A few successes notwithstanding, gene therapy remains highly experimental. Only a limited number of rare genetic diseases are candidates for gene therapy, and a few recipients have experienced severe adverse reactions from the treatment. Critics have argued that the technique has fallen short of its expectations.
Nevertheless, proof-of-principle studies showing that severe combined immunodeficiencies (SCID) can be corrected in a sustained way for a patient's benefit have been published.1,2 Some 20 patients now live as a direct result of genetic interventions. For the field to progress, and for that number to rise, we must learn from these successes what we did right, and from failure what went wrong. Only then can we make gene therapy safe enough and effective enough to become a routine component of the medical response to genetic diseases.
Though their causes vary, severe combined immunodeficiencies all are marked by a patient's inability to produce the T ...
