What causes chronic myelogenous leukemia?
Chronic myelogenous leukemia is a rare type of leukemia that tends to affect older males. More than 90% of cases are due to a gene abnormality caused when two chromosomes swap sections with each other. There are 23 chromosomes in humans, and in patients with chronic myelogenous leukemia chromosomes 9 and 22 within blood cells exchange bits of genetic material to form a Philadelphia chromosome, named after the city where it was discovered. The new gene on this chromosome makes a protein called tyrosine kinase that allows white blood cells to grow out of control; moreover, these abnormal white blood cells tend not to become old and die. The bone marrow, where red blood cells, white blood cells, and platelets are made, becomes filled with white blood cells crowding out the normal cells and damaging the bone marrow itself. This can impair the ability of the bone marrow to manufacture normal amounts of blood cells.
