3-methylglutaconic aciduria (3-MGA) type IV, or unclassified 3-MGA, is a clinically heterogeneous disorder characterized by increased 3-methylglutaconic acid excretion in individuals that cannot be classified as having one of the other forms of 3-MGA (3-MGA I, II or III). The disease is 3-methylglutaconic aciduria type 4 (MONDO_0009611). Also known as: 3-methylglutaconic aciduria type IV, MGA type IV, MGA4, MGCA4.