What is Translocation?
Sometimes pieces of two chromosomes that are not homologous break off at the same time. If the broken pieces are re-attached to the opposite (in this case the non-homologous) chromosomes, the result is a translocation, as seen below.
The best known example of a translocation is the Philadelphia chromosome. This is simply chromosome number 22 that has lost a portion in exchange a small portion of chromosome number 9. This chromosome is named after the city where the abnormality was first discovered, and is responsible for causing chronic myelogenous leukemia.