Primary immune deficiency diseases are a heterogeneous group of genetic disorders of the immune system. To date, more than 300 disease-causing genes are reported. Primary antibody deficiencies are associated with increased susceptibility to infections, autoimmunity and malignancy. Th 17 disorders represent with recurrent S. Aureus infections and chronic/invasive fungal infections. Whole exome sequencing detects many novel variants/genes without known consequences. We perform immuno-functional assays including extended immunophenotyping, different variant-specific signaling pathways using different cellular systems to prove the causal defect of these variants and document novel PID subtypes which will enhance the understanding of the pathogenesis of PID.