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Background Activated phosphatidylinositol-3-OH kinase δ syndrome type 1 (APDS1) is a recently described primary immunodeficiency syndrome characterized by recurrent respiratory tract infections, lymphoid hyperplasia, and Herpesviridae infections caused by germline gain-of-function mutations of PIK3CD. Hematopoietic stem cell transplantation (HSCT) can be considered to ameliorate progressive immunodeficiency and associated malignancy, but appropriate indications, methods, and outcomes of HSCT for APDS1 remain undefined. Objective Our objective was to analyze the clinical manifestations, laboratory findings, prognosis, and treatment of APDS1 and explore appropriate indications and methods of HSCT. Methods We reviewed retrospectively the medical records of cohorts undergoing HSCT at collaborating facilities. Results Thirty-year overall survival was 86.1%, but event-free survival was 39.6%. Life-threatening events, such as severe infections or lymphoproliferation, were frequent in childhood and adolescence and were common indications for HSCT. Nine patients underwent HSCT with fludarabine-based reduced-intensity conditioning. Seven patients survived after frequent adverse complications and engraftment failure. Most symptoms improved after HSCT. Conclusion Patients with APDS1 showed variable clinical manifestations. Life-threatening progressive combined immunodeficiency and massive lymphoproliferation were common indications for HSCT. Fludarabine-based reduced-intensity conditioning–HSCT ameliorated clinical symptoms, but transplantation-related complications were frequent, including graft failure.

In an Aicardi-Goutieres syndrome patient, cimetidine successfully controlled periodic fever with improved serum autoimmune marker levels, suggesting the presence of crosstalk between autoinflammation and autoimmunity in type I interferonopathy.

Background The long-term outcome of X-linked hyper-IgM syndrome (XHIM) caused by mutations in CD40LG is poor, and the only curative treatment is hematopoietic stem cell transplantation (HSCT). Objective We sought to determine the clinical features and factors affecting outcomes in patients with XHIM. Methods We enrolled and retrospectively analyzed data from 56 Japanese patients with XHIM, including 29 patients who received HSCT. Results The long-term survival rate was poor in those not undergoing HSCT (overall survival rate at 40 years of age, 28.2%). The overall survival rate of patients undergoing HSCT (n = 29) was significantly higher than that of those not undergoing HSCT (n = 27, P = .0231). Moreover, event-free and disease-free survival rates were significantly greater in patients 5 years old or younger at the time of transplantation (n = 14) than in older patients (n = 15). Conclusion On the basis of these results, we concluded that HSCT improved the outcomes of patients with XHIM and that an age of 5 years or younger was optimal for the timing of HSCT because persistent infections and severe organ damage were frequently observed in patients older than 6 years.

Background Activated phosphatidylinositol 3-kinase δ syndrome (APDS) is a recently discovered primary immunodeficiency disease (PID). Excess phosphatidylinositol 3-kinase (PI3K) activity linked to mutations in 2 PI3K genes, PIK3CD and PIK3R1, causes APDS through hyperphosphorylation of AKT, mammalian target of rapamycin (mTOR), and S6. Objective This study aimed to identify novel genes responsible for APDS. Methods Whole-exome sequencing was performed in Japanese patients with PIDs. Immunophenotype was assessed through flow cytometry. Hyperphosphorylation of AKT, mTOR, and S6 in lymphocytes was examined through immunoblotting, flow cytometry, and multiplex assays. Results We identified heterozygous mutations of phosphatase and tensin homolog (PTEN) in patients with PIDs. Immunoblotting and quantitative PCR analyses indicated that PTEN expression was decreased in these patients. Patients with PTEN mutations and those with PIK3CD mutations, including a novel E525A mutation, were further analyzed. The clinical symptoms and immunologic defects of patients with PTEN mutations, including lymphocytic AKT, mTOR, and S6 hyperphosphorylation, resemble those of patients with APDS. Because PTEN is known to suppress the PI3K pathway, it is likely that defective PTEN results in activation of the PI3K pathway. Conclusion PTEN loss-of-function mutations can cause APDS-like immunodeficiency because of aberrant PI3K pathway activation in lymphocytes.