The Ph1 translocation [t(9;22)(q34;q11)]

The Philadelphia chromosome arises by reciprocal
translocation between a chromosome 22
and a chromosome 9. The breakpoints are in
9q34 and 22q11. A good half of the long arm of a
chromosome 22 is translocated to the long arm
of a chromosome 9. A very small segment of the
distal long arm of a chromosome 9 (9q34), not
visible under the light microscope, is translocated
to a chromosome 22. The Philadelphia
chromosome (22q–) consists of the short arm
and the proximal one-third of the long arm of a
chromosome 22 and the small distal segment
from the long arm of a chromosome 9. For demonstration
of the Philadelphia translocation