B Retraction Note: Mammalian Genome (2021) 32:466-475 b https://doi.org/10.1007/s00335-021-09896-y The Editors-in-Chief have retracted this article because the authors have been unable to provide documentary evidence of ethics approval and did not respond to requests to provide the original images and data. Yanhui Mei and Yuhai Wu have contributed equally to this work.