To rule out the presence of the t(9;22) in a patient suspected of having CML, which tissue should be cultured?

Culturing bone marrow tissue is the most appropriate choice for ruling out the presence of the t(9;22) translocation, which is associated with chronic myelogenous leukemia (CML). The t(9;22) translocation results in the formation of the BCR-ABL fusion gene, which is a hallmark of CML.

Bone marrow is the primary site of hematopoiesis, where blood cells, including myeloid cells involved in CML, are produced. By analyzing bone marrow cells, cytogeneticists can directly assess for chromosomal abnormalities specific to CML, such as the Philadelphia chromosome resulting from the translocation.

In contrast, while blood from circulation can be tested for the presence of the Philadelphia chromosome, it is much less sensitive than testing bone marrow. Blood may not contain sufficient myeloid precursors, particularly in early stages of the disease. Amniotic fluid primarily contains fetal cells, and skin tissue does not typically participate in hematopoiesis; therefore, they are not suitable for diagnosing CML via the presence of the t(9;22).