Gene fusion is a biological process where two different genes combine to form a single hybrid gene. This can occur naturally through various mechanisms, such as chromosomal rearrangements or during the development of certain diseases, like cancer. The resulting fusion gene can produce a new protein that may have altered functions compared to the original proteins. In research and medicine, gene fusion is significant because it can lead to the development of targeted therapies. For example, the BCR-ABL fusion gene is associated with certain types of leukemia, and understanding this fusion has helped in creating specific treatments that inhibit its activity.