Histologic severity is identical between normal weight and overweight adults with MASLD: Implications for the definition of lean MASLD

INTRODUCTION While higher body weight is closely associated with histologic severity in metabolic-associated steatotic liver disease (MASLD), lean MASLD (ie, MASLD in normal weight individuals) is a relatively distinct phenotype that has received considerable attention.1,2 However, there are knowledge gaps in our understanding of the interplay among weight categories, PNPLA3 genotype, and severity of liver histology. While there have been studies done previously to evaluate the interaction between body mass index (BMI) and MASLD severity, these have been somewhat limited by smaller study size and lack of liver histology.3,4 In this study, we examined clinical, PNPLA3 genotypic, and histological characteristics of MASLD across several BMI categories in 3386 adult participants of the NASH Clinic Research Network. METHODS We collected data for adult patients enrolled in various prospective studies between October 2004 and May 2024 at 9 participating NASH Clinic Research Network centers. Participants provided written informed consent. All patients had a liver biopsy centrally reviewed by the NASH Clinic Research Network Pathology Committee. Weight and height were measured at the screening visit and were the average of 2 measurements. We divided patients into the following BMI categories: normal weight (BMI