Gene therapy appears to be one of the most controversial branches of contemporary medicine – both exceedingly promising and highly risky. Three latest decades of its rapid development have seen polar scientific and public responses to the practice and brought both encouraging and alerting results. Within the limits of this research paper, we will investigate the achievements of gene therapy in the field of genetic disorders treatment making necessary flashbacks to the time of first applications of gene therapy whose results have become obvious now.

In 1998, the symposium “The Human Genome Project: Science, Law, and Social Change in the 21st Century” held in Cambridge, Massachusetts, described gene therapy as “a novel approach in its very early stages” (James Wilson). The two main types of gene therapy were explained at the symposium. The first type involves operating on somatic (body) cells, while the second one implies working with germ (egg or sperm) cells. Unlike germline, somatic gene therapy does not suggest passing along the alteration of the cell to the next generation.

Eric Lander of Whitehead Institute of Biomedical Research claimed at the symposium that we were the contemporaries of a discovery as great as Mendeleev’s periodic table of 1869 – the 100,000 human genes were being listed and organized. Not only should this achievement offer a multitude of new opportunities for biological sciences and industry, but it should also help us perceive the vast diversity of the human race and find cure for many diseases.

The gene therapy of the mid-1980s mainly concentrated on treating monogenic defects, i.e. such diseases of blood cells as hemophilia, Duchenne’s muscular dystrophy, sickle cell anemia, and β-thalassemia. They were to present fruitful material for experimenting since their nature was thoroughly studied at the molecular level and the target cell, i.e. the hematopoietic stem cell, was easily accessible for explantation, genetic correction and retransplantation. A strong argument in favor of gene therapy over the conventional transplantation of hematopoietic stem cells from compatible donors was the fact that gene therapy could be applied to all patients as it allowed to avoid problems of the immunologic barriers fraught with graft rejection or graft-versus-host disease. But the technical difficulties of correcting hemoglobin disorders by means of gene therapy soon appeared formidable; in fact, gene transfer was to be performed in high numbers of hematopoietic stem sells and high levels of expression of the β-globin gene in erythrocyte precursors.

In contrast, by the late 1980s and early 1990s the effects of gene therapy were tested on a number of acquired diseases. Unfortunately, there are some tragic pages in the history of gene therapy. For instance, in July 2007, 36-year-old Jolee Mohr died arguably as a result of participating in a gene-therapy clinical trial about her rheumatoid arthritis. Before receiving gene therapy treatment, she was able to lead an active life keeping her disease under control due to conventional drugs. A sudden infection that spread just after the experimental treatment and caused her organs to fail led to her untimely death associated by many with the effect of gene therapy. Naturally, the event invited much doubt in the extent to which applying gene therapy methods is justifiable in case of non-terminal diseases that are not progressing and can be otherwise controlled.

It was in the mid-1980s that several groups of scientists got interested in gene therapy for a rare genetic disorder – severe combined immunodeficiency disease (SCID) due to deficiency of the enzyme adenosine deaminase (ADA). This disease, widely known as “boy in the bubble syndrome”, is a disorder which cripples both B cells and T cells of the adaptive immune system because of a defective gene. Thus, SCID presents a severe form of heritable immunodeficiency. Its popular name “bubble boy” disease is to highlight the vulnerability of SCID-sufferers to various infectious diseases. They tend to have chronic diarrhea, ear infections, recurrent Pneumocystis jirovecii and profuse oral candidiasis. If babies born with SCID due to ADA deficiency do not receive proper treatment, they die within one year of recurrent infections. In Australia, one in 65,000 live newborn babies is reported to have SCID. According to recent studies, one in every 2,500 Navajo children get severe combined immunodeficiency from their parents and it is an important cause of illness and death for the Navajo. A similar genetic pattern appears active among the related Apache people.