Targeted genetic testing can be performed by drawing blood or by taking other specimens, such as bone marrow fluid from the patient or pathological tissue removed from the patient. For example, in hematologic malignant diseases, the most common targeted gene test is acute promyelocytic leukemia. The most common method of targeted gene testing is to extract the patient’s bone marrow fluid through bone marrow aspiration and then do targeted gene testing to see if there is a specific targeted gene. Only patients who test positive for the target gene can have better results with retinoic acid therapy. For patients with chronic granulocytic leukemia, bone marrow cells are also obtained through bone marrow aspiration and then tested for target genes. Targeted gene testing can be done by blood sampling or through other means, depending on the condition.