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Designer babies highly unlikely….
Link: https://www.nytimes.com/2017/08/04/science/gene-editing-embryos-designer-babies.html
Gene Editing for ‘Designer Babies’?
Highly Unlikely, Scientists Say
Fears that embryo modification could allow parents to custom
order a baby with Lin-Manuel Miranda’s imagination or
Usain Bolt’s speed are closer to science fiction than science.By PAM BELLUCKAUG. 4, 2017
Now that science is a big step closer to being able to fiddle with the genes of a human embryo, is it time to panic? Could embryo editing spiral out of control, allowing parents to custom-order a baby with Lin-Manuel Miranda’s imagination or Usain Bolt’s speed?
News that an international team of scientists in Oregon had successfully modified the DNA of human embryos has renewed apprehensions that babies will one day be “designed.” But there are good reasons to think that these fears are closer to science fiction than they are to science.
Here is what the researchers did: repair a single gene mutation on a single gene, a defect known to cause — by its lonesome — a serious, sometimes fatal, heart disease.
Here is what science is highly unlikely to be able to do: genetically predestine a child’s Ivy League acceptance letter, front-load a kid with Stephen Colbert’s one-liners, or bake Beyonce’s vocal range into a baby.
That’s because none of those talents arise from a single gene mutation, or even from an easily identifiable number of genes. Most human traits are nowhere near that simple.
“Right now, we know nothing about genetic enhancement,” said Hank Greely, director of the Center for Law and the Biosciences at Stanford. “We’re never going to be able to say, honestly, ‘This embryo looks like a 1550 on the two-part SAT.’”
Even with an apparently straightforward physical characteristic like height, genetic manipulation would be a tall order. Some scientists estimate height is influenced by as many as 93,000 genetic variations. A recent study identified 697 of them.
Can Gene Editing Actually Do That?
A new technique known as Crispr has revolutionized humans’ ability to edit DNA. See if you can identify whether a given development has already happened, could eventually happen or is pure fiction.“You might be able to do it with something like eye color,” said Robin Lovell-Badge, a professor of genetics and embryology at the Francis Crick Institute in London.
But “if people are worried about designer babies, they’re normally thinking of doing special — different things than the normal genetic stuff.”
The gene-modification process used in the new study also turns out to be somewhat restrictive. After researchers snipped the harmful mutation from the male gene, it copied the healthy sequence from that spot on the female gene.
That was a surprise to the scientists, who had inserted a DNA template into the embryo, expecting the gene to copy that sequence into the snipped spot, as occurs with gene editing in other body cells. But the embryonic genome ignored that template, suggesting that to repair a mutation on one parent’s gene in an embryo, a healthy DNA sequence from the other parent is required.
“If you can’t introduce a template, then you can’t do anything wild,” Dr. Lovell-Badge said. “This doesn’t really help you make designer babies.”
Talents and traits aren’t the only thing that are genetically complex. So are most physical diseases and psychiatric disorders. The genetic message is not carried in a 140-character tweet — it resembles a shelf full of books with chapters, subsections and footnotes.
So embryonic editing is unlikely to prevent most medical problems.
But about 10,000 medical conditions are linked to specific mutations, including Huntington’s disease, cancers caused by BRCA genes, Tay-Sachs disease, cystic fibrosis, sickle cell anemia, and some cases of early-onset Alzheimer’s. Repairing the responsible mutations in theory could eradicate these diseases from the so-called germline, the genetic material passed from one generation to the next. No future family members would inherit them.
A composite image showing the development of embryos after injection of a gene-correcting enzyme and sperm from a donor with a genetic mutation known to cause hypertrophic cardiomyopathy. Credit Oregon Health & Science University
But testing editing approaches on each mutation will require scientists to find the right genetic signpost, often an RNA molecule, to guide the gene-snipping tool.In the study reported this week, it took 10 tries to find the right RNA, said Juan Carlos Izpisua Belmonte, a co-author and geneticist at the Salk Institute.
Dr. Greely noted that while scientists work to get human embryonic editing ready for clinical trials (currently illegal in the United States and many countries), alternate medical treatments for these diseases might be developed. They may be simpler and cheaper.
“How good one technique is depends on how good the alternatives are, and there may be alternatives,” he said.
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