A 9-month-old girl with a history of recurrent pulmonary infections is found to have a congenital deficiency of adenosine deaminase, which is associated with a viual absence of lymphocytes in her peripheral lymphoid organs. What is the appropriate diagnosis?

SCID Group of disorders of T and B lymphocytes Characterized by recurrent viral, bacterial, fungal, and protozoal infections. Many infants with SCID have severely reduced volumes of lymphoid tissue and an immature thymus that lacks lymphocytes. In some patients, lymphocytes fail to develop beyond pre-B cells and pre-T cells. ADA deficiency causes the accumulation of intermediate products, which inhibit DNA synthesis and are toxic to lymphocytes. These children cannot survive beyond early infancy unless they are raised in a sterile environment ("bubble children"). None of the other choices are associated with ADA deficiency. Diagnosis: Severe combined immunodeficiency