Background: Detection of recipient versus donor disparities in microsatellite DNA regions (short tandem repeats [STR]) allows for sensitive and specific monitorization of the degree of hematopoietic chimerism. It is well known that disparities between donor and recipient in various polymorphic systems (mainly human leukocyte antigen [HLA]) are associated with an increased incidence of graft-versus-host disease (GvHD). However, the possible biological role of STR discrepancies in GvHD development has not yet been well established.
Methods: We evaluated 149 consecutive patients with hematologic malignancies receiving peripheral blood stem-cell transplantation from a human leukocyte antigen-identical sibling donor. A total of 15 STR regions were analyzed using the PowerPlex16 kit and classified as identical when recipient and donor share the same alleles, and mismatched when at least one of the alleles differed.
Results: Higher severity of acute GvHD (II-IV, P=0.043) and shorter 5-year overall survival (P=0.016) was found in patients displaying more than 10 mismatches with respect to their donor. Additionally, higher risk of transplant-related mortality (P=0.019) was found in recipient-donor pairs with discrepancies in the D13S317 STR marker.
Conclusion: The present data suggest that genetic incompatibilities outside the human leukocyte antigen region between donors and recipients influence the outcome of patients receiving stem-cell transplantation. In addition, disparities in the neighboring D13S317 region could influence transplant-related mortality.