Banded karyotypes from bone marrow: a clinical useful approach.

We have developed a new protocol for the preparation of banded chromosomes from human bone marrow. This protocol incorporates new procedures with improvements in conventional ones to rapidly produce high quality banded karyotypes from bone marrow aspirates. Tissue culture is completely eliminated and replaced with a truly direct method of chromosome preparation in which a small amount of marrow is treated with a solution containing trypsin, hypotonic salts and colcemid (THC). The THC protocol, when compared with standard short term culture methods for marrow chromosome preparation, produces more extended and more readily banded chromosomes. Rapid banding is further facilitated by replacement of standard G-banding technique with Wright's staining. The technical developments allow karyotypic analysis within 2-4 h after receipt of the specimen. The high quality and rapidity of the THC protocol have important implications for the clinical usefulness of cytogenetic analysis of bone marrow in studying congenital defects as well as leukemias and lymphomas.