[Cytogenetic and medical genetic research on families with a high predisposition for the development of cancer of the gastrointestinal tract].

Three families suspected of predisposition to tumor development in the gastrointestinal tract have been followed in a medico- and cytogenetical study. According to genealogical analysis, cancer predisposition was confirmed in one family only. However, both specific and non-specific signs of genome instability and possible malignant transformation of cells were identified in members of the other two families.