title: Cytogenetic Variation of B-Lymphoblastic Leukemia With Intrachromosomal Amplification of Chromosome 21 (iAMP21): A Multi-Institutional Series Review.
abstract: OBJECTIVE
  B-lymphoblastic leukemia (B-ALL) with intrachromosomal amplification of chromosome 21 (iAMP21) is a relatively uncommon manifestation of acute leukemia and limited predominantly to the pediatric population. Case-specific information regarding flow cytometric, morphologic, and laboratory findings of this subtype of leukemia is currently lacking.
  
  
  METHODS
  We searched the databases of three large institutions for lymphoblastic leukemia with iAMP21 from 2005 through 2012 and analyzed the clinicopathologic features.
  
  
  RESULTS
  We identified 17 cases with five or more RUNX1 signals on interphase nuclei, 14 of which were consistent with the Children's Oncology Group (COG) definition for iAMP21—namely, the presence of three or more RUNX1 signals on one marker chromosome. These cases showed a statistically significant lower peripheral WBC count and older age at diagnosis compared with all pediatric cases of B-ALL. We also identified three cases with increased RUNX1 signals scattered on multiple marker chromosomes that did not meet the COG definition of iAMP21 but showed similar 21q instability and older age at presentation.
  
  
  CONCLUSIONS
  Our findings not only demonstrate that B-ALL with iAMP21 is truly a distinct clinicopathologic entity but also suggest that a subset of cases of B-ALL with iAMP21 can show variable cytogenetic features.
authors.affiliation: From the Stanford University Medical Center, Stanford, CA; ryancj@stanford.edu.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Johnson
authors.affiliation: Boston Children's Hospital, Boston, MA; and.
authors.forename: Olga K
authors.initials: OK
authors.lastname: Weinberg
authors.affiliation: Oregon Health and Science University, Portland.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Cascio
authors.affiliation: From the Stanford University Medical Center, Stanford, CA;
authors.forename: Gary V
authors.initials: GV
authors.lastname: Dahl
authors.affiliation: From the Stanford University Medical Center, Stanford, CA;
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Mitton
authors.affiliation: Boston Children's Hospital, Boston, MA; and.
authors.forename: Lewis B
authors.initials: LB
authors.lastname: Silverman
authors.affiliation: From the Stanford University Medical Center, Stanford, CA;
authors.forename: Athena M
authors.initials: AM
authors.lastname: Cherry
authors.affiliation: From the Stanford University Medical Center, Stanford, CA;
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Arber
authors.affiliation: From the Stanford University Medical Center, Stanford, CA;
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ohgami
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics; D020732:Cytogenetic Analysis; D005260:Female; D005434:Flow Cytometry; D005784:Gene Amplification; D006801:Humans; D008297:Male; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D055815:Young Adult
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; C493728:RUNX1 protein, human
keywords: Clinical and molecular epidemiology; Cytogenetics and molecular genetics; Flow cytometry; Hematopathology; Pediatric acute lymphoblastic leukemia; iAMP21