The observation that before HSCT 2 out of 13 anti-HBc positive patients became HbsAg positive during follow-up, compared to 2 out 157 anti-HBc negative cases, poses the question whether these episodes were true “de novo” rather than reactivation of latent infection, an event already reported in the literature25. This evidence concerns the gene KRT88P and disease arising from reactivation of latent virus.