GSTZ1 gene is a member of the glutathione S-transferase (GSTs) super-family which encodes multifunctional enzymes important in the detoxification of electrophilic molecules, including carcinogens, mutagens, and several therapeutic drugs, by conjugation with glutathione. GSTZ1 is a bifunctional protein which has minimal glutathione-conjugating activity with ethacrynic acid and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole and maleylacetoacetate isomerase activity. GSTZ1 catalyzes the glutathione dependent oxygenation of dichloroacetic acid to glyoxylic acid. GSTZ1 participates in the catabolism of phenylalanine and tyrosine. Thus defects in GSTZ1 cause harsh metabolic disorders including alkaptonuria, phenylketonuria and tyrosinaemia.