Pentasomy 21 in leukemia complicating Diamond-Blackfan anemia

Abstract We present the cytogenetic pattern of a leukemic infant with Diamond-Blackfan anemia (DBA). The karyotype was characterized by clonal evolution involving consecutive gains of chromosome 21 up to pentasomy. No chromosomal changes were present in normal lymphocytes. Such a karyotype evolution has been described in some cases of acute leukemia associated with Down Syndrome, but rarely in non-Down cases.