Genome Engineering Using Haploid Embryonic Stem Cells.

Haploidy is a useful feature for the study of gene function because disruption of one allele in haploid cells, which contain only a single set of chromosomes, can cause loss-of-function phenotypes. Recent success in generating haploid embryonic stem (ES) cells from several mammalian species, including human, provides a new platform for simple genetic manipulation of the mammalian genome. The genome-editing potential of the CRISPR/Cas system is enhanced by the use of haploid ES cells. For example, CRISPR/Cas has been used for high-efficiency generation of multiple knockouts and knockins in haploid ES cells, with potential application in genome-wide screening. In addition, live mice can be successfully obtained by nuclear transplantation of haploid ES cells into oocytes, providing a novel approach for the generation of gene-modified animals.