XPD gene polymorphism and colorectal cancer risk

TO THE EDITOR We examined Rezaei et al's paper (1) and we are interested in the subject. The study was about the functions of repair genes, their mechanisms in cancer development and associated polymorphisms which increase susceptibility to CRC. As we know Single nucleotide polymorphisms (SNPs) are the most common genetic sequence variation in human genome. SNPs are associated with population diversity, disease susceptibility and individual response to medical therapy (2, 3). In the other hand, the development of CRC is associated with environmental factors, genetic susceptibilities, and their interaction (4). Polymorphisms in DNA repair genes contribute to the variations in individual genetic susceptibility to many types of cancers, such as lung cancer, breast cancer and gastric cancer (5–9). The study population of this paper was heterogeneous in terms of colorectal cancer. The authors mentioned that of 88 colorectal cancer patients enrolled in this study, 32 patients (45%) had a positive family history for colorectal cancer in their first-degree relatives. They didn’t determine the type of familial CRC in these