Volume 86, Issue 3, Pages 461-464 (September 2014) Molecular diagnostics in renal allograft biopsy interpretation: potential and pitfalls  Mark Haas  Kidney International  Volume 86, Issue 3, Pages 461-464 (September 2014) DOI: 10.1038/ki.2014.129 Copyright © 2014 International Society of Nephrology Terms and Conditions

Figure 1 Potential use of gene expression microarray studies of biopsy tissue and peripheral blood as an adjunct to morphologic diagnosis and in guiding therapy in donor-specific antibody (DSA)-positive renal allograft recipients. For the foreseeable future, such studies do not appear to be warranted in patients whose biopsies meet Banff 20136 morphologic criteria for active antibody-mediated rejection (ABMR) (top set of morphologic biopsy findings) or show no evidence of microvascular inflammation, thrombotic microangiopathy (TMA), endarteritis, or peritubular capillary C4d deposition (third set of biopsy findings from top). However, when the morphologic findings are equivocal or suspicious regarding active ABMR (second set of biopsy findings), gene expression studies on the biopsy tissue may prove useful in guiding therapy if thresholds for one or more sets of pathogenesis-based transcripts that differentiate DSA-positive ABMR-positive from DSA-positive ABMR-negative biopsies with acceptable sensitivity and specificity are identified and validated. Likewise, gene expression studies on whole blood may be useful in guiding treatment in patients who are unable to undergo an allograft biopsy, or whose biopsy is inadequate for diagnosis of ABMR, as discussed in the text. AMA, alternate macrophage-associated transcripts; CAT, cytotoxic T cell-associated transcripts; ENDAT, endothelial activation- and injury-associated transcripts; g + ptc, sum of Banff glomerulitis and peritubular capillaritis scores; GRIT, interferon-γ- and rejection-induced transcripts; NKAT, natural killer cell-associated transcripts; PBT, pathogenesis-based transcript set; v, Banff vasculitis score. Kidney International 2014 86, 461-464DOI: (10.1038/ki.2014.129) Copyright © 2014 International Society of Nephrology Terms and Conditions