Autosomal-recessive mutations in a tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase (TRMU, OMIM*610230, also known as MTU1, MTO2), which is responsible for the 2-thiouridylation of mt-tRNAGlu, mt-tRNAGln and mt-tRNALys, but not of any other mt-tRNAs cause a severe but reversible infantile hepatopathy (7,8). This evidence concerns the gene TRMU and Decreased liver function.