Dr. Pui Y. Lee, a pediatric rheumatologist, leading researcher and clinician, joins us today to lend his insights on Deficiency of Adenosine Deaminase 2 or "DADA 2". What is this disease and how common is it? What is the underlying pathophysiology, the role of genetic screening and the most useful diagnostic tools? We'll also cover treatment options for DADA 2, the prognosis most patients face, plus the future of research for this condition.