IGHE and common variable immunodeficiency: Despite these limitations, it is worth noting that these studies show that individuals with a low level of IgE, with normal values for the other immunoglobulins, present recurrent respiratory infections, suffer from autoimmune diseases, and upper and lower airway diseases [23,24,25,26], similar to those described in patients with CVID [6,7,8], IgGSD [9] or with SIgGD [8], SIgAD [11,12], and SIgM D [13,14].