Searching for CDH1 gene mutations in early-onset diffuse gastric cancer in Chinese patients.

Abstract

23 Background: CDH1 germline mutations are found to be associated with the development of hereditary diffuse gastric cancer (HDGC) and the early-onset diffuse gastric cancer (EODGC). But the impact of CDH1 gene mutations and large deletions on HDGC and EODGC has not been fully determined in Asians. Although the incidence of gastric cancer is relatively high in China, the detection rate of CDH1 germline mutations in Chinese patients with EODGC is rare compared to that in European patients. Methods: We investigated the mutation status of the CDH1 gene in 57 Chinese EODGC patients younger than 40 years old who met the clinical criteria for HDGC. Polymerase chain reaction-direct sequencing was performed, and multiplex ligation-dependent probe amplification (MLPA) was used to evaluate the patients with negative sequencing results. Associations between mutation, clinicopathologic, and overall survival data were analyzed by SPSS 19. Results: The germline mutations of CDH1gene were identified in 51 (89.5%) of the 57 EODGC patients. The nonsense mutation in exon 13 (c.2200T>C, p.Ala692*) occurred in fourty-six EODGC patients. The missense mutations were detected in twenty patients (Eighteen in exon 5: c.778G>C, p.Glu218Asp; Two in exon 12: c.2012C>G, p.Leu630Val). No deletion or duplication in any patient. Most of the patients carrying the CDH1 mutation in exon 13 had lymph node metastasis when compared with patients lacking CDH1 mutation (87.2% vs 60.0%) ( P < 0.05 ). EODGC patients, lacking germline CDH1 alterations, showed a longer median overall survival (mOS) than patients carrying CDH1 mutation in exon 13 ( P < 0.05 ). Moreover, the presence of CDH1 mutation in exon 13 was associated with the incidence of neural invasion ( P < 0.05 ). Conclusions: This study reveals novel CDH1 mutations in Chinese EODGC patients which had been poorly investigated. The presence of CDH1 mutation in EODGC patients may result in lymph node metastasis and poor prognosis. More research is needed to determine additional genetic targets that trigger EODGC.