Dr. He Jiankui presented data that a set of genetically altered twin girls (Lulu and Nana), conceived through in vitro fertilization and at which time the crispr-cas9 gene editing platform was implanted in the egg, were born. Justifying his genetic experiments ethically by explaining a thorough informed consent process and using the vision for HIV disease prevention as his reason, he was able to remove the CCR5 receptor (see our last 2 blog posts describing this molecule and its importance in HIV acquisition) from both alleles of one of the girl’s genome (the other twin only had one allele removed from her genome). The donor sperm came from an HIV positive father and the egg was from an HIV negative mother. Using “3rd world countries” as his ethical motivation, he sees this technology as able to confer HIV resistance to a couple who are concerned that a potential pregnancy could transfer HIV to the baby.
He presented his research at the 2nd International Summit on Human Genome Editing this week in Hong Kong which seemed thorough and thoughtful, proceeding over 3-4 years from mice to monkeys to embryos for “safety testing” (making sure that the crispr -cas9 would recognize the right gene and not “clip out” an unrelated gene or remove a big chunk of dna that would affect neighboring genes) to human trials involving 7 couples, one of which conceived and bore forth Lulu and Nana in genetically altered form. He claims the twins are healthy.
He has presented his data for peer review publication. In addition he took questions from the scientific community at the conference who remained civil, but raised many ethical concerns not the least of which is that there are safer ways to prevent the vertical transmission (mother to baby) of HIV.
See the attached link below for the article and embedded video of his presentation at the conference. His presentation starts at video time 1:18.00, he has a nice cartoon outlining his experiments at time 1:32.50 and the q and a starts at 1:39.00.
He chose the CCR5 single gene as the target for the first embryonic genome editing experiment because “it is already well studied and has shown therapeutic potential in HIV”.
This technology has immense potential for treating many types of disease but has the potential to cause severe injury through gene mutation or other unforeseen problems (both enhancing and hurting) in someone with a successfully altered genome. There is also the concern for progressing beyond the medical use to the “designer” use for human genome editing.