6]Protein truncation test for presymptomatic diagnosis of familial adenomatous polyposis

Abstract

Publisher Summary The chapter presents a study on the protein truncation test for presymptomatic diagnosis of familial adenomatous polyposis. The protein truncation test (PTT), also known as the “ in vitro -synthesized protein (IVSP) assay,” is a method of direct mutation detection that is based on the in vitro transcription and translation of polymerase chain reaction (PCR)-amplified sequences. The PTT allows the selective detection of chain-terminating mutations in large amplified segments and has been shown to be uniquely useful for the molecular diagnosis of familial adenomatous polyposis (FAP). Familial adenomatous polyposis is an autosomal dominant predisposition to colorectal cancer, characterized by the development of numerous adenomatous polyps located in the colorectum. Germ line mutations of this gene, designated as “adenomatous polyposis coli” (APC), have been identified in individuals affected with FAP, while somatic APC mutations have been found in sporadic colorectal cancers. Because of the distribution and nature of the mutations in the large APC gene, an ideal method for mutation analysis would be to allow the selective detection of chain-terminating mutations in large stretches of the coding sequence. Such a method, called the “protein truncation test” (PTT), has been developed for the detection of point mutations in the Duchenne muscular dystrophy ( DMD ) gene. The PTT allows the rapid detection of translation-terminating mutations in the DMD gene, which has a coding region of about 12 kb dispersed among 79 exons.