Two complex translocations in chronic granulocytic leukemia involving chromosomes 22, 9, and a third chromosome.

Among 13 Ph-positive cases of chronic granulocytic leukemia (CGL), banding studies revealed two with complex rearrangements involving translocation of the long arm of number 22 to another autosome and a segment of that chromosome translocated to the long arm of number 9. In a patient with both CGL and sickle cell anemia, the 3-way rearrangement involved chromosomes 5, 9, and 22; and he also had a second Philadelphia chromosome and two constitutional variants: pericentric inversion of the other number 9 chromosome and satellite polymorphism in the G group. The karyotype of the leukemic cells was interpreted as: 47,XY,inv(9) (p11q13),t(5;9;22)(q13;q34;q11)+del(22)(q11). In the second patient, the complex translocation in the Ph-positive cells involved chromosomes 3, 9, and 22, resulting in a karyotype interpreted as: 46,XX,t(3;9;22)(p21;q34;q11). Several reports indicate that an abnormality of chromosome 9 is not essential for the development of Ph-positive CGL, but the very high frequency of its involvement (including these unusual translocations) suggests that some type of non-random somatic association may exist between 9q and 22q which makes simultaneous breakage likely. Attempts to correlate specific types of pH chromosome rearrangements with the clinical course of CGL must await the identification of more cases and longer follow-up.