Since January, a new California law allows for a child to have more than two legal parents. But children are still limited to two genetic parents. That could change soon, if the Food and Drug Administration approves human clinical trials for a technique known as mitochondrial replacement, which would enable a child to inherit DNA from three parents.
News of the pending application has caused a kind of panic not seen since Dolly the sheep was cloned, raising the possibility of a single genetic parent. But far from being the end of the human race as we know it, the technique might be a way to prevent hundreds of mitochondrial-linked diseases, which affect about one in 5,000 people.
The idea of multi-person reproductive collaborations is not new. Over the last several decades we have acclimated to various forms of assisted reproductive technologies. Indeed, in the U.S. about 75,000 infants are born each year to parents who enlist the aid of egg donors, sperm donors or gestational carriers. These methods, however, still involve the "traditional" merger of DNA from one male and one female.
Mitochondrial replacement would alter this two-genetic-parent model by introducing a third set of DNA into the procreative process. The technique would enable women who carry harmful mutations in their mitochondria to have a child without those harmful mutations. As with all human reproduction, the child would carry a combination of genes from one male and one female. However, in this technique, the nucleus of the mother's egg would be injected into a "third parent's" nucleus-free egg containing healthy mitochondrial DNA. As a result, the child would inherit the characteristics of the original male and female but have healthy mitochondria from a third person.
Experiments employing the technique conducted on monkeys resulted in healthy offspring that did not carry the harmful mutation. Now, a team at Oregon Health and Sciences University is seeking approval from the FDA to begin human clinical trials.
It seems likely that, if it is proved safe and effective, mitochondrial replacement will eventually join the panoply of techniques facilitating the birth of healthy children through assisted conception. But it should be no surprise that the new technology is causing a furor.
The introduction of assisted reproductive technologies has followed a predictable pattern: initial panic followed by widespread condemnation, followed by gradual acceptance as a technique becomes more widespread. In the 1950s, when reports of pregnancies using donor sperm first appeared in medical journals, lawmakers declared the process "mechanical adultery" and sought its criminalization. Early reports of success with in vitro fertilization in the 1970s provoked editorials that decried the process as totally immoral. In the 1990s, the introduction of pre-implantation diagnosis of genetic diseases provoked allegations of a war on disabled individuals.
Today, detractors remain, but the methods have been embraced as the standard of care in reproductive medicine. Once a technique proves safe and effective, its ability to assist in the birth of healthy children generally paves the way for public approval.
For some, the introduction of a third genetic parent is alarming because the novel genetic configuration could be embedded in the child's DNA in perpetuity, with unknown implications for future generations. But the panic also rests in part on simple discomfort with upending the notion of genetic parenthood involving just two people.
A similar anxiety seized the public this year after California authorized judges to recognize more than two people as a child's lawful parents. The law grew out of a horrendous situation in which the court's inability to recognize a third parent diverted a young child into foster care. Though it's hardly on par with the scientific breakthrough represented by mitochondrial replacement, the so-called three-parent law stirred deep fears about the durability of traditional family life in the modern era.
But the fears about three-parent possibilities — both genetic and legal — are likely to subside as people realize that they are aimed at one goal: the well-being of children. The California law orders judges to recognize three parents when not doing so "would otherwise be detrimental to the child." And mitochondrial replacement will be employed to avoid transmission of a heritable disease. If the "power of three" has the ability to improve a child's well-being, isn't that something worth embracing?
Judith Daar is a visiting professor at the UC Irvine School of Law, a clinical professor at the UC Irvine School of Medicine and a professor at Whittier Law School. Erez Aloni is an assistant professor at Whittier Law School.