A Novel Germline Mutation in Exon 15 of the APC Gene in Attenuated Familial Adenomatous Polyposis: A Report of Two Cases
A 23-year-old man with no previous medical history and incidentally discovered multiple gastric polyps was referred to Gangnam Severance Hospital. The patient had gastric tubular adenoma with dysplasia in the antrum of the stomach. Endoscopic submucosal dissection (ESD) was performed for the gastric adenoma in the antrum, and multiple biopsies were done for the variable sized polyps in the upper body and fundus (). Final pathologic report showed tubular adenoma with low grade dysplasia for the antral lesion (). Polyps in the upper body and fundus were confirmed as fundic gland polyps. Suspected of having polyposis, the patient underwent colonoscopy which showed fewer than 100 colorectal polyps of 3 to 5 mm size from hepatic flexure to the rectum. The colorectal polyps confirmed as tubular adenoma with low grade dysplasia on pathologic report (). Colonic polyps close or equal to 5 mm in size were endoscopically removed using polypectomy snare. Genetic analysis using polymerase chain reaction (PCR) denaturing high performance liquid chromatography and direct sequencing revealed a novel frameshift mutation in the exon 15 of the APC gene. Deletion of adenine-guanine (AG) and insertion of thymine (T) in codon 3833-3834 resulted in the formation of stop codon 1287 (c.3833-3834delAGinsT) (, ).