On Monday, geneticists were just converging on Hong Kong for a long-planned meeting to discuss the future of gene editing. But before many had even collected their name tags, it seemed the future had already arrived.
Chinese scientist He Jiankui of Shenzhen Harmonicare Women's and Children's Hospital revealed that he had edited the DNA in a pair of human embryos, disabling a gene required for HIV infection to take hold. Then his team transferred the embryos into their mother's uterus.
The experiment had resulted in the birth of twin girls, He said.
Trained at Rice and Stanford universities, He offered no independent confirmation or peer-reviewed scientific article to support his claim. If it is true, the twins would represent the world's first genetically edited babies.
The ethical debate over "designer babies" has focused on using gene-editing to select such traits as eye color, intelligence or athletic prowess. But He focused on another trait that is highly prized in China: resistance to HIV.
He had recruited seven couples in which the prospective father was HIV-positive and the mother was not. The couples were offered free fertility treatments and the chance to have a gene called CCR5 disabled in their embryos. The edit was made when the woman's eggs were fertilized with her husband's sperm in a laboratory dish.
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Of 22 embryos created, 16 got the experimental treatment. Eleven of those embryos were implanted into six women before the twin pregnancy was achieved, He told The Associated Press.
News of He's experiment set geneticists abuzz at a time of vigorous debate over when, where and for what gene-editing should be used in humans.
Last year, scientists at Oregon Health & Science University reported the use of gene-editing techniques to rid embryos of familial hypertrophic cardiomyopathy, a heart disorder that can cause premature death. Critics grumbled that editing embryonic DNA was overkill when safer means of preventing the hereditary disorder already exist. In any event, the gene-edited embryos were never implanted in a woman's uterus.
Soon after, a panel of the American Society of Human Genetics and members of 10 organizations from across the globe recommended against genome editing that culminates in human pregnancy until such techniques were studied and debated further.