Should scientists alter the germline of humans?

On December 3rd, a group of scientists from leading research organizations met in Washington, DC to discuss a controversial topic, editing the human germline. Changing these genes would result in heritable changes to the human genome – changes that could be passed on from parents to their children.

Convened by the Institute of Medicine, the Royal Society of London, the US National Academy of Sciences and the Chinese Academy of Sciences, the meeting considered moral ramifications and safety issues similar to the Asilomar Conference held in 1975. Led by Dr. Paul Berg, the Asilomar Conference considered the safety of what was then an emerging technique – recombinant DNA technology.

The participating scientists at the DC conference, led by Dr. David Baltimore, recommended a moratorium on editing the human germline. Making alterations to the human germline is not a simple endeavor; however, a recent new technique, CRISPR-Cas9, has made targeted gene editing simpler and more accurate. The CRISPR-Cas9 technique is a wonderful breakthrough that enables great advances in biological research for a wide range of applications, including plant studies; however, concerns have been expressed over using the technology for the human germline, which has occurred (albeit the embryos had a chromosomal defect rendering them unviable) at a university in China.

The international group of scientists discussed many aspects of the ability to efficiently alter the genes in egg and sperm cells. This could potentially be used not only to cure genetic disease, but also to alter physical traits for “designer babies”.

Gene therapy vs. Gene editing

Currently gene therapy is used to treat and even cure some genetic conditions. In these cases, however, body tissues or cells are altered but not the egg or sperm, so the alterations made by gene therapy are not passed down to the treated person’s offspring. Gene therapy is a very powerful technique that is just now beginning to show effectiveness – a few drugs are in clinical trials, such as Bluebird Bio’s LentiGlobin® BB305, a treatment showing promise for beta thalassemia.

Calling for a discussion

Earlier, in March of this year, a group of scientists from the biotechnology industry, including authors from the Alliance for Regenerative Medicine, wrote an editorial in the journal Nature, suggesting that “scientists should agree not to modify the DNA of human reproductive cells” and encouraging an “open discussion around the appropriate course of action”.

Two recent articles in MIT Technology Review discuss embryonic gene editing with leading researchers in the field and explore some of the research being done in this area.

Legislation currently exists in certain countries that prevents editing the heritable germline of human embryos. The organizations meeting recently on December 3rd have no legislative power, but morally they have the ability to influence researchers. As of now, the group would like more discussion and asks researchers to proceed with care regarding human germline gene editing until it can be better evaluated and a consensus is reached.