Most previous reports describing the different clinical phenotypes of RAG deficiency presented pediatric patients with late onset of combined immunodeficiency characterized by CD4 lymphopenia and/or impaired T cell function and hypo- or agammaglobulinemia with defective B cell differentiation [7,9,10,13–19] or early onset autoimmunity and granulomatous disease [8–11,15,16,20]. Here, CD4 is linked to Autoimmunity.