IgG subclass distribution in HIT/HITT. Distribution of IgG subclasses as a percentage of total anti-heparin/PF4 IgG in 34 HIT/HITT patients grouped by FcγRIIA genotype. Each panel represents the subclass distribution (IgG_1-4 ) of patients with H/H¹³¹ (n = 7), H/R¹³¹ (n = 19), or R/R¹³¹ (n = 8). Open symbols refer to patients with HIT (n = 12), and solid symbols refer to patients with HITT (n = 22).