IgA pemphigus is further subdivided into two types of pemphigus disease: (1) SPD type, which primarily manifests with antibodies concentrated in the upper epidermis (targeting desmocollin 1), and (2) IEN type, which manifests with antibodies concentrated throughout the epidermis (targeting desmogleins 1 and 3). The gene discussed is DSC1; the disease is Platelet storage pool disease.