Unique genetic variants of lean nonalcoholic fatty liver disease: a retrospective cohort study

Revisiting the causal impact of lipid traits on metabolic dysfunction-associated fatty liver disease: Insights from a multidimensional plasma lipid profile

AIMS

Recent advancements in plasma lipidomes genome-wide association studies data have enhanced our understanding of lipid categories, significantly improving risk assessments for metabolic dysfunction-associated fatty liver disease (MAFLD) beyond traditional lipid biomarkers.

MATERIALS AND METHODS

This study utilized Mendelian randomization (MR) to assess the causal relationships between 179 lipid species across 13 subclasses and MAFLD, primarily using the Wald ratio and IVW methods. Corrections were made using false discovery rate (FDR), supplemented by Bayesian colocalization analysis.

RESULTS

Elevated levels of genetically predicted phosphatidylcholine (16:0_16:1) [ORWald ratio = 2.638, 95% CI 1.557-4.469, P = 3.11 × 10-4], phosphatidylcholine (16:1_18:0) (ORWald ratio = 2.644, 95% CI 1.559-4.486, P = 3.11 × 10-4), triacylglycerol (46:2) (ORWald ratio = 2.515, 95% CI 1.524-4.153, P = 3.11 × 10-4), and triacylglycerol (48:2) (ORIVW = 1.863, 95% CI 1.300-2.669, P = 6.95 × 10-4) were significantly associated with increased MAFLD risk, with rs1260326 within the GCKR gene playing a crucial role. Colocalization analysis indicated that in significant evidences, the posterior probability for hypothesis 4 was over 80%, identifying rs780093 as a shared causal variant. Additionally, 16 suggestive evidences were identified.

CONCLUSION

The study confirmed the significant role of specific lipid molecules in influencing MAFLD risk, providing new scientific bases and potential therapeutic targets for future treatment strategies.

Appendicular skeletal muscle mass is associated with metabolic dysfunction-associated steatotic liver disease severity in young men: a cross-sectional and longitudinal study

BACKGROUND AND AIM

Although appendicular skeletal muscle mass (ASM) has been linked to the severity of hepatic steatosis, investigations of its correlation among younger age groups are lacking. We aimed to elucidate the role of ASM in determining the severity of metabolic dysfunction-associated steatotic liver disease (MASLD) in younger patients.

METHODS

Retrospective data were collected from patients younger than 35 years who visited the Armed Forces Goyang Hospital between June 2022 and February 2024. Steatosis presence was determined by a controlled attenuation parameter score ≥ 250 dB/m, and significant fibrosis was identified with liver stiffness measurement > 8.0 kPa. ASM was measured using multifrequency bioelectrical impedance analysis (InBody 620).

RESULTS

Of 910 participants, 630 were diagnosed with MASLD. Patients with MASLD had lower ASM/fat mass (ASM/F) (1.02 vs. 1.91; p < 0.001), ASM/body mass index (BMI) (0.91 vs. 1.04/m2; p < 0.001), and ASM/body weight (ASM/W) (29.5% vs. 33.8%; p < 0.001) than non-MASLD patients. Additionally, ASM/F, ASM/BMI, and ASM/W significantly decreased with worsening steatosis severity and were notably lower in patients with significant fibrosis. Among 107 patients with MASLD who underwent two examinations with a median interval of 6.0 months, those with increased ASM/F showed a higher proportion of steatosis regression and a lower proportion of steatosis worsening than those with decreased ASM/F (steatosis regression, 43.1% vs. 22.9%; worsening, 11.1% vs. 28.6%; p = 0.031). All three ASM indices were significant factors in steatosis regression during the study period.

CONCLUSIONS

ASM is associated with the severity of steatosis and significant fibrosis in MASLD in young adults < 35 years.

What Is New in Metabolic Dysfunction-Associated Steatotic Liver Disease in Lean Individuals: From Bench to Bedside

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects more than 30% of the world's adult population. While it is associated with obesity and metabolic syndrome, emerging evidence has shown that a substantial number of MASLD patients have a normal body mass index ("lean individuals with MASLD"). In this article, we provide an overview of the definition, epidemiology, pathogenesis, and clinical outcomes associated with lean individuals with MASLD and updates on current management.

Genetic and epigenetic determinants of non-alcoholic fatty liver disease (NAFLD) in lean individuals: a systematic review

Background

Non-alcoholic fatty liver disease (NAFLD) is common in obese individuals, but its occurrence in lean individuals and the underlying mechanisms are not well understood. This study aimed to systematically review the literature on the genetic and epigenetic factors influencing NAFLD in lean individuals.

Methods

A comprehensive search was conducted on April 2nd, 2023, in seven databases using specific criteria. Only peer-reviewed studies in English, focusing on genetic or epigenetic effects on NAFLD in lean individuals, were included for qualitative synthesis. The Newcastle Ottawa Scale (NOS) was used for quality assessment. This study is registered with PROSPERO (CRD42023413809).

Results

Following PRISMA guidelines, 18 studies were included in this review. The studies were conducted globally, with varying sample sizes and study designs. The NOS quality assessment revealed a moderate overall quality with variations in risk of bias and limitations in comparability and ascertainments of exposure among contributing studies. Genetic determinants related to lipid metabolism, inflammation, and oxidative stress pathways were identified, including PNPLA3 and TM6SF2 gene variants associated with increased NAFLD risk in lean individuals. Epigenetic modifications, particularly depletion of histone variants, were also implicated. However, some studies found no significant associations between genetic or clinical characteristics and lean NAFLD. Less frequent genetic risk factors, such as CETP and APOC3 gene variants, were reported.

Conclusions

This systematic review underscores the importance of investigating genetic and epigenetic factors in lean NAFLD. The findings highlight the role of PNPLA3 and TM6SF2 gene variants and suggest potential epigenetic contributions. Further research is needed to fully understand the genetic and epigenetic mechanisms underlying NAFLD in lean individuals.

Lean nonalcoholic fatty liver disease and sarcopenia

Nonalcoholic fatty liver disease (NAFLD) has become one of the most common chronic liver diseases in the world. The risk factor for NAFLD is often considered to be obesity, but it can also occur in people with lean type, which is defined as lean NAFLD. Lean NAFLD is commonly associated with sarcopenia, a progressive loss of muscle quantity and quality. The pathological features of lean NAFLD such as visceral obesity, insulin resistance, and metabolic inflammation are inducers of sarcopenia, whereas loss of muscle mass and function further exacerbates ectopic fat accumulation and lean NAFLD. Therefore, we discussed the association of sarcopenia and lean NAFLD, summarized the underlying pathological mechanisms, and proposed potential strategies to reduce the risks of lean NAFLD and sarcopenia in this review.