Baba S
Second Department of Surgery, Hamamatsu University School of Medicine, Japan.
Nihon Geka Gakkai Zasshi. 1998 Jun;99(6):336-44.
Recent advancement of molecular biology disclose responsible genes of FAP(familial adenomatous polyposis) and HNPCC(hereditary non polyposis colorectal cancer). Gardner Syndrome is now categorized as subtype of FAP. Turcot Syndrome is now known as a heterogeneous disease. Turcot Syndrome caused by APC gene develops medulloblastoma and Turcot Syndrome caused by mismatch repair gene develops glioblastoma. Because of the discovery of APC gene, the presymptomatic diagnosis of asymptomatic gene carriers are now available and preventive surgery can be planned. FAP patients with mutated APC gene between codon 1250 and 1464 shows severe phenotype. It is known that FAP patient whose APC gene mutation locates at codon 1309 develops cancer 10 years earlier in comparison to the rest of the cases. Consequently risky rectal mucosa should be removed in this group of patients. As for HNPCC, presymptomatic diagnosis is still not possible because the penetrance rate has not been estimated yet and some additional responsible genes are expected to be discovered. Replication error, mutator phenotype of mismatch repair gene is useful indicator to predict second primary cancers. When the patient in a HNPCC family develops adenoma with microsatellite mistability, preventive colectomy might be one of the surgical option with the informed consent of the patient.
分子生物学的最新进展揭示了家族性腺瘤性息肉病（FAP）和遗传性非息肉病性结直肠癌（HNPCC）的相关基因。加德纳综合征现在被归类为FAP的亚型。Turcot综合征现在被认为是一种异质性疾病。由APC基因引起的Turcot综合征会发展成髓母细胞瘤，而由错配修复基因引起的Turcot综合征会发展成胶质母细胞瘤。由于APC基因的发现，现在可以对无症状基因携带者进行症状前诊断，并可以规划预防性手术。APC基因在密码子1250至1464之间发生突变的FAP患者表现出严重的表型。已知APC基因突变位于密码子1309的FAP患者比其他病例患癌时间早10年。因此，这组患者应切除有风险的直肠黏膜。至于HNPCC，由于尚未估计其外显率，且预计还会发现一些其他相关基因，所以目前仍无法进行症状前诊断。复制错误，即错配修复基因的突变体表型，是预测第二原发性癌症的有用指标。当HNPCC家族中的患者出现具有微卫星不稳定的腺瘤时，在患者知情同意的情况下，预防性结肠切除术可能是手术选择之一。
