Turcot syndrome is the association of colorectal polyposis with primary 
neuroepithelial tumors of the central nervous system such as glioblastoma and 
medulloblastoma. Including putative patients, more than 150 familial or sporadic 
cases of the syndrome have been reported in literature. Since early reports, 
there is considerable controversy regarding the modality of genetic transmission 
and the distinction from other syndromes like familial adenomatous 
polyposis(FAP). Recent molecular evidence suggests that Turcot syndrome could be 
divided into the following two entities based on the distinct genetic 
backgrounds. (1) True Turcot syndrome(autosomal recessive): Intestinal polyps 
are less in number(< 100), large in size and apt to transform to the malignant 
tumor. Brain tumor is mainly diagnosed as glioblastoma or astrocytoma and 
mismatch repair genes might be involved. (2) FAP-associated type(autosomal 
dominant): Predisposing to medulloblastoma.