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. This evidence concerns the gene MLH1 and malignant colon neoplasm.