POLYCLONAL ORIGIN OF COLONIC ADENOMAS IN AN XO XY PATIENT WITH FAP/

It is widely accepted that tumors are monoclonal in origin, arising fr om a mutation or series of mutations in a single cell and its descenda nts. The clonal origin of colonic adenomas and uninvolved intestinal m ucosa from an XO/XY mosaic individual with familial adenomatous polypo sis (FAP) was examined directly by in situ hybridization with Y chromo some probes. In this patient, the crypts of the small and large intest ine were clonal, but at least 76 percent of the microadenomas were pol yclonal in origin.