Successful HLA-identical bone marrow transplantation in a patient with interferon-γ receptor 2 deficiency and disseminated Mycobacterium avium complex infection

Abstract

Interferon gamma receptor-2 (IFNγR2) deficiency is characterized by increased susceptibility to nontuberculous mycobacteria and intracellular pathogens. We report successful HLA-identical bone marrow transplantation (BMT) of a patient with this defect. A Qatari male born to consanguineous parents presented with a CMV positive urine culture, while blood and urine mycobacterial cultures were initially negative. Bacille-Calmette-Guerin (BCG) vaccine was not administered due to a history of IFN-γ R2 deficiency in his deceased older sister. The patient was found to have the same defect. Parents initially refused BMT. He received prophylactic azithromycin but developed disseminated Mycobacterium avium complex (MAC) infection requiring an aggressive regimen including amikacin, azithromycin, ethambutol, linezolid, rifampin and moxifloxacin. CMV infection was treated with ganciclovir, foscarnet, and CMV immune globulin. Splenectomy was performed at age 9 months, due to massive hypersplenism with subsequent growth of MAC. CMV DNA was positive until age 11 months, while mycobacterial blood cultures were positive until age 10 months. At age 13 months, he underwent bone marrow transplantation from his HLA-identical father. Pre-transplant conditioning included busulfan, cyclophosphamide, and antithymocyte globulin (ATG). Post-transplant graft vs. host disease prophylaxis included methotrexate and cyclosporine. RFLP analysis revealed 98% donor cells on day +32 post-transplant. Transplant course was complicated by Clostridium difficile infection, fevers, hypertension and thrombocytopenia, but he is stable 94 days post-transplantation. Conclusions Our case is the only living patient who has undergone successful BMT for a defect in the IFNγR2. We conclude that bone marrow transplantation for IFNγR2 deficiency is an effective means of correcting this immunodeficiency.