 These syndromes are caused by mutations that affect the maturation of the hematopoietic progenitor cells, which are the precursors of both B and T cells.A number of genetic defects can cause SCID, including IL-2 receptor gene loss of function, and mutation resulting in deficiency of the enzyme adenine deaminase.Autoimmune polyendocrine syndrome type 1, is a rare genetic autoimmune syndrome that results from a genetic defect of the thymus tissues.