Van Beek et al. (2012) from Germany attempted to validate the biochip IIF technique and demonstrated a high sensitivity and specificity for IIF microscopy on monkey esophagus (100% for PV; 98% for PF; overall specificity 89.1% for pemphigus), anti-Dsg3 reactivity (98.5%, 100% for PV), and anti-Dsg1 reactivity (90%, 99.6% for PF). Here, DSG1 is linked to acquired polycythemia vera.