[Clinical gene therapy: genes by prescription?]

Gene therapy is a medical intervention based on modification of the genetic material of living cells. This technique offers widespread possibilities in treating or preventing diseases. This applies to genetically determined diseases but also to diseases that occur later in life. Cells may be modified ex vivo for subsequent administration to patients, or may be altered in vivo by gene therapy given directly to the subject. To introduce the genetic material in cells, vectors are being used. Currently, most vectors are from viral origin. This requires special precautions when producing viral vectors. Gene therapy is apparently safe, when the proper indications and contra-indications are taken into account. Expectations regarding gene therapy are very high. However, more technological barriers are encountered than foreseen and therefore, the clinical success up to now is limited.