Update in lean metabolic dysfunction-associated steatotic liver disease

BACKGROUND A new nomenclature consensus has emerged for liver diseases that were previously known as non-alcoholic fatty liver disease(NAFLD)and metabolic dysfunction-associated fatty liver disease(MAFLD).They are now defined as metabolic dysfunction-associated steatotic liver disease(MASLD),which includes cardiometabolic criteria in adults.This condition,extensively studied in obese or overweight patients,constitutes around 30%of the population,with a steady increase worldwide.Lean patients account for approximately 10%-15%of the MASLD population.However,the pathogenesis is complex and is not well understood.AIM To systematically review the literature on the diagnosis,pathogenesis,characteristics,and prognosis in lean MASLD patients and provide an interpretation of these new criteria.METHODS We conducted a comprehensive database search on PubMed and Google Scholar between January 2012 and September 2023,specifically focusing on lean NAFLD,MAFLD,or MASLD patients.We include original articles with patients aged 18 years or older,with a lean body mass index categorized according to the World Health Organization criteria,using a cutoff of 25 kg/m2 for the general population and 23 kg/m2 for the Asian population.RESULTS We include 85 studies in our analysis.Our findings revealed that,for lean NAFLD patients,the prevalence rate varied widely,ranging from 3.8%to 34.1%.The precise pathogenesis mechanism remained elusive,with associations found in genetic variants,epigenetic modifications,and adaptative metabolic response.Common risk factors included metabolic syndrome,hypertension,and type 2 diabetes mellitus,but their prevalence varied based on the comparison group involving lean patients.Regarding non-invasive tools,Fibrosis-4 index outperformed the NAFLD fibrosis score in lean patients.Lifestyle modifications aided in reducing hepatic steatosis and improving cardiometabolic profiles,with some medications showing efficacy to a lesser extent.However,lean NAFLD patients exhibited a worse prognosis compared to the obese or overweight counterpart.CONCLUSION MASLD is a complex disease comprising epigenetic,genetic,and metabolic factors in its pathogenesis.Results vary across populations,gender,and age.Limited data exists on clinical practice guidelines for lean patients.Future studies employing this new nomenclature can contribute to standardizing and generalizing results among lean patients with steatotic liver disease.

Evolution of liver transplantation in the metabolic dysfunctionassociated steatotic liver disease era: Tracking impact through time

Liver transplantation(LT)for metabolic dysfunction-associated steatotic liver disease(MASLD)is increasing globally due to rising rates of obesity and metabolic syndrome,posing significant challenges.MASLD patients typically present with advanced age,higher body mass index(BMI),and metabolic com-orbidities such as diabetes,hypertension,and dyslipidemia.Comprehensive pre-transplant evaluations are crucial for assessing surgical risks and preparing patients for transplantation.MASLD patients with higher BMI may experience longer operative times,potentially affecting intraoperative outcomes.In the months following LT,MASLD recipients face persistent challenges,including a higher incidence of metabolic syndrome and cardiovascular events compared to non-MASLD recipients.However,survival rates at 1-,3-,and 5-years post-LT do not markedly differ from other etiologies,indicating comparable surgical outcomes.Optimizing outcomes in MASLD patients undergoing LT demands a multidisciplinary approach from pre-transplant assessment to post-transplant care.Strategies must address metabolic comorbidities,manage cardiovascular health,and monitor steatosis recurrence,which can be exacerbated by obesity and diabetes.This approach aims to mitigate long-term graft complications and mortality risks,ultimately enhancing transplant success and patient well-being.Continued research is essential to refine these approaches and meet the evolving challenges posed by MASLD as a leading indication for LT worldwide.