The invention relates to mRNA therapy for the treatment of Citrullinemia Type 2 ("CTLN2"). mRNAs for use in the invention, when administered in vivo, encode human Citrin, isoforms thereof, functional fragments thereof, and fusion proteins comprising Citrin. mRNAs of the invention are preferably encapsulated in lipid nanoparticles (LNPs) to effect efficient delivery to cells and/or tissues in subjects, when administered thereto. mRNA therapies of the invention increase and/or restore deficient levels of Citrin expression and/or activity in subjects. mRNA therapies of the invention further decrease levels of biomarkers associated with deficient Citrin activity in subjects, namely ammonia and/or triglycerides.
