Characterization of APC exon 15 germ-line mutation in FAP family with severe phenotype showing extracolonic symptoms

The adenomatous polyposis coli (APC) gene plays a crucial role in colorectal carcinogenesis. Germ-line mutations of APC gene give rise to familial adenomatous polyposis coli (FAP) - autosomal dominant syndrome manifesting hundreds to thousands of colorectal polyps, if untreated with malignant progression. We have used the techniques of heteroduplex analysis (HDA), protein truncation test (PTT), single strand conformation polymorphism (SSCP) and DNA sequencing for the identification and detailed positional analysis of mutations in IFAP family with the expressive phenotype characterized by polyposis and extracolonic lesions. Detailed analysis revealed a 5bp deletion in a mutation cluster region (MCR) in exon 15 of APC gene in codon 1308. Two screened members of the FAP family exhibited this novel mutation.