Correction to: Nature, published online 05 December 2018.

In this Letter, Mayuko Kurome and Valeri Zakhartchenko should have been listed as authors, with the affiliation: Institute of Molecular Animal Breeding and Biotechnology, Gene Center, LMU Munich, Munich, Germany. Both authors contributed to this work by providing genetically multi-modified donor pigs (see ‘Author contributions’). The Letter has been corrected online.