Clinical application of gene therapy: emerging opportunities and current limitations.

Protocols for human gene therapy have been approved and a number of investigative trials are in place. While somatic gene therapy is favored over germline therapy, it must be recognized that transformation of somatic cells may occur inadvertently. Ex vivo and in vivo approaches offer two different strategies for genetic intervention and are discussed in the context of therapy for inborn errors of metabolism, brain tumors and other neurological diseases, and AIDS and other infectious diseases. Current technology appears quite promising, but serious limitations remain before routine application of gene therapy is possible.