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A12 SCIENCE
Friday 30 OctOber 2020
Lab tests show risks of using CRISPR gene editing on embryos

By MARILYNN MARCHIONE Previous researchers who
AP Chief Medical Writer thought they had repaired
A lab experiment aimed at a defect in embryos may
fixing defective DNA in hu- have been misled into
man embryos shows what thinking they had suc-
can go wrong with this ceeded because usual lab
type of gene editing and tests no longer detected
why leading scientists say the mutation. However,
it's too unsafe to try. In more more extensive testing like
than half of the cases, the what was done in this study
editing caused unintended shows that other changes
changes, such as loss of an could have happened,
entire chromosome or big such as an entire chromo-
chunks of it. some being wiped out, Egli
Columbia University re- said. The new work suggests
searchers describe their that gene editing might
work Thursday in the jour- hold promise for correcting
nal Cell. They used CRISPR- disorders caused by an ex-
cas9, the same chemical tra copy of a chromosome,
tool that a Chinese scientist such as Down syndrome.
used on embryos in 2018 to However, the danger re-
help make the world's first vealed in the new study
gene-edited babies, which "further affirms we are not
landed him in prison and In this Oct. 9, 2018, file photo, a lab dish containing embryos that have been injected with Cas9 ready, not even close" to
drew international scorn. protein and PCSK9 sgRNA is seen in a laboratory in Shenzhen in southern China's Guangdong try this, Dr. Eric Topol wrote
province.
The tool lets scientists cut Associated Press in an email.
DNA in a precise spot and "This takes the concerns
has profound potential for that have already been
good — it's already used harm. ness. Editing was aimed at any of the cells from em- expressed about human
to raise better crops and "If our results had been adding the missing letter so bryos edited at fertilization. embryo editing to another
livestock, holds promise known two years ago, I the gene would work. It only worked in three of level," added Topol, who
for treating diseases and doubt that anyone would In some embryos, the edit- the 45 cells from embryos heads the Scripps Research
earned its discoverers a No- have gone ahead" and ing was tried at fertilization, edited at the later stage. Translational Institute in San
bel Prize earlier this month. tried it on embryos intend- thought to be the best time In many of the rest, "what Diego and had no role in
But using it on embryos, ed for pregnancy, said bi- for such attempts. Other we found is that instead of the new work.
sperm or eggs makes ologist Dieter Egli, who led embryos were edited when the mutation being fixed, In the U.S., federal funds
changes that can pass to the study. they contained two cells the chromosome carrying can't be used for research
future generations. Several Researchers made 40 and were almost two days the mutation is gone" — on human embryos, so
international panels of sci- embryos with eggs from old. Cells then were ana- a profound change that the Columbia researchers
entists and ethicists have healthy donors and sperm lyzed at various stages of likely dooms the embryo, used private money from
said it's too soon to know from a man with a gene development to see how Egli said. Many other cells two foundations. Several
whether that can be done mutation -- a single letter many had the mutation re- showed changes in other of the scientists have ties
safely, and the new Colum- missing in the DNA alpha- paired. chromosomes that also to gene therapy or analysis
bia work shows the possible bet -- that causes blind- Surprisingly, it didn't work in could do harm. companies.q

How does the coronavirus affect the heart?

By The Associated Press versity of Chicago says One small study found evi-
How does COVID-19 affect people with heart disease dence of the virus in the
the heart? are most at risk for virus- hearts of COVID-19 patients
Even though it's known as related damage to the who died from pneumonia.
a respiratory virus, doc- heart. But heart complica- Another, using heart imag-
tors believe the coronavi- tions also have been found ing, found inflammation
rus can directly infect the in COVID-19 patients with of the heart muscle in four
heart muscle and cause no known previous disease. college athletes who had
other problems leading to A recent review in the Jour- recovered from mild COV-
heart damage. nal of the American Col- ID-19 infections. There were
In some people, as COV- lege of Cardiology notes no images available from
ID-19 decreases lung func- that evidence of heart in- before the athletes got
tion, it may deprive the volvement has been found sick, and therefore no way
heart of adequate oxygen. in at least 25% of hospital- to know if they had pre-ex-
Sometimes it causes an A health worker makes a heart sign while she and her fellow ized coronavirus patients. isting heart problems.
overwhelming inflamma- workers celebrate as the last three patients are released from At some centers, the rate Dr. Tom Maddox, an Ameri-
tory reaction that taxes the a field hospital at the National Stadium Mane Garrincha, after is 30% or higher. And some can College of Cardiology
heart as the body tries to recuperating from COVID-19, in Brasilia, Brazil, Thursday, Oct. studies have found elevat- board member, says it's un-
fight off the infection. 15, 2020. ed enzyme levels and oth- clear if the virus can cause
The virus can also invade Associated Press er signs suggesting heart a normal heart to become
blood vessels or cause in- Clots throughout the body blood thinners, although damage even in patients dysfunctional.
flammation within them, have been found in many there is no consensus on with milder disease. It is not "There's still so much we
leading to blood clots that COVID-19 patients. That that treatment. known whether that dam- don't know," Maddox
can cause heart attacks. has led some doctors to try Dr. Sean Pinney of the Uni- age is permanent. said.q