosis. Several genetic variants, primarily in genes related to lipid metabolism, play a key role in HCC development in individuals with MASLD and alcohol-related liver disease. Among these, the rs738409 C>G polymorphism (I148M) in the patatin-like phospholipase domain-containing protein 3 (PNPLA3) gene is the strongest genetic factor predisposing to the entire spectrum of MASLD conditions, including cirrhosis and HCC. Importantly, combining PNPLA3 I148M with multiple genetic variants robustly associated with progressive liver disease (i.e., polygenic risk scores) improves risk stratification and prediction of HCC in at-risk individuals compared to the single variant alone. In this review, we will discuss the latest evidence on the epidemiology of HCC and the contribution of PNPLA3 and PNPLA3-based polygenic risk scores to the development of HCC in at-risk individuals.

Heterogeneous effects of genetic variants and traits associated with fasting insulin on cardiometabolic outcomes

Elevated fasting insulin levels (FI), indicative of altered insulin secretion and sensitivity, may precede type 2 diabetes (T2D) and cardiovascular disease onset. In this study, we group FI-associated genetic variants based on their genetic and phenotypic similarities and identify seven clusters with distinct mechanisms contributing to elevated FI levels. Clusters fall into two types: "non-diabetogenic hyperinsulinemia," where clusters are not associated with increased T2D risk, and "diabetogenic hyperinsulinemia," where T2D associations are driven by body fat distribution, liver function, circulating lipids, or inflammation. In over 1.1 million multi-ancestry individuals, we demonstrated that diabetogenic hyperinsulinemia cluster-specific polygenic scores exhibit varying risks for cardiovascular conditions, including coronary artery disease, myocardial infarction (MI), and stroke. Notably, the visceral adiposity cluster shows sex-specific effects for MI risk in males without T2D. This study underscores processes that decouple elevated FI levels from T2D and cardiovascular risk, offering new avenues for investigating process-specific pathways of disease.

Metabolic dysfunction-associated steatotic liver disease: heterogeneous pathomechanisms and effectiveness of metabolism-based treatment

The global epidemic of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing worldwide. People with MASLD can progress to cirrhosis and hepatocellular carcinoma and are at increased risk of developing type 2 diabetes, cardiovascular disease, chronic kidney disease, and extrahepatic cancers. Most people with MASLD die from cardiac-related causes. This outcome is attributed to the shared pathogenesis of MASLD and cardiometabolic diseases, involving unhealthy dietary habits, dysfunctional adipose tissue, insulin resistance, and subclinical inflammation. In addition, the steatotic and inflamed liver affects the vasculature and heart via increased glucose production and release of procoagulant factors, dyslipidaemia, and dysregulated release of hepatokines and microRNAs. However, there is substantial heterogeneity in the contributors to the pathophysiology of MASLD, which might influence its rate of progression, its relationship with cardiometabolic diseases, and the response to therapy. The most effective non-pharmacological treatment approaches for people with MASLD include weight loss. Paradoxically, some effective pharmacological approaches to improve liver health in people with MASLD are associated with no change in bodyweight or even with weight gain, and similar response heterogeneity has been observed for changes in cardiometabolic risk factors. In this Review, we address the heterogeneity of MASLD with respect to its pathogenesis, outcomes, and metabolism-based treatment responses. Although there is currently insufficient evidence for the implementation of precision medicine for risk prediction, prevention, and treatment of MASLD, we discuss whether knowledge about this heterogeneity might help achieving this goal in the future.

Recent advances in MASLD genetics: Insights into disease mechanisms and the next frontiers in clinical application

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease in the world and a growing cause of liver-related morbidity and mortality. Yet, at the same time, our understanding of the pathophysiology and genetic underpinnings of this increasingly common yet heterogeneous disease has increased dramatically over the last 2 decades, with the potential to lead to meaningful clinical interventions for patients. We have now seen the first pharmacologic therapy approved for the treatment of MASLD, and multiple other potential treatments are currently under investigation-including gene-targeted RNA therapies that directly extend from advances in MASLD genetics. Here we review recent advances in MASLD genetics, some of the key pathophysiologic insights that human genetics has provided, and the ways in which human genetics may inform our clinical practice in the field of MASLD in the near future.

TM6SF2 -rs58542926 Genotype Has Opposing Effects on Incidence of Hepatic and Cardiac Events in a Community Cohort

INTRODUCTION

TM6SF2 -rs58542926-T is associated with increased cirrhosis and modestly decreased coronary artery disease prevalence. However, relative effects of TM6SF2 genotype on major adverse cardiovascular events (MACE) vs liver-related events (LRE) are not known.

METHODS

We used the UK Biobank, a prospective cohort with genetic and inpatient diagnosis data. The primary predictor was TM6SF2 -rs58542926 genotype, and the primary outcomes were MACE and LRE. Effects were reported as subhazard ratios (sHRs) and 10-year cumulative incidence by Fine-Gray competing risk analyses.

RESULTS

More than 430,000 individuals met inclusion criteria. TM6SF2 -rs58542926-TT genotype (vs CC) was associated with higher incidence of LRE (adjusted sHR 3.16, 95% confidence interval 1.86-5.37) and lower incidence of MACE (adjusted sHR for TT vs CC genotype 0.76, 95% confidence interval 0.63-0.91). In individuals with fibrosis-4 (FIB4) < 1.3, 1.3-2.67, and > 2.67, 10-year LRE incidence in TM6SF2 -rs58542926-TT vs CC individuals was 0.08% vs 0.06% ( P > 0.05), 0.81% vs 0.20% ( P < 0.0001), and 10.5% vs 3.4% ( P = 0.00094), respectively. The corresponding values for MACE were 3.8% vs 5.1% ( P = 0.032), 6.4% vs 8.2% ( P = 0.040), and 17.1% vs 12.4% ( P > 0.05). The absolute decrease in MACE with rs58542926-TT (vs CC) genotype exceeded the absolute increase in LRE in all groups but FIB4 > 2.67. Associations of TM6SF2 genotype with LRE/MACE were significant in men but not women. TM6SF2 -rs58542926-T allele was also associated with increased hepatic steatosis and corrected T1 time by magnetic resonance imaging, with greater effect sizes in men than women.

DISCUSSION

TM6SF2 genotype has opposite effects on LRE vs MACE incidence, and absolute effects on MACE were greater except in those with highest FIB4 scores. Effects were strongest in men. These findings clarify implications of TM6SF2 genotype based on personalized clinical risk.