Activated PI3 Kinase Delta Syndrome: From Diagnostic to Therapy, A Case Report

Introduction: Activated phosphoinositide 3-kinase d syndrome (APDS) is an autosomal dominant primary immunodeficiency caused by gain of-function (GOF) mutations in PIK3CD. Activating mutations causing senescent T cells, lymphadenopathy, and immunodeficiency.

Case report: A 5-year-old boy without consanguinity and inbreeding. With a history of bicytopenia from the first month of life, BCGitis symptoms at 3 months and repeated airway infections. At the age of five, he presented with epistaxis and pneumonia due to opportunistic microorganisms. With suspicion of inborn error of immunity, high serum immunoglobulin-M level and inverted CD4+/CD8+ ratio.
The whole exome sequencing confirmed PIK3CD, activated phosphoinositide 3-kinase δ síndrome was diagnosed. Due to the presence of bilateral axillary and submandibular adenopathies, an oncological process was ruled out and a lymphoproliferative process secondary to citomegalovirus.
With indication of hematopoietic progenitor transplant, allogeneic model, resulting in a 100% compatible sibling, with a major ABO incompatibility (patient O +, donor A +). Intermediate risk for CMV (patient +, donor +). myeloablative conditioning regimen with busulfan (4.9mgkgday) and cyclophosphamide (60mgm2scday) was administered. With myeloid graft data on day 13 pos trasplant with a chimerism of 95%. No reported post-transplant complications. During follow-up, he continued with prophylaxis treatment with valganciclovir, itraconazole, ciprofloxacin, and administration of replacement gammaglobulin. GVHD prophylaxis with cyclosporine was administered until day 60 postrasplant. Clinically, there were no data on underlying disease activity or graft-versus-host disease; at follow-up without lymphadenopathy or evidence of lymphoproliferative syndrome and continues with CMV PCR negative. With presence of stable chimerism.

Conclusions: Treatments for APDS including conventional immunodeficiency therapies such as immunoglobulin replacement, antibiotic prophylaxis, and hematopoietic stem cell transplant. The patient is in good condiion with a good quality of life.

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