Recent advances in medicine and genetic technology make it possible to treat human disease by altering the genes in cells of the sufferer. Though the methods of the emerging field of genetic medicine are still under development, the pace of clinical trials and recent advances suggests that gene therapy will become a common and versatile medical option. This prospect highlights the need for Christians to identify the moral principles of their faith that apply to the practice of human gene therapy.
Gene therapy employs DNA or RNA, the chemicals that make up genes, to cure or ameliorate inherited defects or acquired diseases. The therapeutic genetic material may be designed to replace defective genes in the patient's cells or to provide supplementary genetic information to regulate the function of normal genes. The DNA may come from almost any source--animals, plants, microbes, viruses--or it may be synthetic with no counterpart in nature. The effect of the introduced material may be intentionally temporary or it may be permanent. Often the results achieved by gene therapy cannot be obtained by any other means. The diseases that were first considered for gene therapy were relatively uncommon inherited conditions. Subsequently the focus moved to genetic treatments for common ailments--cancer, heart disease, hypertension, diabetes, etc.
Discovering efficient ways to introduce genes into a large number of the particular cells that would most benefit from them has been the technical challenge limiting the usefulness of gene therapy. In most clinical tests, viruses are used as "vectors" or "vehicles" to carry the new DNA because viruses are incredibly efficient at infecting cells with their own genes. A virus vector is typically constructed by removing genes that the virus would use to replicate or to damage its host cells, and replacing them with therapeutic genes. Adenoviruses (cold viruses), retroviruses (relatives of HIV), adeno-associated virus (a small virus not known to cause disease), herpes virus and several others have been used in various cases. All virus vectors have characteristics that limit their usefulness and there is often a medical risk involved in their use. Other means for inserting genes into cells that do not involve viruses may also be developed, but non-viral methods are generally less effective.
Somatic Gene Therapy
Categories of gene therapy are defined by the heritability of the changes they cause. Somatic gene therapy alters genes in cells that may be located anywhere in the body, except the reproductive cells. Many different organs have been proposed as targets--bone marrow, liver, muscle, skin, lungs, blood vessels, heart, brain. However, somatic therapy conscientiously avoids making genetic change that may be transmitted to the offspring of the patient. Consequently, this form of gene therapy has the same goal as conventional medicine--to save the life or relieve the suffering of the treated individual.
Somatic gene therapy is divided into two classes depending upon how new genes are introduced. In many situations cells are first removed from the patient and then treated in the laboratory, a procedure often called ex vivo gene therapy. After the genetic modification has been accomplished, the cells are returned to the patient in the hope that they will take up residence in the target tissue in sufficient numbers to achieve the desired effect. Because ex vivo protocols must be individually designed for each person, they are labor-intensive and costly. A current objective is to accomplish genetic modification in vivo, by introducing therapeutic genes directly into the patient. At present, none of the available vehicles can seek out intended target cells effectively and inject their cargo of genes with sufficient efficiency to achieve the desired effect.
Though there have been many clinical trials of somatic therapy, few have been unambiguously successful. The techniques for introducing therapeutic genes into body cells are still primitive, inefficient, and potentially hazardous. The death of one young patient in a clinical trial in late 1999 demonstrated that an adequate level of safety had not been achieved.
Germline Gene Therapy
In contrast to somatic gene therapy, germline therapy purposely makes genetic changes that extend to the reproductive cells. As a result, the change may be inherited by the offspring of the original patient. Thus, germline therapy deliberately attempts to improve not only the condition of the patient, but also his or her descendants for generations to come. In this respect it represents a fundamentally new objective for medical intervention. It offers the potential advantage of eliminating the cause of a debilitating condition, as opposed to separately treating affected individuals in each successive generation.
The technique involves the precise manual introduction of DNA into individual fertilized eggs or into the cells of embryos at a very early stage of development. At present, germline modifications have been accomplished only in animals. In addition to the health hazards it shares with advanced reproductive technologies,1 germline therapy is associated with a high risk of embryonic and fetal death, stillbirth and infant death, physical abnormalities and genetic defects. Beyond the fundamental issue of safety, germline therapy raises serious ethical concerns. These include the problem of informed consent from individuals not yet born, assessing the long-term consequences of genetic alterations, the possible reduction of human diversity by systematic elimination of specific traits, genetic determinism imposed by the choices of the original patient and genetic therapists, the prospect that germline therapy may be used in eugenics programs, and the problematic issue of using it to engineer cosmetic enhancements. Because of the unresolved safety and ethical issues, germline therapy is widely discouraged or prohibited.
While gene therapy is still in its infancy, it is our moral responsibility as thoughtful Christians to become aware of its potential to meet human needs, to understand the biological and genetic risks that it entails, and to avoid its misuse. Decisions in this complex and evolving area should be in harmony with the following biblical principles:
1. Alleviating suffering and preserving life. The Bible portrays God as endlessly concerned with the health, well-being, and restoration of his creatures (Prov 3:1-8; Ps 103:2, 3; Matt 10:29-31, 11:4, 5; Acts 10:38; John 10:10). He explicitly commands us to continue His healing ministry (Matt 10:1; Luke 9:2). To the extent that gene therapy can prevent genetic disease and restore health, it should be welcomed as a means for cooperating with the divine initiative to relieve avoidable suffering.
2. Safety, protection from harm. The Scriptures charge us to defend the vulnerable in society (Deut 10:17-19; Ps 9:9; Isa 1:16-17; Matt 25:31-46; Luke 4:18, 19). Where disease or genetic disorder is not life-threatening, genetic intervention may be considered only when a high level of safety has been achieved and life is protected at all stages of development. Even in situations where life is at stake, the risks involved in genetic intervention must be amply balanced by the prospects for healing.
3. Honoring God's image. Human beings, created in the image of God (Gen 1:26, 27), are distinct in kind and degree from all other earthly creatures, with God-given abilities to reason, appreciate spiritual values, and make moral decisions (1 Kings 3:9; Dan 2:20-23;
Phil 4:8, 9; Ps 8:3-8; Eccl 3:10, 11, modern version). Great caution must attend any action that would permanently change the human genome in ways that affect these capacities.
4. Protecting human autonomy. God places a high value on human freedom
(Deut 30:15-20; Gen 4:7). Genetic alterations that would limit an individual's abilities, restrict participation in society, reduce autonomy, or undermine personal freedom must be rejected.
5. Understanding God's creation. Since God endowed human beings with intelligence and creativity, He intends for them to take responsibility over His creation (Gen 1:28) and to grow in their understanding of the principles of life, including the function of their bodies (Matt 6:26-29; 1 Cor 14:20; Ps 8:3-9; 139:1-6; 13-16). Ethical research and examination can only increase our appreciation of God's wisdom and goodness.
1Refer to CVHLC statement "Considerations on Assisted Human Reproduction," July 26, 1994.
This document was adopted by the General Conference Christian View of Human Life Committee in April, 2000, and was referred to those Church departments and institutions which will find the material useful.