CD1d is a (glyco)lipid Ag-presenting molecule frequently expressed by malignant cells of myelomonocytic and B cell lineage origin and some solid malignancies (e.g., renal cell carcinoma, medulloblastoma, and glioma), and may promote tumor growth via the presentation of (low-affinity) lipid Ags causing immunosuppressive cytokine release by type 1 NKT cells and engagement of protumoral diverse NKT cells.10 The gene discussed is CD1D; the disease is hereditary clear cell renal cell carcinoma.