Dear Editor: Familial adenomatous polyposis (FAP) is characterized by multiple intestinal adenomatous polyps, congenital hypertrophic retinal pigment epithelial (CHRPE) lesions, epidermoid cysts, and osteomas on the mandible. If left untreated, one or more of these colorectal polyps will progress to colorectal cancer typically by the age of 40 years with consequent need for prophylactic surgery. Cases with accompanying thyroid carcinoma had been reported with only 1–2% of patients with a history of FAP and are found mostly in young women aged 30 or below at the time of diagnosis. We present a case with hereditary colorectal carcinoma due to a history of FAP and papillary thyroid carcinoma with no hereditary mutation observed in the analyses of APC, TP53, BRCA1, and BRCA2 genes. A 34-year-old woman was admitted complaining of dyspepsia and constipation. Her physical examination revealed tenderness and a palpable mass in the left pelvic area. In her past medical history, she was diagnosed with papillary thyroid carcinoma, underwent a total thyroidectomy with central compartment of neck node dissection in 1996, and was still in remission. In pelvic ultrasound examination a huge tumor (15.3×10.7 cm) was reported; pelvic magnetic resonance imaging also revealed a large tumor (17.0×13.0×9.0 cm) in the left parametrium. Results for tumor markers (CEA, CA 19-9, CA 15-3, and CA 125) were unremarkable. She was subjected to pelvic exploration with a diagnosis of an ovarian tumor. Exploration showed an infiltrating tumor in the left ovary originated from the rectosigmoid junction. Further exploration showed that there was a synchronous tumoral mass in the left colon and polyposis coli throughout the entire colon. Subtotal colectomy with Hartman pouch was performed, and the pathology was reported as polyposis coli with undifferentiated adenocarcinoma of the colon in two localizations, which infiltrated to the ovary and tuba uterine. After the surgical examination, adjuvant chemotherapy was planned. In her detailed pedigree analyses, a history of FAP was observed in her father and one of her uncles. The patient and her brother had no routine colonoscopy analyses. Different molecular analyses were performed on the candidate genes to find the hereditary gene mutations in this family. The DNA was isolated from peripheral blood of the patient by using standard protocol; mutation analyses of APC gene (exons 1 to 15) were amplified. Exons 5–9 of the p53 gene were amplified using primers designated from the published sequence. PCR was performed according to standard methods. The common mutations of BRCA1 and BRCA2 genes (2312del5, 2800delAA, 3166ins5, G. Yagci (*) Department of Surgery, Gulhane Military Medical Academy, Etlik, 06018 Ankara, Turkey e-mail: gyagci@gata.edu.tr Tel.: +90-312-3045113 Fax: +90-312-3045002