Mayo Clinic researchers have identified a rare mutation in the MET gene that directly causes metabolic dysfunction-associated steatotic liver disease (MASLD).[1][2] This mutation impairs the liver's ability to process fat, leading to inflammation, scarring, and potentially cirrhosis.[1][2] The discovery began with a father and daughter who had the disease without common risk factors such as obesity or diabetes.[1] The specific mutation is NM000245.4:c.3505A>T; p.(Ile1169Phe) in the kinase domain of the MET gene.[2] In an analysis of data from 3904 patients with steatotic liver disease (SLD), 1.1% (45/3904) had rare deleterious variants in the MET gene.[2] Of these, 17.7% (8/45) had variants in the kinase domain similar to the familial case.[2] The study confirms the first nonmalignant monogenic form of SLD caused by a MET mutation and highlights the importance of genomic data.[1][2]