Objective: Deficiency of the purine salvage enzymes adenosine deaminase (ADA) or purine nucleoside phosphorylase (PNP) leads to severe combined immune deficiency (SCID). Since these enzymes are found in all cells, other tissues and organs are also affected, though more variably.

Materials and Methods: Here we describe the clinical course and treatment of one PNP deficient and 4 ADA deficient patients who were diagnosed in infancy. All had very low T-cell count and immunoglobulins, consistent with T-B-NK- SCID.

Results: Hematopoietic stem cell transplantation (HSCT) was performed in two patients with ADA deficiency. The ADA deficient patient who was treated with haploidentical HSCT (haplo-HSCT) died due to complications of HSCT. One of the ADA deficient patients died before HSCT and another ADA deficient patient is currently being treated with enzyme replacement treatment (ERT). The PNP deficient patient was treated with unrelated cord blood HSCT.

Conclusion: With this study, it was highlighted once again that the deficiency of purine salvage enzymes is important subgroup of SCIDs in Turkey.