[Molecular and genetic studies for hereditary colon cancer in two patients and their families]

About 30% of cases of colon cancer (CC) have a family history of CC, and only 5% are hereditary forms. Hereditary forms have an increased risk of CC and other tumors.

To report the molecular and genetic study in two families with hereditary CC.

Molecular analysis of the adenomatous polyposis coli (APC) gene of familial adenomatous polyposis (FAP), was done in a patient with multiple benign polyps and his children. Molecular analysis was performed for MLH1 gene mutation of hereditary non-polyposis colon cancer (HNPCC) in an asymptomatic patient with family history of multiple cancers and his mother with a confirmed mutation in the MLH1 gene.

The patient with FAP had an insertion of 17 base pairs in exon 9 of the APC gene and two of his children had the same mutation. The patient with history of HNPCC did not have the family mutation on MLH1.

In the case of FAP, molecular study was performed in his children since manifestations in carriers of the mutation may begin in childhood. If the second patient would have had the mutation, the study of his children could have been postponed until the age of 18, when the risk for CC is increased.