VH replacement in mouse and human

VH replacement was originally proposed to explain how functional IgH genes can be generated in mouse pre B cell lines harboring non-functional IgH rearrangements. The occurrence of VH replacement has later been demonstrated in different knock-in mouse models with rearranged VDJ genes and in human immature B cells. However, the occurrence and biological significance of VH replacement in non-engineered mouse is still under debating. Moreover, it remains to be investigated how VH replacement is regulated. We would like use this opportunity to update the current advances from different research groups regarding VH replacement in mouse and human.