They often lose the ability to properly repair DNA, e.g., due to mutations in genes such as BRCA1, BRCA2, (breast cancer genes 1 and 2; essential for homologous recombination repair of DNA damage, chromatin remodelling, and maintaining genomic stability), MLH1 (MutL Homolog 1; the human homolog of the bacterial MutL gene key in DNA mismatch repair pathway, it corrects base-pair mismatches that occur during DNA replication), which leads to the growth of further mutations and even greater tumour aggressiveness. This evidence concerns the gene MLH1 and breast carcinoma.