Author:
Liang Dan,Gutierrez Nuria Marti,Chen Tailai,Lee Yeonmi,Park Sang-Wook,Ma Hong,Koski Amy,Ahmed Riffat,Darby Hayley,Li Ying,Dyken Crystal Van,Mikhalchenko Aleksei,Gonmanee Thanasup,Hayama Tomonari,Zhao Han,Wu Keliang,Zhang Jingye,Hou Zhenzhen,Park Jumi,Kim Chong-Jai,Gong Jianhui,Yuan Yilin,Gu Ying,Shen Yue,Olson Susan B.,Yang Hui,Battaglia David,O’Leary Thomas,Krieg Sacha A.,Lee David M.,Wu Diana H.,Duell P. Barton,Kaul Sanjiv,Kim Jin-Soo,Heitner Stephen B.,Kang Eunju,Chen Zi-Jiang,Amato Paula,Mitalipov Shoukhrat
Abstract
AbstractApplications of genome editing ultimately depend on DNA repair triggered by targeted double-strand breaks (DSBs). However, repair mechanisms in human cells remain poorly understood and vary across different cell types. Here we report that DSBs selectively induced on a mutant allele in heterozygous human embryos are repaired by gene conversion using an intact wildtype homolog as a template in up to 40% of targeted embryos. We also show that targeting of homozygous loci facilitates an interplay of non-homologous end joining (NHEJ) and gene conversion and results in embryos which carry identical indel mutations on both loci. Additionally, conversion tracks may expand bidirectionally well beyond the target region leading to an extensive loss of heterozygosity (LOH). Our study demonstrates that gene conversion and NHEJ are two major DNA DSB repair mechanisms in preimplantation human embryos. While gene conversion could be applicable for gene correction, extensive LOH presents a serious safety concern.
Publisher
Cold Spring Harbor Laboratory