Background. Dedicator of cytokinesis 2 (DOCK2) deficiency is a rare autosomal recessive combined immunodeficiency presenting with very early onset, severe bacterial and viral infections. In DOCK2 deficiency; T, B and NK cell numbers are decreased and functions are impaired resulting in severe atrophy of secondary lymphoid tissues. The aim of this report is to provide information on clinical and laboratory features and hematopoietic stem cell transplantation (HSCT) outcomes of a DOCK2 deficient patient. The patient was diagnosed by using a targeted next generation sequencing primary immunodeficiency (PID) panel. Lymphocyte subsets were measured by flow-cytometry.

Case. Here, we describe a patient with DOCK2 deficiency presented with severe combined immunodeficiency. He underwent HSCT without conditioning regimen before the genetic diagnosis and developed hemophagocytic lymphohistiocytosis(HLH) due to Epstein-Barr virus (EBV) infection.

Conclusions. Genetic testing is necessery for early diagnosis of DOCK2 deficiency. The curative treatment should be HSCT soon after diagnosis.

Keywords: DOCK2 deficiency, EBV associated hemaphagocytic lymphohistiocytosis, hematopoietic stem cell transplantation, hemophagocytic lymphohistiocytosis, severe combined immune deficiency