Mitochondrial Replacement: Science, Ethics, and Policy in a New Age of Genetic Medicine

Abstract

Mitochondrial disease, which is caused by mutations in genes encoded by the mitochondria located within the body’s cells, can be devastating and lethal. Mitochondria, which are inherited maternally, produce the body’s energy. Symptoms of mutations manifest themselves in a number of ways, making mitochondrial disease difficult to diagnose and treat. In recent years, scientists have sought ways to prevent mitochondrial disease. One solution, called mitochondrial replacement, involves injecting the nucleus from the egg of a woman with mitochondrial disease into the cytoplasm of a healthy donor enucleated egg. When successful, this technique can eliminate mitochondrial disease in the child that is born and in all subsequent generations. In the United States and the United Kingdom, discussions to judge whether to legalize this procedure are underway and must consider both scientific and ethical issues. First, policy makers need to evaluate the procedure’s safety and efficacy to ensure that children born via this procedure as well as future generations will be healthy. Next, they must weigh the ethical issues raised, from the precedent of crossing the germ line to the implications of creating a child with genetic information from three individuals. Finally, both the US and the UK have existing legal frameworks dictating how mitochondrial replacement is currently treated. In the US, the procedure would require an Investigational New Drug permit from the Food and Drug Administration (FDA) to proceed with clinical trials. In the UK, there are explicit laws forbidding this procedure because it manipulates embryos. To investigate whether Parliament should change these laws, the Human Fertilisation and Embryology Authority (HFEA) formed advisory committees to inform the government. As a result, Parliament voted at the beginning of 2015 to permit this procedure in clinics licensed by the HFEA. My analysis of the scientific and ethical aspects of the procedure reveals that mitochondrial replacement should be permitted since the benefits outweigh the risks. But to address concerns about the procedure and its future implications, regulations must be put into place to guarantee that this procedure and others in the future that would modify the nuclear or mitochondrial genome are ethically grounded. For example, in the case of mitochondrial replacement, it should only be used to prevent mitochondrial disease and not as an infertility treatment. This will set a precedent that procedures like this that manipulate the genome are only acceptable to prevent very serious disease. Next, the mitochondrial donor should be treated as a tissue donor and not as a third parent. This is technically correct, given the very small amount of genetic information that the donor will contribute. This will also reduce confusion about the procedure for the general public. Finally, governments should fund and support this research so that they can be involved in oversight. This will ensure that scientists and clinics are adhering to protocols and using the procedure as they should. Mitochondrial replacement and the laws surrounding it can set a precedent for procedures involving genetic manipulation. While the procedure should be permitted, policy makers must be aware of the significance of their choices as they craft specific regulations.