Identification of a novel duplication in the APC gene using multiple ligation probe amplification in a patient with familial adenomatous polyposis.
Germline mutations in the adenomatous polyposis coli (APC) gene cause familial adenomatous polyposis (FAP), an autosomal dominant disease characterized by hundreds to thousands of adenomatous polyps in the colon and rectum, with progression to colorectal cancer. The majority of APC mutations are nucleotide substitutions and frameshift mutations that result in truncated proteins. Recently, large genomic alterations of the APC gene have been reported in FAP. DNA from 15 FAP patients, in whom no APC germline mutations were detected with denaturing high performance liquid chromatography, was analyzed with multiplex ligation-dependent probe amplification (MLPA) to evaluate gross genomic alterations in the APC gene. In one case, MLPA identified a novel duplication of exons 2-6 in one copy of the APC gene. Reverse transcriptase-polymerase chain reaction revealed that the mutant allele contained an in-frame multiexon duplication including 18 nucleotides located in exon 2, upstream of the ATG initiation codon. The presence of a premature stop codon in the duplicated sequence leads to the synthesis of a truncated APC polypeptide. These findings highlight the utility of evaluating infrequent APC mutation events in FAP patients using MLPA.
Pedace
Lucia
L
Medical Genetics, Experimental Medicine Department, University of Rome La Sapienza, S. Camillo-Forlanini Hospital, Circ. ne Gianicolense n. 87, 00152 Rome, Italy.
Majore
Silvia
S
Megiorni
Francesca
F
Binni
Francesco
F
De Bernardo
Carmelilia
C
Antigoni
Ivana
I
Preziosi
Nicoletta
N
Mazzilli
Maria Cristina
MC
Grammatico
Paola
P
D011125:Adenomatous Polyposis Coli / Q000235:genetics*; D015153:Blotting, Western; D018389:Codon, Nonsense; D018388:Codon, Terminator / Q000235:genetics; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000235:genetics*; D005091:Exons; D005260:Female; D020440:Gene Duplication; D017491:Genes, APC; D018095:Germ-Line Mutation / Q000235:genetics*; D006801:Humans; D008297:Male; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018389:Codon, Nonsense; D018388:Codon, Terminator; D012333:RNA, Messenger