Among all alloSCT patients and among patients receiving an HLA-mismatched graft, patients with severe aGvHD or extended chronic GvHD (cGvHD) show a significantly lower ratio of CD94/NKG2C to CD94/NKG2A during the whole observation period post-alloSCT compared to patients with no or only mild acute or chronic GvHD. The gene discussed is KLRD1; the disease is chronic graft versus host disease.