title: An AT-rich region in the APC gene may cause misinterpretation of familial adenomatous polyposis molecular screening.
abstract: Familial adenomatous polyposis (FAP) is an autosomal-dominant condition mainly due to a mutation of the adenomatous polyposis coli (APC) gene. The present study reports evidence of a technical issue occurring during the mutational analysis of APC exon 4. Genetic conventional direct sequence analysis of a repetitive AT-rich region in the splice acceptor site of APC intron 3 could be misinterpreted as a pathogenetic frameshift result. However, this potential bias may be bypassed adopting a method for random mutagenesis of DNA based on the use of a triphosphate nucleoside analogues mixture. Using this method as a second-level analysis, we also demonstrated the nonpathogenic nature of the variant in the poly A trait in APC exon 4 region (c.423-4delA) that do not result in aberrant splicing of APC exons 3-4; conversely, we did not find a previously reported T deletion/insertion polymorphism.
authors.affiliation: Laboratory of Molecular Diagnostics, Department of Laboratory Medicine and Advanced Biotechnologies, IRCCS San Raffaele Pisana, via della Pisana 235, Rome, Italy. raffaele.palmirotta@sanraffaele.it
authors.forename: Raffaele
authors.initials: R
authors.lastname: Palmirotta
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: De Marchis
authors.forename: Giorgia
authors.initials: G
authors.lastname: Ludovici
authors.forename: Barbara
authors.initials: B
authors.lastname: Leone
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Valente
authors.forename: Jhessica
authors.initials: J
authors.lastname: Alessandroni
authors.forename: Antonella
authors.initials: A
authors.lastname: Spila
authors.forename: David
authors.initials: D
authors.lastname: Della-Morte
authors.forename: Fiorella
authors.initials: F
authors.lastname: Guadagni
mesh_terms: D020856:AT Rich Sequence; D011125:Adenomatous Polyposis Coli / Q000175:diagnosis / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D004252:DNA Mutational Analysis / Q000379:methods; D003951:Diagnostic Errors; D005091:Exons; D017491:Genes, APC; D005820:Genetic Testing; D006801:Humans; D025202:Molecular Diagnostic Techniques; D008969:Molecular Sequence Data; D009154:Mutation; D011110:Polymorphism, Genetic; D022821:RNA Splice Sites / Q000235:genetics
chemical_list: D022821:RNA Splice Sites