Donor T cells attack host epithelial tissues in part via the interaction of T cell integrins with E-cadherin (Ecad) expressed on epithelia, which is one of the mechanisms for graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The gene discussed is CDH1; the disease is graft versus host disease.