In his presentation to the International Human Genome Editing Summit, He Jiankui said another pregnancy resulting from his gene-editing work was in the early stages, Stat News reports. It adds that He also said his work, which he defended, had been submitted to a scientific journal.
He announced earlier this week that he'd used the CRISPR gene-editing tool to alter the CCR5 genes of two embryos during IVF to make them immune to HIV infection, work that led to the birth of twin girls. The announcement has led to condemnation and investigations.
"For this case, I feel proud. I feel proudest," He said, according to Reuters.
New Scientist adds that eight couples enrolled in the trial, though one dropped out, and that 30 embryos have been created, about 70 percent of which have undergone editing. He announced another pregnancy stemming from the trial, and New Scientist says that the trial has now been put on hold.
Stat News reports that He said in his talk that multiple CRISPR injections were needed to boost editing efficiency, that he did note one off-target edit, and that only some of the cells were edited and one of the edits affected five amino acids, leading to mosaicism and uncertainty that the alteration would disrupt the CCR5 receptor and prevent HIV infection.
Attendees at the conference seemed unimpressed with He's responses to their questions, according to Stat News. "His responses displayed a deeply disturbing naiveté about the issues involved," David Liu from Harvard University and a co-founder of Beam Therapeutics tells it.