Formation of double minutes by breakdown of a homogeneously staining region in a refractory anemia with excess blasts.

A patient suffering from refractory anemia with excess blasts in transformation had four different bone marrow karyotypes. These were 46,XY; 45,X,-Y; 45,X,-Y, 5q-,19q+; and 43,X,-Y,-9,-17,5q-,+dmin. The most plausible explanation for this is proposed to be formation of a homogeneously staining region on chromosome #19, followed by its breakdown into double minutes.