Association between HLA and anti-PF4/H antibody levels. (A) HLA allele associations: top row, distribution of OD values; middle row, odds ratio for having an OD value above vs below a given cutoff; and bottom row, significance of association across all possible cutoffs (95% confidence intervals in pink). (B) HLA amino acid residue associations: top row, distribution of OD values; middle row, odds ratio for having an OD value above vs below a given cutoff; and bottom row, significance of association across all possible cutoffs (95% confidence intervals in pink). (C) Two views of candidate amino acid residues within DRB1 driving risk for anti-PF4/H antibody development (Protein Data Bank code: 1A6A). *Significance within a 5% false discovery rate.