IgG3: The mean IgG3 levels tend to be higher in idiopathic hypersomnia patients than in HLA-negative controls (p = 0.016), HLA-positive controls (p = 0.029), and narcolepsy patients with low IgG level (p = 0.0105) (Table 2, Fig. 5). This evidence concerns the gene IGHG3 and idiopathic hypersomnia.