Numerous nonclonal chromosomal aberrations arising in residual recipient hematopoietic cells following allogeneic bone marrow transplantation.

A young female patient in a second remission of acute lymphoblastic leukemia underwent bone marrow transplantation after total body irradiation and high-dose cytarabine from her HLA-matched brother. Following successful engraftment, mixed chimerism was seen 75 days post transplant. The karyotype contained numerous abnormalities in residual recipient cells. Chromosomes 1, 7, 13, and X were significantly more affected than other chromosomes. The high-frequency breakpoints identified were 1p22.2, 5q31.2, and 13q14.2. Some karyotypes specific for leukemia, such as t(9;22)(q34.1;q11.2) and t(8;21)(q22.2;q22.2), not seen with the original disease, were also present. As the frequency of aberrant chromosomes increased markedly with time, donor leukocytes were infused 14 months after BMT, which effectively eradicated the abnormal karyotypes.