RATIONALE: Studying samples of blood from patients with cancer in the laboratory may help doctors learn more about changes that occur in DNA and identify biomarkers related to cancer.

PURPOSE: This research study is looking at blood samples in young patients with cytopenia after undergoing a donor stem cell transplant.

OBJECTIVES:

Primary

• To study hematopoietic chimerism in whole blood and different cell populations (i.e., CD14, CD15, CD 56, CD3, and CD19) as well as in dendritic cells and regulatory T cells after allogeneic hematopoietic stem cell transplantation with reduced intensity conditioning in patients with refractory cytopenia.
• To compare the results of chimerism obtained with standard short tandem nucleotide polymorphism PCR (sensitivity 1%) with those obtained with single nucleotide polymorphisms PCR (sensitivity 0.1- 0.01%).

Secondary

• To evaluate the relationship between mixed chimerism and hematological engraftment, overall survival, and event-free survival.
• To study the impact of mixed chimerism in plasmacytoid dendritic and regulatory T cells on the incidence of acute and chronic graft-versus-host-disease.

OUTLINE: This is a multicenter study.

Peripheral blood is collected from patients and donors prior to hematopoietic stem cell transplantation (HSCT). Patients also undergo blood sample collection on days 30, 60, 100, and 180 after transplantation. Peripheral blood cells are enriched and separated into lineage-specific subpopulations (i.e., CD3, CD14, CD15, CD19, and CD56) which are then divided equally for either DNA isolation via PCR or for flow cytometry. DNA concentrations in pre-HSCT donor and patient samples and in post-HSCT subpopulation samples are determined using quantitative real-time PCR. Samples are also analyzed for quantification of chimerism and detection of genetic markers via short tandem repeats- and sequence nucleotide polymorphism-based chimerism analyses.

DISEASE CHARACTERISTICS:

• Diagnosed with refractory cytopenia

  • Hypocellular bone marrow and normal karyotype

• Underwent stem cell transplantation (SCT) from an HLA identical (8/8) sibling, an HLA identical (10/10) relative, or an HLA identical or single allelic disparate unrelated donor

  • Received a preparative regimen including either thiotepa or fludarabine phosphate

• Concurrently enrolled on EWOG-MDS-2006

PATIENT CHARACTERISTICS:

• Not specified

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics