The Turcot syndrome (TS) is a rare, probably autosomal recessive, disorder 
characterized by development of primary neuroepithelial tumors of the central 
nervous system (CNS) and numerous adenomatous colorectal polyps. To examine the 
possible involvement of mutations of the APC gene, which is responsible for 
familial adenomatous polyposis (FAP), in Turcot syndrome, we examined DNAs from 
TS patients for alterations in this gene by means of ribonuclease protection 
analysis. Germ-line APC mutations were detected in each of three unrelated cases 
of TS, and additional (somatic) mutations were observed in colonic adenomas that 
had developed in one of these patients. However, no somatic mutations in APC 
were found among 91 neuroepithelial tumors (medulloblastoma, glioblastoma, 
astrocytoma, and oligodendroglioma), whether sporadic or associated with TS. 
These results suggest that the APC gene is associated with pathogenesis of one 
feature of TS, but that at least one other gene is responsible for the genesis 
of neuroepithelial tumors in the CNS.