Paper on 1st use of CRISPR in normal human embryos: problems remain

The first report of the use of CRISPR gene editing in normal human embryos was published today as a short paper from a team in China. There have been rumors for over a year that more CRISPR human embryo papers were coming including some using normal embryos. Here’s one and we can now expect more even as there remain scientific and ethical discussions about this kind of work.

CRISPR human embryo Tang et al

Figure 1b, Tang, et al. CRISPR of 3PN embryos.

You can read the actual paper Tang, et al. here, published in the journal Molecular Genetics & Genomics. This work was published by Jianqiao Liu’s lab. They attempted editing in both abnormal (3PN)  and normal human embryos. Figure 1b from the paper of CRISPR’d nonviable embryos, is shown above.

Some proper gene editing was reportedly evident after injection of CRISPR in normal human zygotes. Further, the efficiency of the genetic modification of the CRISPR’d embryos was higher in the context of using healthy embryos than in previous reports that used nonviable embryos and in the nonviable embryos used in this same study.

But major problems remained such as incorrect editing (making of a disruptive Indel rather than a correction) and quite a bit of mosaicism. While they did not detect off-target effects at a handful of specific predicted possible off-target sites or by some WGS, such sites could still exist. Continue reading