D. Joy Riley, M.D., M.A.
What is it?
Imagine a word processor for genes, where you could search for a defective gene, find the mutation, cut it out, and replace it with the proper DNA sequence. The cutting and replacing part of the process is what CRISPR and its associated (Cas) systems do. They are enzymes used to clip out particular sections of DNA in a cell’s nucleus, and replace the removed sections with other DNA segments, presumably replacing “defective” DNA with “good” DNA.
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) were first described in 2012, and the technique was used in human cells in 2013. Earlier this year, Chinese scientists reported using CRISPR in human embryos, and also reported a number of problems with the process. Only a fraction of the 86 embryos used in the experiment showed successful alteration of their DNA. In addition, a number of “off-target” mutations was found — deleterious changes in the DNA that seemed to be caused by the intervention of CRISPR.
Who decides what we do with it?
Representatives from Sangamo BioSciences and Alliance for Regenerative Medicine, along with a philosophy graduate student, authored a comment in Nature earlier this year, stating:
In our view, genome editing in human embryos using current technologies could have unpredictable effects on future generations. This makes it dangerous and ethically unacceptable. Such research could be exploited for non-therapeutic modifications. We are concerned that a public outcry about such an ethical breach could hinder a promising area of therapeutic development, namely making genetic changes that cannot be inherited.
They recommended an international dialogue, with a clear distinction to be made between using this technology for somatic (non-reproductive) cells and using it to make changes that would affect all subsequent generations (that is, germ cell — sperm or egg — modifications).
The International Summit on Human Gene Editing is to be held December 1-3 in Washington, D.C. It is a cooperative effort between the Chinese Academy of Sciences, the Royal Society of Great Britain, and the United States’ National Academy of Sciences and the National Academy of Medicine.
Jennifer Doudna, one of the inventors of Crispr-Cas9, called the summit “this generation’s version of Asilomar” in reference to a meeting in 1975 when the discussion was guidelines for the use of recombinant DNA. One of the conveners of that 1975 meeting was Paul Berg. In an interview with Larry Goldstein, Berg stated, “We made some decisions that were smart in retrospect. For example, one of the things we did not do — and did not include in any way in the agenda — was the ethics.”
Marcy Darnovsky, of the Center for Genetics and Society, is one of the speakers at this year’s summit on human gene editing. According to The Guardian, “Darnovsky wants a total ban on editing human embryos that are destined to become people.” She said:
We would be well on the way to a world in which people who could afford to do so would attempt to give their children the best start in life, and competitive and commercial pressures would kick in. We’d end up in a world of genetic haves and have-nots, and risk introducing new kinds of inequality when we already have shamefully way too much.
We can hope and pray that “this generation’s version of Asilomar” will consider voices besides those of the scientific choir.
