Association of genetic variants with colorectal cancer in the extended MENA region: A systematic review

Abstract

Colorectal cancer (CRC) is the third most common cancer worldwide and the third leading cause of cancer-related death. It is a heterogeneous disease that develops through different genetic and epigenetic mechanisms. To date, no comprehensive systematic review study has been performed on the extended MENA (eMENA) region to investigate the genetic risk factors for familial and sporadic CRC. This study aimed to systematically analyze the genetic variations that are significantly associated with CRC in the eMENA region. We searched four literature databases (PubMed, Scopus, Science Direct, and Web of Science) from the time of inception until May 2019 using broad search terms to obtain all the reported genetic data related to the eMENA patients with CRC. Variants with OR>1 that are associated with CRC were captured. A total of 1,200 studies were obtained from our search method; 27 studies met the inclusion criteria for our systematic review. A total of 8,230 CRC patients and 7,611 controls were captured. Of these, 1,941 patients were found to carry 46 variants in 33 different genes that are distributed throughout nine eMENA countries. Interestingly, 19 variants were unique to the CRC patients in the eMENA region (rs63750042, rs267608121, rs267608119, rs2069426, rs63750875, rs16940372, rs4775053, rs4775072, rs9652472, rs35509282, rs2985, rs371608994, rs6983267, rs419598, rs2222722). This is the first systematic review to capture the spectrum of variants that are significantly associated with CRC in the eMENA region. There seems to be a distinctive clinical picture in the eMENA patients with CRC, and the range and distribution of variants among patients from the eMENA region are different from those noted in other affected ethnic groups.