Gene therapies using HSCT have been developed for Fabry.  The method involves harvesting the Hematopoietic Stem Cells (HSCs) from a patient (autologous) and then genetically engineering the cells to express the missing alpha-galactosidase A, via a lentiviral vector engineered to express protein from the GLA gene. These Lentiviral transduced cells are verified by PCR for transgene levels prior to their reintroduction into the patient. Before reintroduction, the patient is conditioned by treatment with melphalan in an outpatient setting to remove a portion of the remaining HSCs in the patient (submyloablative) and make room for the genetically-engineered HS cells to thrive (engraftment). To perform the engraftment, the GLA-expressing HSCs are reintroduced into the submyloablated patient and the patient is monitored for levels of engraftment by PCR of Peripheral Blood Mononuclear Cells (PBMCs). Levels of gene function in PBMCs are monotored by by GLA enzyme activity assay and the levels of toxic metabolites (lyso-GB3 and GB3) are measured in PBMCs by mass spectrometry and platereader methods. In phase 1 clinical studies performed in Canada, gene therapy with HSCTs were found to be safe and had secondary endpoints of long durability, which was giving patient the ability to live for many years without the need to return to tradition ERT injection treatments.