Cancer is simply due to the mutations at the genetic level, commonly known as genetic disorder. In this condition the cells suffer from uncontrolled growth of cell division. These mutations can be acquired or may occur in somatic cells. Somatic cell mutations cannot be inherited while germ line mutations are inherited. In general, cancer cells have more genetic changes than normal cells. But each person’s cancer has a unique combination of genetic alterations. Some of these changes may be the result of cancer, rather than the cause. As the cancer continues to grow, additional changes will occur. Even within the same tumor, cancer cells may have different genetic changes. The genes that contribute to cancer development are tumor suppressor genes, Oncogenes and DNA repair genes. Tumor suppressor genes are protective genes and they limit cell growth by monitoring how quickly cells divide into new cells, repairing mismatched DNA and controlling when a cell dies. These include BRCA1, BRCA2, and p53 or TP53. When a tumor suppressor gene mutates, cells grow uncontrollably. And they may eventually form a tumor. Oncogenes turn a healthy cell into a cancerous cell. Mutations in these genes are not known to be inherited. Common oncogenes are HER2 and the RAS family of genes.The role of SMARCA4 gene has been least explored in breast cancer.