“…Since the initial description, over 25 families with ADA deficiency and immunodeficiency have been described in the literature [1, 17,23,24,42,52,59,71,73,82,88,90,119,124,128,131] and many more cases have been found [8,38,41,87,100,114]. Approximately 80-90}~, of the patients are indistinguishable clinically as well as by in vitro tests of immune function from other patients with SCID as described in Chapter 2.…”