Demonstration of Y/autosomal translocations using distamycin A.

The condensation of the brightly fluorescing Y-heterochromatin is prevented by cultivating leukocytes in a medium containing distamycin A. This technique provides a reliable method for the identification of those Y/autosomal translocations in which Y heterochromatin is involved. A case of a familiar Y/22 translocation and the distamycin A technique are described.