Ipilimumab is a human monoclonal antibody (IgG1) that blocks the interaction of CTLA-4 with its ligands and recent phase III clinical trials in patients with unresectable metastatic melanoma showed overall survival benefit with ipilimumab treatment compared to gp100 vaccination or dacarbazine monotherapy [8, 9]. The gene discussed is PMEL; the disease is metastatic melanoma.