Genetic testing was nondiagnostic in thirteen children: suspected MSMD (2), hyper-IgE syndrome (2), severe congenital neutropenia (2), hemophagocytic lymphohistiocytosis (1), hyper-IgM (1), chronic granulomatous disease (1), combined immunodeficiency (1), unclassified immune dysregulation (1), C1q deficiency (1), and IL17 pathway defect (1). Here, IL17A is linked to immunodeficiency due to a classical component pathway complement deficiency.