PhIP-seq is highly concordant with clinical results for the anti-SLA antibody, and yields finer mapping of the known SLA epitope by PhASER. (a) Heatmap comparing all patients for which clinical anti-SLA testing results were available (96 AIH patients, 11 controls). Patients positive for anti-SLA antibody by PhIP-seq (blue, bottom row) were all positive by clinical testing (blue, top row), and two additional positive patients were detected by PhIP-seq. SLA-negative AIH patients are noted in beige, and non-AIH patients were noted in gray, all of whom were negative for anti-SLA antibody using both assays. (b) Heatmap of SLA/LP-positive (pos) AIH patient reactivity (n = 5) to SLA/LP peptide 18 (peptide sequence at the bottom of the heatmap) with stop-codon substitutions at each position, starting at SLA/LP amino acid 389. The sequence of the previously reported minimal SLA/LP epitope is underlined. Reactivity to SLA/LP became detectable (blue) after the peptide extended through position 414, and was not detected with shorter peptide truncations (orange).