It is reasonable to suspect Lynch syndrome in any patient who develops melanoma in the context of the cancers arising from defects in the mismatch repair enzymes MLH1, MSH2, EPCAM, MSH6, and PMS2, including colon cancer and cancers of the endometrium, small intestine, ureter/uterus, or renal pelvis. The gene discussed is PMS2; the disease is malignant colon neoplasm.