The Philadelphia chromosome (Ph) represented a finding of chronic myeloid leukemia (CML) in most cases which formed from t (9; 22) (q34; q11) resulting in the Breakpoint cluster region‐Abelson tyrosine‐protein kinase1 (BCR‐ABL1) fusion gene. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.