When transferred to germ-free (GF) mice through cecal microbiota transplantation, the microbiome signature of MCJ KO mice exerted beneficial effects and delayed NASH progression mice by enhancing fatty acid oxidation, SCFA, nicotinamide adenine dinucleotide (NAD+) metabolism, and sirtuin activity. The gene discussed is DNAJC15; the disease is metabolic dysfunction-associated steatohepatitis.