Crispr’s damaging side effects
A revolutionary gene-editing tool that won its developers this year’s Nobel Prize in chemistry can cause unwanted and deeply consequential damage in human cells, a new study has found. Crispr-Cas9 is a scissor-like chemical tool that can cut, edit, and insert tiny stretches of genetic material, such as DNA. For the study, researchers were trying to repair a mutation that can cause hereditary blindness. Using sperm from a human donor, they created 40 embryos and injected a Crispr-Cas9 enzyme into 37 of them to snip out the glitch. The other three embryos served as controls. When a cut is made in DNA, cells try to fix the damage. But in about half the embryos, the genetic alterations left the cells so confused that they gave up trying to repair the cut—which resulted in the jettisoning of entire chromosomes. Study lead author Dieter Egli, from Columbia University, tells The Wall Street Journal that this finding won’t “stop the field” of gene editing. “But we have to ask what to do with these powerful tools, and in which context they are safe and efficacious.”
the virus. Recent research has found that the body’s initial antibody response to the disease diminishes quickly, suggesting antibodies won’t provide lasting immunity. But so-called T-cells—a part of the immune system that attacks infected cells—appear to stick around longer. In a new British study, which hasn’t yet been peer-reviewed, researchers measured T-cell activity in 100 U.K. health-care workers six months after they had tested positive for Covid-19. None had been hospitalized; about half had been asymptomatic. All 100 participants showed “robust T-cell responses,” even those whose antibody count had dropped to an undetectable level. The scale of T-cell response was 50 percent higher in people who had shown symptoms of the disease. That could mean people with asymptomatic cases may not retain as much cellular protection, or may simply be better equipped to fight off the virus without a big immune response. The authors emphasize that the study proves only that the T-cells are active, not that they confer immunity. “Cellular immunity,” lead author Shamez Ladhani tells CNBC.com,
“is a complex but potentially very significant piece of the Covid-19 puzzle.”