Genetic factors play an important role in numerous hematological disorders. The study of their molecular basis has increased tremendously. The DNA and various types of RNA are involved in cell replication as well as protein synthesis. These biological processes are under continuous biological regulation. They are subjected to various changes that disturb their normal functions. These include point mutations e.g. missense and nonsense mutations; deletions, insertions. Oncogenes and tumor suppressor genes are important factors responsible for the malignant disorders. Proto¬oncogenes act by stimulating growth of target cells. Various mechanisms of transforming proto-oncogenes to oncogenes include chromosomal translocations, point mutations, and amplification.Tumor supressor genes function to inhibit growth of target cells. Loss of one or more of these genes leads to malignancy