Harmful Genetic Variations: Mutations
There are a group of variations in coding and regulatory regions that result in harmful effects. These are called mutations. Mutations alter the gene's instructions for its corresponding protein. If many such variations occur in critical genes within the same cell, cancer may develop.
In chronic myelogenous leukemia, a translocation occurs between chromosome 9 and 22. This rearrangement of genomic material creates a fusion gene called Bcr-Abl that produces a protein (tyrosine kinase) thought to promote the development of leukemia. The drug Gleevec blocks the activation of the Bcr-Abl protein.