Turcot's syndrome evidence for autosomal dominant inheritance

A case of Turcot's syndrome (colonic polyposis plus a malignant central nervous system tumor) occurring in a kindred with autosomal dominant colonic polyposis is presented. It is proposed that Turcot's syndrome patients can be classified into Type I where only siblings are affected and Type II where two or more generations have colonic polyposis. A third nonfamilial group cannot be classified into Type I or II based on available information. Evidence is presented suggesting Turcot's syndrome is best considered an additional phenotype of familial polyposis and is most likely inherited in an autosomal dominant manner.