Analysis of Hematopoietic Stem Cell Transplant Engraftment: Use of Loss or Gain of Microsatellite Alleles to Identify Residual Hematopoietic MalignancyLin, Ming-Tseh MD, PhD*; Tseng, Li-Hui MD, PhD*,†; Beierl, Katie BS*; Harada, Shuko MD*; Hafez, Michael J. MS*; Eshleman, James R. MD, PhD*,‡; Gocke, Christopher D. MD*,‡Author Information Departments of *Pathology ‡Oncology, Johns Hopkins University School of Medicine, Johns Hopkins Hospital, Baltimore, Maryland †Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan This publication was made possible by Grant Number R21HG004315 from NHGRI/NIH to CDG. Reprints: Christopher D. Gocke, MD, Department of Pathology, Park SB202, 600 North Wolfe Street, Baltimore, MD 21287 (e-mail: [email protected]). Diagnostic Molecular Pathology: December 2011 - Volume 20 - Issue 4 - p 194–202 doi: 10.1097/PDM.0b013e31821dac16 Buy Metrics Abstract Polymorphic short tandem repeat (STR), or microsatellite, loci have been widely used to analyze chimerism status after allogeneic hematopoietic stem cell transplantation. The presence of a patient's DNA, as identified by STR analysis, may indicate residual or recurrent malignant disease or may represent normal hematopoiesis of patient origin. The ratio of patient-derived to donor-derived alleles is used to calculate the relative amount of patient cells (both benign and malignant) to donor cells. STRs on chromosomes known to be gained or lost in a patient's tumor are generally ignored because it is difficult to perform meaningful calculations of mixed chimerism. However, in this study, we present evidence that STR loci on gained or lost chromosomes are useful in distinguishing the benign or malignant nature of chimeric DNA. In the peripheral blood or bone marrow of 4 hematopoietic stem cell transplantation patients with leukemia or lymphoma, we identified tumor DNA on the basis of STR loci showing copy number alteration. We propose that a targeted evaluation of STR loci showing altered copy number in posttransplant chimerism analysis can provide evidence of residual cancer cells. © 2011 Lippincott Williams & Wilkins, Inc.