FAP is an inherited human disease associated with hundreds to thousands of colon polyps and a high incidence of colon cancer, a common malignancy in industrialized countries. As with many other human diseases, colon cancer is polygenic caused by the interaction of several genes that may modify each other's expression. Possible explanations for such variations are the presence of a modifying gene, environmental considerations such as diet, or a combination of factors. Mouse model systems offer a powerful research tool for studying complex interactions related to cancer development.
Modifier genes are far more difficult than other types of genes to locate in mammals.
The next steps will be to sequence the Mom1 gene and identify its human homolog, events which could have important diagnostic implications for human families. Understanding how modifying genes exert their effects on cancer-promoting genes may one day lead researchers to develop new forms of cancer therapy.