This Core will serve as the central PCR diagnostic laboratory to evaluate the efficacy of the different strategies implemented in the scientific projects (Projects 1-3) and to monitor the overall progress of the clinical trial (Project). This will be accomplished by verifying the transduction efficiency of stem cells; establishing the presence of an active expression of the therapeutic gene in these cells; detecting the presence and long- term expression of the transduced retroviral vectors in patient samples, and by evaluating the antiviral activity of the ribozyme in conjunction with tests done in Project 2. Importance of Core to IPCP Program. The critical endpoint determination, namely the presence of ribozyme transgene in transduced cells, will be determined by this Core for the scientific projects and for the two gene therapy trials.