There are a number of persuasive arguments for repairing human DNA, including germline DNA, writes Harvard Medical School's George Church in the New England Journal of Medicine.
"As we list compelling reasons to repair human DNA (both soma and germline), we include infirmity of our embryos, infertility in adults, and cognitive decline in our oldest citizens," he writes.
Over the summer, researchers from Oregon State Health and Science University reported in Nature that they'd used the CRISPR/Cas9 gene-editing system to correct in embryos MYBPC3 mutations linked to hypertrophic cardiomyopathy. While some questions have arisen as to whether the researchers fixed the pathogenic allele or merely eliminated the affected copy, the work raised the possibility of gene editing of human embryos.
Church notes that the Oregon team was able to increase the fraction of embryos containing unaffected copies of the gene from 50 percent to 72 percent, though he adds that the closer that figure can get to 100 percent, the better. A number of tweaks could be made to improve the procedure, he adds, such as altering it for use on SNVs and intervening before sperm are formed to reduce risk to embryos, among others.
Still, he writes that some critics are concerned about the ethical ramifications of altering germline DNA, particularly for future generations, but Church argues that "[d]oing nothing merely for fear of unknown risks is itself risky — greatly restricting the advance of medicine."