In subjects with allergy only to dog, serum concentrations of specific IgE and IgG4 to dog dander but not to cat dancer were higher than those in subjects without allergy to dog or cat (dog-specific IgE, 3.09 vs 0.26 kUA/L, P < 0.001; dog-specific IgG4, 2.15 vs 0.85 kUA/L, P < 0.001). This evidence concerns the gene IGHE and allergic disease.