The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
Yan Zhang , Tiantian Han , Didi Guo , Ningning Luo , Guanghua Lu , Fanfeng Bu
Background: Germline mutations play an important role in cancer risk and susceptibility. With the growing implementation of next generation sequence of multiple gene panel, an increasing number of cases that carry two or more inherited cancer-predisposing alleles in the same individual are being described. However, understanding the impact of these combined mutations on the patient's phenotype can be particularly challenging. To further understand these combined mutations, we analyze the genetic susceptibility mutations of Chinese solid tumor patients to explore the characteristics of multiple germline variants. Methods: Genetic mutations were reviewed in cancer patients who underwent hybridization capture based next-generation sequencing (NGS). The pathogenicity of germline mutations was categorized based on American College of Medical Genetics and Genomics (ACMG) guidelines, and only pathogenic and likely pathogenic variants were included in this study. Results: Germline variants were identified in 1267 individuals, including 1244 patients harbored one germline mutations and 23 patients carried ≥2 germline mutations, and there was no age difference in the two groups (57 vs 55, p = 0.62). In the ≥2 germline mutations group, genes most frequently involved were BRCA1/2 (12/47, 25.5%), CHEK2 (4/47, 5,1%), TP53(4/47, 5,1%) and MUTYH (4/47, 5,1%). Most of these variants affected DNA damage repair pathways [57% homologous recombination repair (HR), 15% mismatch repair (MMR)]. Besides, double variants in HR and HR pathway were found in 8 patients, HR and MMR pathway were found in 5 patients. Surprisingly, the 50-year-old man with colorectal cancer with three pathogenic variants of the [FH -BRCA2- FANCD2] genes showed a high aggregation of tumors associated with leiomyomatosis and renal cell cancer and HBOC. Conclusions: We found over 56.5% patients with multiple pathogenic variants in DNA damage repair pathways, which may have important implications for the treatment strategy for these patients. Next-generation sequencing technologies now provide the opportunity to perform simultaneous parallel testing of large numbers of inherited cancer genes, which could guide the clinician as to what the effect of each combination of mutations might be.
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