Gene therapy: current status.

The bone marrow is the probable first target for gene therapy of genetic diseases. The candidate diseases are those involving mutant enzymes, such as adenosine deaminase. A consensus strategy has evolved utilizing RNA viral vectors to introduce new genes into marrow cells. Two major obstacles still preclude application of this technology to humans: extremely inefficient expression of a new gene in the host cell, and the lack of a convenient and clinically acceptable method of returning the genetically altered cells to the patient. Even before the technical problems of gene therapy have been solved, other technologies such as organ transplantation, are helping to ease the burden of many genetic diseases.