Maybe it is difficult to extrapolate from mouse to human embryonic stem cells but one observed event is not even listed here.
The -15 genotype has a probability of less than 0.05%. For +1 genotype the probability is 0.09% and for the -4 deletion it is 3.74%.
Looking therefore again at the Hong Kong slides of He Jiankui, I am getting doubts if the chromatogram of embryo 2 is correct interpreted even if we admit that the labels of embryo 1 and 2 have been switched..
Embryo 2 does not show a clean sequence at all and certainly not a -4/+1 genotype as indicated. The sequence “ATTTTCCATACAG-ATTCAATTCTGGACTAAAATAAATACCT” isn’t even a human sequence at all.