[Gene therapy--hopes and fears].

Gene therapy assumes the correction of a genetic defect by the delivery of a correct DNA sequence to the target cells. Depending on the target cells two types gene therapy have been defined: somatic and germinal. By July 1998, 351 protocols of somatic therapy were approved by the Recombinant DNA Advisory Committee. The majority of protocols focus on cancer therapy and monogenic diseases. By now, still there is more unfulfilled expectation than clinically sound achievements, since no effective prevention or successful treatment for genetic diseases or cancer have been developed. Germline genetic modification is considered as the treatment of choice for such a diseases like retinoblastoma. Tay-Sachs, Lesch-Nyhan and metachromatic leuko-dystrophy. This approach which is still illegal or prohibited by rules in many European countries, is gathering more and more advocates. Once we learn how to control gene expression the perspectives for clinical application of gene therapy might be enormous. The safety of genetic modification of gametes or embryonal stem cells remains to be properly addressed and successfully solved. The ethical issues of germinal gene therapy are still the subject of controversial opinions among the scientists, lawyers and philosophers.