The cumulative incidences of total chronic graft-versus-host disease (cGVHD) and severe cGVHD at 6 years following IFN-α therapy were 66.2% (95%CI, 55.5–77.0%) and 10.4% (95%CI, 3.6–17.2%), respectively. Here, IFNA2 is linked to chronic graft versus host disease.