1Gene TherapyGene therapy: the attempt to cure an underlying genetic problem by insertion of a correct copy of a gene.Tantalizingly simple and profound in theory, maddeningly difficult to actually achieve.Easiest targets: access to or retrieval of cellsespiratory and bloodEngineered virus, infects cells, carries in good gene.Engineer cell in tube, return to body.!ecent successes"denosine #eaminase deficiency#efect in nucleoside metabolism especially affects $hite blood cells%&lin'ed chronic granulomatous disease(eutrophils fail to ma'e supero)ideGeneral scheme: etrovirus used to replace gene in bone marro$ cells, return cells to patient *+ailuresGenes don,t al$ays ma'e into genome-cure. is short&lived as #(" disappears/iruses carrying genes insert in bad places0ause over&e)pression of genes or #(" deletions0ancer1mmune system becomes sensitized to vector#eath of patient in clinical trial in 1222.3(e$ development4leeping 5eauty transposon system+irst transposon available in vertebrates67riginally from inactive fish transposonEngineer $ith gene of interestTransposon inserts $ith gene, getting it into the chromosome1nserts in different places from viral vector8uch higher rate of gene insertion94leeping 5eauty Transposon system"ctive transposon engineered from an inactive fish transposon.Transposon :umps into chromosome bringing good gene $ith it.http:;;$$$.discoverygenomics.net;sbts.html