DNA Contents of Chromosome Ph ¹ and Chromosome 21 in Human Chronic Granulocytic Leukemia

The Philadelphia chromosome, characteristic of chronic granulocytic leukemia, contained 61+/-1 percent as much DNA as a number 21 (or 22) chromosome from which it is believed to be derived. The remaining 39 percent represents 0.5 percent of a diploid chromosome complement, approximately 2 x 10(7) nucleotide pairs; the method used was not sensitive enough to detect whether it had been translocated to other chromosomes.