GSTM3 (Glutathione S-Transferase Mu 3) is a gene that encodes an enzyme from the glutathione S-transferase family, which is responsible for detoxifying harmful substances. It plays a crucial role in metabolising carcinogens, medications, and by-products of oxidative stress. Variations in GSTM3 may affect an individual’s susceptibility to cancer, neurodegenerative diseases, and other conditions linked to detoxification pathways.