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

Abstract 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.