In the case of lentivirus-based gene therapy, a lentiviral vector carrying the human pyruvate kinase deficiency (hPKD) promoter and the PKLR gene was employed for addressing the monogenic metabolic disease PKD caused by mutations in the pyruvate kinase isoenzymes L/R (PKLR) gene [49]. The gene discussed is PKLR; the disease is Hemolytic anemia due to red cell pyruvate kinase deficiency.