Dose Study of Thymus Transplantation in DiGeorge Anomaly, IND 9836, #932.1

Thymus tissue (from unrelated donor), thymus donor, and thymus donor's birth mother screened for safety. CTTI was done under general anesthesia. Cultured thymus tissue was implanted into quadriceps. Thymus dose at least 4grams/m2 body surface area (0.2 grams/kg body weight) and not \>18 grams/m2 body surface area (1.0 grams/kg body weight). At time of CTTI, skin biopsy was obtained to look for preexisting T cells. 2-3 months post-CTTI allograft biopsy was done to evaluate for thymopoiesis \& graft rejection. At time of biopsy, skin biopsy done to look for T cell clonal populations. (Allograft biopsy not done if subject medically unstable.) Post-CTTI, subjects followed by immune evaluations, using blood samples.

Parental parathyroid donors screened for eligibility and safety. If both parents meet eligibility criteria, the parathyroid will be harvested from parent who shares the most Human Leukocyte Antigens (HLA) alleles with thymus donor. Parathyroid harvest \& transplant preferably done at same time as CTTI. (If parathyroid transplant cannot be done at same time, then it is done within 3-8 weeks of CTTI.) Parathyroid harvest done under general anesthesia. One parathyroid gland is minced \& placed in quadriceps muscle; there is no dose in mg. No biopsy done of the parathyroid. Parathyroid donors are monitored as outpatients until recipients' discharge. Recipients' calcium and PTH levels are monitored indefinitely.