TYMP and mitochondrial neurogastrointestinal encephalomyopathy: TP-deficient B-lymphoblastoid cells from MNGIE patients and partially myeloablated double TYMP/UPP1 knockout mice have been transfected with lentiviral or adeno-associated virus (AAV) vectors carrying the TYMP coding sequence with a reduction in nucleoside concentrations [18], [19].