• Associations of Lactose Intolerance-Related SNPs in the LCT Gene and Colorectal Cancer risk
  • Dr. Ghazaleh Eslamian,1,* Saba Ghoreishi,2 Dr. Majid MesgarTehrani,3 Dariush Norouzian,4 Mohammad Mahdi Eslami,5
    1. Assistant Professor Faculty of Nutrition and Food Technology Shahid Beheshti University of Medical Sciences Tehran, Iran
    2. Islamic Azad University ,Urmia , Iran
    3. Member of the Core Committee of the National Genomics Hub, Shahid Beheshti University of Medical Sciences, Tehran, Iran
    4. Full Professor, Pasteur Institute of Iran, Tehran, Iran
    5. Member of the Bioinformatics Research Group, Nasim Research Institute, Tehran, Iran


  • Introduction: Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related mortality worldwide, with over 1.9 million new cases and 935,000 deaths reported in 2020. Its etiology is multifactorial, involving genetic predisposition, dietary habits, and lifestyle factors. The LCT gene, located on chromosome 2q21, encodes lactase-phlorizin hydrolase (LPH), the key enzyme in lactose metabolism. Polymorphisms in this gene, such as rs4988235 (-13910 C>T) and rs182549 (-22018 G>A), influence lactase activity and lactose intolerance (LI), and have been investigated for their potential association with CRC risk. While some studies and Mendelian randomization analyses suggest a protective effect of lactase persistence and milk consumption against CRC, others report inconsistent or null associations, varying by population and dietary context. Proposed mechanisms include altered calcium and vitamin D intake in LI individuals and gut microbiota dysbiosis caused by undigested lactose fermentation. However, discrepancies across studies highlight the need for further research accounting for gene–diet interactions, regional dietary differences, and population-specific genetic backgrounds. Understanding these associations may provide insights for personalized prevention strategies in populations with a high prevalence of lactose intolerance.
  • Methods: One of the most reliable sources in this research is the NCBI database. NCBI (National Center for Biotechnology Information) is a globally recognized resource that provides comprehensive biomedical and bioinformatics databases and tools. This site includes resources such as scientific articles, genetic and protein sequences, and bioinformatics analysis tools, helping researchers and clinicians to search, analyze, and interpret scientific and genetic data. The second software employed in this study is Mega Gene .Mega Gene (Mega Gene) is the first and only international software for analyzing genetic mutations (SNPs) in cancer-related genes and selecting drugs based on an individual’s genetic profile. Applications: 1. Analyzing the interactions of genetic mutations. 2. Drug selection based on genetic profile. 3. Evaluating and predicting side effects of chemotherapy drugs . Mega Gene assesses mutations and their association with cancer, enabling the selection of chemotherapy drugs with minimal side effects. First, genes associated with colorectal cancer were identified using the NCBI database. The abbreviations of these genes were then input from the SNP section of the same database. After analyzing the data related to polymorphisms and preparing the information, it was entered into the Mega Gene software. During the meta-analysis stage, the names of genes involved in colorectal cancer, their phenotypes, alleles, sample sizes, and the number of citations for each gene were recorded.
  • Results: With the investigations carried out using the Mega Gene software, we found that among the 103 genes involved in colorectal cancer, three genes account for the highest percentage, indicating that they have the highest number of polymorphisms. These three genes are: 1) CRP, with 6 SNPs and 3.42% influence 2) TLR2, with 5 SNPs and 2.85% influence 3) IL10, with 4 SNPs and 2.28% influence
  • Conclusion: Understanding these associations may provide insights for personalized prevention strategies in populations with a high prevalence of lactose intolerance. With the investigations carried out using the Mega Gene software, we found that some genes involved in colorectal cancer account for the highest number of polymorphisms, indicating that they may contribute to susceptibility.
  • Keywords: Colorectal Cancer, LCT Gene, Single Nucleotide Polymorphism (SNP), Lactose Intolerance, Mega Gene