The CIDEB (Cell Death Inducing DFFA Like Effector B) gene encodes a lipid transferase protein that is predominantly expressed in the liver, but also found in significant levels in the small intestine, colon, kidney, and spleen. This protein primarily localizes to the cytosol, perinuclear region of the cytoplasm, and specifically to lipid droplets and the endoplasmic reticulum, where it plays a critical role in lipid metabolism by promoting the fusion of lipid droplets to form larger unilocular droplets, thereby favoring lipid storage and restricting lipolysis ^[1]. CIDEB is also essential for the lipidation and maturation of very-low-density lipoproteins (VLDLs) and chylomicrons, facilitating their transport ^[2]. Beyond lipid metabolism, CIDEB has been implicated in the positive regulation of apoptosis, though its basal expression levels do not typically induce cell death ^[3]. Furthermore, CIDEB influences the replication cycle of hepatitis C virus (HCV) and hepatitis B virus (HBV), acting as a cofactor for HCV entry into hepatocytes ^[4]. Associated diseases include various liver conditions such as metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction-associated steatohepatitis (MASH), cirrhosis, and viral hepatitis (HCV, HBV), with rare germline loss-of-function variants in CIDEB demonstrating a protective effect against these liver diseases ^[5].

The B6-hCIDEB mouse is a humanized model, constructed by replacing the sequences from exon 1 to partial intron 2 of mouse Cideb with the Human CIDEB genomic region (exon 1 to exon 5)-rBG pA cassette. B6-hCIDEB mice can be used for research into the pathogenesis of various liver conditions, such as metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction-associated steatohepatitis (MASH), cirrhosis, and viral hepatitis (HCV, HBV). They are also useful for the screening, development, and safety evaluation of CIDEB-targeted drugs.