Immunodeficiency Due to a Classical Component Pathway Complement Deficiency, also known as immunodeficiency due to c1, c4, or c2 component complement deficiency, is related to periodontal ehlers-danlos syndrome and ehlers-danlos syndrome, periodontal type, 2. An important gene associated with Immunodeficiency Due to a Classical Component Pathway Complement Deficiency is C1QA (Complement C1q A Chain), and among its related pathways/superpathways are Innate Immune System and Complement cascade. Related phenotypes are Increased shRNA abundance (Z-score > 2) and Decreased viability