Early-onset diabetes with low utilization of lipid as an energy source carrying a rare missense mutation in the CEL gene

The CEL gene encodes the digestive enzyme carboxyl ester lipase, also known as bile salt-stimulated/dependent lipase. CEL is expressed in pancreatic acinar tissue but not in pancreatic β cells. MODY caused by mutations in the CEL gene (MODY8) is characterized by dominantly inherited diabetes mellitus manifesting in early adulthood. A classical feature of MODY8 is pancreatic exocrine dysfunction, often with onset in childhood. Known pathogenic mutations in the CEL gene affect the variable number tandem repeat (VNTR) region in exon 11. Our case suggests that some missense mutations of the CEL VNTR could have a phenotypic implication by being associated with impaired glucose-stimulated insulin secretion and reduced utilization of lipid as an energy source which leads to MASLD.