Both groups of patients had similar baseline PCs and time to PC nadir under heparin treatment, but those with detectable anti‐PF4 IgG exhibited a more severe thrombocytopenia, as illustrated by their lower PC nadir (median: 35 G/L vs. 54 G/L in patients with or without anti‐PF4 IgG, respectively, p = .006; Table 2) and their higher PC drop (Figure S2). The gene discussed is PF4; the disease is Thrombocytopenia.