A Chinese scientist says he has edited the DNA of twin baby girls so that they can’t get a disease. If true, the news is an important and worrying change from the way scientists usually work with DNA.
DNA is a tiny collection of information and instructions stored in a chemical form. Just like computer code tells a computer what to do, DNA tells cells, the building blocks of the body, what to do. Every living thing has DNA that causes it to grow in a certain way.
Small bits of DNA, called “genes”, work to control different parts of how a living thing grows. For example, humans have genes that control eye color; other genes might control whether someone’s hair is curly or not. Children get their genes from both of their parents.
Humans have around 20,000 genes. Some work by themselves, others work together. Some may do more than one thing. There is a lot that scientists still do not know about human DNA.
One new way scientists have been studying genes is by “editing” DNA . Scientists have a tool called CRISPR that will let them cut out a piece of DNA, similar to the way you might replace a word when typing on a computer. If they want to, they can replace the gene they cut out with something new.
Using CRISPR, scientists have studied and changed the DNA of plants and animals. They have also worked on human DNA in laboratories.
Now, Chinese scientist He Jiankui says he has created the world’s first “gene-edited” babies by editing the DNA of human eggs that were later placed back in the mother. He said he did it to protect the babies from a disease called HIV.
This news has shocked and worried scientists and others around the world. Scientists weren’t surprised that gene-editing humans was possible. They knew it was. They were shocked because Dr. He ran an unneeded test on human beings.
Editing human DNA this way is not safe. Though CRISPR can edit DNA, it is like a bad pair of scissors. It doesn’t cut exactly what it’s supposed to cut. Dr. He could not be sure his editing would help. In fact, he says it only protected one of the babies from HIV.
Worse, since genes are complicated, changing one can have unexpected effects. For example, Dr. He’s changes may make the girls more likely to get the flu.
A bigger worry is that Dr. He has created a new kind of DNA that won’t just affect these babies. It will also affect any children the girls have when they grow up. Any problems that Dr. He has caused will be passed down and spread among other humans over time.
China says that Dr. He broke the law. But because editing DNA for humans is such a new idea, it’s not clearly covered by laws in many places. Still many scientists say that even if there was no law, what Dr. He did was wrong.
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