The objectives of this study are two fold: (1) study of the culture characteristics (cytological, chromosomal and metabolic) of normal, precancerous cells derived from individuals at risk for two heritable cancers of the colorectum, the Gardner syndrome and familial polyposis of the colon. (2) establishment of epithelial cultures from colon derived from both normals and patients with the Gardner syndrome. The goals of these two areas are: (1) If a cell marker indicating the presence of the gene for either of these autosomal dominant disorders can be reliably and reproducibly detected in the cultured cell, then cell culture studies on families at risk would be possible for identification of family members who inherited the mutated gene. (2). The need for colonic epithelium in long term culture is needed to study the influence of environmental factors on epithelium from normals and individuals with mutated genes which appear to make them prone to neoplastic colonic growths.