Pedace Lucia, Majore Silvia, Megiorni Francesca, Binni Francesco, De Bernardo Carmelilia, Antigoni Ivana, Preziosi Nicoletta, Mazzilli Maria Cristina, Grammatico Paola
Medical Genetics, Experimental Medicine Department, University of Rome La Sapienza, S. Camillo-Forlanini Hospital, Circ. ne Gianicolense n. 87, 00152 Rome, Italy.
Cancer Genet Cytogenet. 2008 Apr 15;182(2):130-5. doi: 10.1016/j.cancergencyto.2008.01.009.
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.
腺瘤性息肉病 coli（APC）基因的种系突变会导致家族性腺瘤性息肉病（FAP），这是一种常染色体显性疾病，其特征是结肠和直肠中有数百至数千个腺瘤性息肉，并会发展为结直肠癌。大多数 APC 突变是核苷酸替换和移码突变，会导致蛋白质截短。最近，FAP 中已报道了 APC 基因的大片段基因组改变。对 15 例 FAP 患者的 DNA 进行分析，这些患者通过变性高效液相色谱法未检测到 APC 种系突变，使用多重连接依赖探针扩增（MLPA）来评估 APC 基因中的总体基因组改变。在一个病例中，MLPA 在一个 APC 基因拷贝中鉴定出了外显子 2 - 6 的新重复。逆转录酶 - 聚合酶链反应显示，突变等位基因包含一个框内多外显子重复，其中包括位于 ATG 起始密码子上游外显子 2 中的 18 个核苷酸。重复序列中存在提前终止密码子会导致截短的 APC 多肽合成。这些发现突出了使用 MLPA 评估 FAP 患者中罕见的 APC 突变事件的实用性。
