GSTM1 and colorectal carcinoma: The studied polymorphism of the GSTM1 gene is based on a deletion of both gene alleles (genotype null/null) and results in a lack of protein product, so it can be assumed that deficiency of this detoxification enzyme glutathione S-transferase μ1 in connection with increased exposure to carcinogenic substances of red meat is a risk factor for CRC development.