A 51 year old male is found to have splenomegaly on physical examination. His blood work shows a haemoglobin of 110g/L, white blood cell count of 122 with a left shift and platelet count of 900,000. He is immediately referred to a haematologist, who suspects chronic myelogenous leukemia.
What is the abnormality in CML and what therapies exist to treat it?