Detection of CDH1 gene variants in early-onset diffuse gastric cancer in Chinese patients

The type and frequency of E-cadherin (CDH1) germline variants in China for the early-onset diffuse gastric cancer (EODGC) has not been well established. Our study tend to screen and characterize germline variants for CDH1 gene in EODGC patients and in general population in China.

Peripheral blood samples were collected from 57 EODGC patients (age ≤ 40 years) who underwent resection surgery for primary gastric cancer. DNA was extracted from peripheral blood leucocytes and polymerase chain reaction amplification (PCR) was performed to amplify and sequence the CDH1 gene. Statistical analysis was performed using the SPSS 19 software.

CDH1 genetic screening results: 2 missense in exon 5 (c.778G > C, 26.3%) and 12 (c.2012C > G, 1.8%), and 1 synonymous (c.2200T > C, 72.8%) in exon 13. According to the c.2200T > C variant, the CDH1 C frequency was 62.3% and the T frequency 37.7%, while the CC homozygote frequency was 43.9%, the TT homozygote 19.3% and the CT heterozygote 36.8%. According to the c.778G > C variant, the CDH1 C frequency was 15.8% and the G frequency 84.2%, while the GG homozygote frequency was 68.4%, the GC heterozygote 31.6%. When comes to the c.2012C > G variant, the CDH1 C frequency was 98.2% and the G frequency 1.8%, while the CC homozygote frequency was 96.5%, the GC heterozygote 3.5%. Statistical association was analyzed among the EODGC patients and BDs group tested for the three variants. Lymph node metastasis rate was found to be significantly higher in patients with c.2200T > C (P = 0.04). The difference in OS with or without c.2200T > C variant was found to be sig- nificant (P < 0.05).

No deletions or insertions were found in the CDH1 exon boundaries. All of the variants resulted com- mon polymorphisms. CDH1 germline variants are present in EODGC patients in Chinese population, but they are mainly missense variants with unknown function which are likely associated with lymph node metastasis and OS.