ST2 and Reg3α: Can they predict aGvHD, steroid refractoriness and transplant-related mortality in pediatric patients after HSCT?

BACKGROUND/AIM: There are several complications of hematopoietic stem cell transplantation. Without any doubt, most important of these is aGvHD that increases transplant-related mortality. The aim of this study is to investigate whether ST-2 and Reg3α levels measured at an early stage in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation can be individual biomarkers identifying future GvHD and predicting treatment response. MATERIALS AND METHODS: From January 2019 to January 2021, 27 patients undergoing hematopoietic stem cell transplantation for primary immunodeficiency or hematopoietic diseases formed the study group. During their follow-up, the patients were classified into two groups as those developing and those not developing aGvHD. Nineteen healthy volunteers from a similar age group who needed their blood samples drawn for other reasons and who did not have any history of chronic disease, infection or medication use formed the control group. Blood samples of patients scheduled to have allogeneic HSCT were obtained before the administration of the preparative regimen, on Day +7 post-transplant and on the day of diagnosis if they developed aGvHD. Serum samples were stored at -20ºC until the day of processing. ST2 and Reg3α levels were measured using the ELISA method. RESULTS: For patients who developed aGvHD (n = 13), ST2 levels obtained before the transplantation, on Day +7 post-transplant and on the day of aGvHD diagnosis (in patients developing GvHD) were significantly higher compared to the healthy Control Group (p-value <0.05). As regards to the samples obtained on the same days, ST2 levels did not differ significantly among patients who developed and those who did not develop GvHD (n = 14; p-value >0.05). ST2 levels of samples obtained on the days that acute skin and gastrointestinal tract GvHD developed did not differ significantly between these two groups (p-value >0.05). Reg3α levels of the pre-transplant samples, on Day +7 after the transplantation and on the day of aGvHD diagnosis did not show any difference between any of the groups (p-value >0.05). As only two patients died after transplantation, thus correlation of ST2 and Reg3α levels with transplant-related mortality could not be proven. CONCLUSION: The results of this study suggest that ST2 and Reg3α levels are neither diagnostic nor prognostic or predictive biomarkers of aGvHD, steroid resistance or transplant-related mortality in pediatric patients. This study can be regarded as a pilot study because of the small patient population; more research involving a larger patient population is required.

Junctional Epidermolysis Bullosa Linked to Homozygous Mutation in LAMC2 Gene: A Case Report With Eosinophil-Rich Inflammatory Infiltrate.

ABSTRACT: Junctional epidermolysis bullosa (JEB) is a rare, incurable, devastating, and mostly fatal congenital genetic disorder characterized by painful blistering of the skin and mucous membranes in response to minor trauma or pressure. JEB is classified roughly into 2 subtypes: JEB-Herlitz is caused by mutations on genes encoding laminin-332. The authors present a patient consulted with a suspicion of primary immunodeficiency due to skin sores that started at the age of 1 month and a history of 3 siblings who died with similar sores, who was diagnosed with JEB-Herlitz after detecting a homozygous LAMC2 gene mutation in WES analysis. Microscopic evaluation of hematoxylin and eosin-stained sections showed vesicle formation with subepidermal separation, which is accompanied by striking neutrophil and eosinophil leukocyte infiltration both in the vesicle and papillary dermis (eosinophil-rich inflammatory infiltrate). Such a histopathological finding has been rarely reported in this condition.

Defective Treg generation and increased type 3 immune response in leukocyte adhesion deficiency 1.

In 15 Turkish LAD-1 patients and controls, we assessed the impact of pathogenic ITGB2 mutations on Th17/Treg differentiation and functions, and innate lymphoid cell (ILC) subsets. The percentage of peripheral blood Treg cells, in vitro-generated induced Tregs differentiated from naive CD4+ T cells were decreased despite the elevated absolute counts of CD4+ cells in LAD-1 patients. Serum IL-23 levels were elevated in LAD-1 patients. Post-curdlan stimulation, LAD-1 patient-derived PBMCs produced more IL-17A. Additionally, the percentages of CD18-deficient Th17 cells expanded from total or naïve CD4+ T cells were higher. The blood ILC3 subset was significantly elevated in LAD-1. Finally, LAD-1 PBMCs showed defects in trans-well migration and proliferation and were more resistant to apoptosis. Defects in de novo generation of Tregs from CD18-deficient naïve T cells and elevated Th17s, and ILC3s in LAD-1 patients' peripheral blood suggest a type 3-skewed immunity and may contribute to LAD-1-associated autoimmune symptoms.

Evaluation of thymopoiesis in healthy Turkish children aged 0-6 years.

BACKGROUND: Early diagnosis and effective treatment serve as life-saving procedures for primary immunodeficiencies (PIDs) which are very common and a major public health problem in Turkey. Severe combined immunodeficiency (SCID) is constitutively a T-cell defect in which naïve T-cell development is defective due to the mutations in genes responsible for the T cell differentiation and insufficient thymopoiesis. So, assessment of thymopoiesis is very important in the diagnosis of SCID and several combined immune deficiencies (CIDs). METHODS: The purpose of this study is to examine thymopoiesis in healthy children via measurement of recent thymic emigrants (RTE); T lymphocytes that express CD4, CD45RA and CD31 to establish the RTE reference values in Turkish children. RTE were measured in the peripheral blood (PB) of 120 healthy infants and children between 0-6 years including cord blood samples, by flow cytometry. RESULTS: The absolute count of RTE cells and their relative ratios were found to be higher during the first year of life, being highest at the 6th month and tending to decrease significantly by age following birth (p=0.001). In the cord blood group, both values were lower than those in the 6-month-old group. The absolute lymphocyte count (ALC) varying by age, was found to reduce to 1850/mm³ in 4-years and after. CONCLUSIONS: Here we evaluated normal thymopoiesis and established the normal reference levels of RTE cells in the peripheral blood of healthy children aged between 0-6 years. We believe that the collected data will contribute to early diagnosis and monitoring of immune reconstitution; serving as an additional fast and reliable marker for many PID patients especially for SCID including many other CIDs, especially in nations where newborn screening (NBS) via T cell receptor excision circles (TREC) has not yet become available.

The Determining Factors for Outcome of Pediatric Intensive Care Admitted Children After Stem Cell Transplantation.

INTRODUCTION: Requiring pediatric intensive care unit (PICU) admission relates to high mortality and morbidity in patients who received hematopoietic stem cell transplantation (HSCT). In this study, we aimed to evaluate the indications for PICU admission, treatments, and the determining risk factors for morbidity and mortality in patients who had allogeneic HSCT from various donors. MATERIALS AND METHODS: In this retrospective study, we enrolled to patients who required the PICU after receiving allogeneic HSCT at our Pediatric Bone Marrow Transplantation Unit between 2005 and 2020. We evaluated to indication to PICU admission, applications, mortality rate, and the determining factors to outcomes. RESULTS: Thirty-three (7%) patients had 47 PICU admissions and 471 patients underwent bone marrow transplantation during 16-year study period. Also, 14 repeated episodes were registered in 9 different patients. The median age of PICU admitted patients was 4 (0.3 to 18) years and 29 (62%) were male. The main reasons for PICU admission were a respiratory failure, sepsis, and neurological event in 20, 8, and 7 patients, respectively. The average length of PICU stay was 14.5 (1 to 80) days, 14 (43%) of patients survived and the mortality rate was 57%. Multiple organ failure ( P =0.001), need for respiratory support ( P =0.007), inotrope agents ( P =0.001), and renal replacement therapy ( P =0.013) were found as significant risk factors for mortality. CONCLUSIONS: Allogeneic HSCT recipients need PICU admission because of its related different life-threatening complications. But there is a good chance of survival with quality PICU care and different advanced organ support methods.

The Middle East and North Africa Diagnosis and Management Guidelines for Inborn Errors of Immunity.

Human inborn errors of immunity (IEI) are a group of 485 distinct genetic disorders affecting children and adults. Signs and symptoms of IEI are heterogeneous, and accurate diagnosis can be challenging and depends on the available human expertise and laboratory resources. The Middle East and North Africa (MENA) region has an increased prevalence of IEI because of the high rate of consanguinity with a predominance of autosomal recessive disorders. This area also exhibits more severe disease phenotypes compared with other regions, probably due to the delay in diagnosis. The MENA-IEI registry network has designed protocols and guidelines for the diagnosis and treatment of IEI, taking into consideration the variable regional expertise and resources. These guidelines are primarily meant to improve the care of patients within the region, but can also be followed in other regions with similar patient populations.

Pediatric Invasive Aspergillosis: a Retrospective Review of 59 Cases.

Invasive aspergillosis (IA) is a major cause of morbidity and mortality. This study aimed to present our 10-year IA experience at a single center. Fifty-nine pediatric patients with IA were included in this study. The male-to-female ratio was 42/17. The median age was 8.75 years. Hematologic malignancy was present in the majority of the patients (40/59, 68%). The mean neutropenia duration was 18.5 days. Cytosine arabinoside was the most common immunosuppressive therapy directed at T cells during IA diagnosis. IA cases were categorized as proven (27%), probable (51%), or possible (22%) according to the 2008 European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) criteria. The lungs (78%) were the most common site of IA, and nodules were the most frequent radiological findings (75.5%). In 38 patients (64.4%) receiving antifungal prophylaxis, prophylactic agents included fluconazole (30.5%), liposomal amphotericin B (23.7%), posaconazole (8.5%), and voriconazole (1.7%). Initial treatment was most commonly administered as monotherapy (69.5%). The median antifungal treatment duration was 67 days. Eleven deaths (18.6%) were due to aspergillosis. With the increased use of corticosteroids, biological agents, and intensive immunosuppressive chemotherapy, IA will most likely continue to occur frequently in pediatric patients.

Effect of CD34⁺ Total/Myeloid CD34⁺ Cell Progenitors and B-Lymphoid Progenitors Within the Bone Marrow Grafts on the Hematopoietic Recovery After Hematopoietic Stem Cell Transplantation.

OBJECTIVES: The influence of CD34⁺ cells on transplant outcomes following hematopoietic stem cell transplantation remains controversial. A minimum of 2.0 to 2.5 million CD34⁺ cells/kg of patient weight is requested for a rapid and durable engraftment. The aim of this study was to detect the ratio of CD34+ B-lymphoid progenitors (hematogones) in bone marrow grafts and investigate their effects on hematopoietic recovery after transplant. MATERIALS AND METHODS: Our study included 41 patients who received a bone marrow graft from their HLA-matched donor from 2016 through 2019. The CD34⁺ cell numbers within the graft were detected using Stem-Kit (Beckman Coulter). The ratio of CD34⁺ hematogones was determined either by their light scatter characteristics or by the detection of CD34, CD19, or CD10 coexpressing cells in a separate tube. RESULTS: The median number of CD34⁺ cells was 5.9 × 106/kg (0.8-14.3 × 106/kg). The CD34⁺ cells consisted of 71% (range, 35.7%-100%) and 29% (range, 5.7%-64.3%) myeloid and B-lymphoid progenitors, respectively. Percentage of CD34⁺ (P < .001) and total (P < .001) hematogones in correlation with donor age. Time of neutrophil engraftment was significantly longer (P = .039) when total infused CD34⁺ cell content was <3 × 106/kg. CONCLUSIONS: A remarkable population of hematogones within the CD34⁺ cell pool was detected in bone marrow grafts. Detection of the ratio of hematogones and most primitive stem cells (CD34⁺CD90⁺CD38⁻) may overall provide more information to build a better correlation between CD34⁺ cell content and the recovery of bone marrow.

Scales of Magt1 Gene: Novel Mutations, Different Presentations.

Loss-of-function mutations in magnesium transporter 1 (MAGT1) gene cause X-linked magnesium deficiency with Epstein-Barr virus (EBV) infection and neoplasm (X-MEN), a disease with quite diverse clinical and immunological consequences. The phenotypic characteristics of the initially described patients included CD4+ T cell lymphopenia, immune deficiency, EBV viremia, and EBV-related lymphoproliferative disease. To date, a total of 25 patients have been reported. The spectrum of the MAGT1 defect ranges from other viral infections (HSV, VZV, CMV, MCV) and sinopulmonary bacterial infections, autoimmune diseases, non-EBV driven lymphoproliferative disease, Castleman disease, HHV8+ Kaposi's sarcoma, vasculitis (Kawasaki) to glycosylation defects in new patients. Here, we report 2 patients from two different families with novel MAGT1 mutations and different clinical features. The first patient presented with B cell lymphoma and low IgM level without recurrent infections. The second patient presented with recurrent upper respiratory tract infections, Kawasaki-like disease, hypogammaglobulinemia, and T cell lymphopenia. X-MEN disease is the first phenotype identified due to MAGT1 mutation. The identification of new mutations and atypical presentations will clarify whether there is a relationship between the genotype and the phenotype and the characteristics of the disease.

Effects of Umbilical Cord Management Strategies on Stem Cell Transfusion, Delivery Room Adaptation, and Cerebral Oxygenation in Term and Late Preterm Infants.

Background: The umbilical cord blood contains a high concentration of stem cells. There is not any published study evaluating the amount of stem cells that have the potential to be transferred to the infant through placental transfusion methods as delayed cord clamping (DCC) and umbilical cord milking (UCM). The aim of this study is to measure the concentrations of endothelial progenitor cell (EPC) and CD34+ hematopoietic stem cell (HSC) in the placental residual blood volume (PRBV), and evaluate the delivery room adaptation and cerebral oxygenation of these infants. Methods: Infants with ≥36 gestational weeks were randomized to receive DCC (120 s), UCM, or immediate cord clamping (ICC). EPC and CD34+ HSC were measured by flow cytometry from the cord blood. PRBV was collected in the setup. The cord blood gas analysis and complete blood count were performed. The heart rate (HR), oxygen saturation (SpO2), and cerebral regional oxygen saturation (crSO2) were recorded. Results: A total of 103 infants were evaluated. The amount of PRBV (in ml and ml/kg) was higher in the ICC group (p < 0.001). The number of EPCs in the PRBV content (both ml and ml/kg) were the highest in the ICC group (p = 0.002 and p = 0.001, respectively). The number of CD34+ HSCs in PRBV content (ml and ml/kg) was similar in all groups, but nonsignificantly higher in the ICC group. The APGAR scores at the first and fifth min were lower in the ICC group (p < 0.05). The mean crSO2 values were higher at the 3rd and 10th min in the DCC group (p = 0.042 and p = 0.045, respectively). cFOE values were higher at the 3rd and 10th min in the ICC group (p = 0.011 and p < 0.001, respectively). Conclusion: This study showed that placental transfusion methods, such as DCC and UCM, provide both higher blood volume, more stem cells transfer to the infant, and better cerebral oxygenation in the first minutes of life, whereas many lineages of stem cells is lost to the placenta by ICC with higher residual blood volume. These cord management methods rather than ICC do not require any cost or technology, and may be a preemptive therapeutic source for diseases of the neonatal period.

The role of galactomannan test results in the diagnosis of pediatric invasive aspergillosis.

BACKGROUND: Invasive aspergillosis (IA) is an important cause of morbidity and mortality in immunosuppressed children. Early detection of the infection can improve prognosis in this patient population. OBJECTIVES: To investigate the utility of Aspergillus galactomannan antigen assay (GM-EIA) as a diagnostic tool for IA in at-risk paediatric patients. PATIENTS/METHODS: For the study, 659 GM-EIA results from 59 patients diagnosed with IA and 3368 GM-EIA results from 351 subjects without evidence for IA (controls) were reviewed retrospectively. Three cut-off values (i.e. ≥0.5, ≥1, ≥1.5) were specified to determine GM-EIA positivity. RESULTS: The median age was 6.3 years for boys and 14.5 years for girls. There was a significant difference between the girls and boys in terms of age (p < 0.01). For proven/probable/possible IA patients, sensitivity of 67.8% and specificity of 59.8% were detected when the ≥0.5 cut-off value was used for GM-EIA-positivity. The specificity increased to 80% at the cut-off of ≥1 and to 88% at the cut-off of ≥1.5. False positivity rates were 9.14, 3, and 1.45% at the ≥0.5, ≥1 and ≥1.5 cut-offs respectively. In the proven/probable IA group, sensitivity and negative predictive values were 86.9 and 97.2% at the ≥0.5 cut-off, 85.7 and 97.9%, at the ≥1 cut-off and 84.2 and 98.1% at ≥1.5 cut-off respectively. The positive likelihood ratio was 7.57 and the odds ratio was 42.67 at ≥1.5 cut-off. CONCLUSION: The GM-EIA may be used for both screening and diagnostic purposes in paediatric patients using a cut-off value of ≥1.5 for GM-EIA positivity.

Primary antibody deficiencies in Turkey: molecular and clinical aspects.

Primary antibody deficiencies (PAD) are the most common subtype of primary immunodeficiencies, characterized by increased susceptibility to infections and autoimmunity, allergy, or malignancy predisposition. PAD syndromes comprise of immune system genes highlighted the key role of B cell activation, proliferation, migration, somatic hypermutation, or isotype switching have a wide spectrum from agammaglobulinemia to selective Ig deficiency. In this study, we describe the molecular and the clinical aspects of fifty-two PAD patients. The most common symptoms of our cohort were upper and lower respiratory infections, bronchiectasis, diarrhea, and recurrent fever. Almost all patients (98%) had at least one of the symptoms like autoimmunity, lymphoproliferation, allergy, or gastrointestinal disease. A custom-made next-generation sequencing (NGS) panel, which contains 24 genes, was designed to identify well-known disease-causing variants in our cohort. We identified eight variants (15.4%) among 52 PAD patients. The variants mapped to BTK (n = 4), CD40L (n = 1), ICOS (n = 1), IGHM (n = 1), and TCF3 (n = 1) genes. Three novel variants were described in the BTK (p.G414W), ICOS (p.G60*), and IGHM (p.S19*) genes. We performed Sanger sequencing to validate pathogenic variants and check for allelic segregation in the family. Targeted NGS panel sequencing can be beneficial as a suitable diagnostic modality for diagnosing well-known monogenic PAD diseases (only 2-10% of PADs); however, screening only the coding regions of the genome may not be adequately powered to solve the pathogenesis of PAD in all cases. Deciphering the regulatory regions of the genome and better understanding the epigenetic modifications will elucidate the molecular basis of complex PADs.

Impaired respiratory burst contributes to infections in PKCδ-deficient patients.

Patients with autosomal recessive protein kinase C δ (PKCδ) deficiency suffer from childhood-onset autoimmunity, including systemic lupus erythematosus. They also suffer from recurrent infections that overlap with those seen in patients with chronic granulomatous disease (CGD), a disease caused by defects of the phagocyte NADPH oxidase and a lack of reactive oxygen species (ROS) production. We studied an international cohort of 17 PKCδ-deficient patients and found that their EBV-B cells and monocyte-derived phagocytes produced only small amounts of ROS and did not phosphorylate p40phox normally after PMA or opsonized Staphylococcus aureus stimulation. Moreover, the patients' circulating phagocytes displayed abnormally low levels of ROS production and markedly reduced neutrophil extracellular trap formation, altogether suggesting a role for PKCδ in activation of the NADPH oxidase complex. Our findings thus show that patients with PKCδ deficiency have impaired NADPH oxidase activity in various myeloid subsets, which may contribute to their CGD-like infectious phenotype.

Single-Center Study of 72 Patients with Severe Combined Immunodeficiency: Clinical and Laboratory Features and Outcomes.

Severe combined immunodeficiency is an inborn error of immunity characterized by impairments in the numbers and functions of T and B lymphocytes due to various genetic causes, and if it remains untreated, patients succumb to infections during the first 2 years of life. PURPOSE AND METHODS: This study reported retrospective data from 72 infants diagnosed with SCID including their major clinical features, HSCT characteristics, and outcomes over a 20-year period (1997-2017). RESULTS: Sixty-one of 72 SCID patients in the study underwent HSCT from 1997 to 2017. Median ages at the time of diagnosis and transplantation were 3.5 months and 5 months, respectively. Consanguinity was present in 68% of the patients, and T - B - NK + phenotype was predominantly identified. The overall survival was 80.3% over a 20-year period. However, the patients transplanted during an active infection had a lower survival rate of 73.9% compared to 100% for patients transplanted infection-free or with a previous infection that had resolved. The survival rate was significantly higher among recipients of HLA-identical transplants (92.9%), compared to recipients of mismatched related transplants (70%). The overall survival increased from 50 (1997-2006) to 85% (2007-2017) during the last 10 years. CONCLUSIONS: This is one of the largest single-center studies in Turkey with extensive experience about SCID patients. Early diagnosis of SCID patients before the onset of an infection and early transplantation are shown to be extremely important factors affecting the outcome and increasing the survival regardless of the donor type based on the results of this study.

Expanding the Nude SCID/CID Phenotype Associated with FOXN1 Homozygous, Compound Heterozygous, or Heterozygous Mutations.

Human nude SCID is a rare autosomal recessive inborn error of immunity (IEI) characterized by congenital athymia, alopecia, and nail dystrophy. Few cases have been reported to date. However, the recent introduction of newborn screening for IEIs and high-throughput sequencing has led to the identification of novel and atypical cases. Moreover, immunological alterations have been recently described in patients carrying heterozygous mutations. The aim of this paper is to describe the extended phenotype associated with FOXN1 homozygous, compound heterozygous, or heterozygous mutations. We collected clinical and laboratory information of a cohort of 11 homozygous, 2 compound heterozygous, and 5 heterozygous patients with recurrent severe infections. All, except one heterozygous patient, had signs of CID or SCID. Nail dystrophy and alopecia, that represent the hallmarks of the syndrome, were not always present, while almost 50% of the patients developed Omenn syndrome. One patient with hypomorphic compound heterozygous mutations had a late-onset atypical phenotype. A SCID-like phenotype was observed in 4 heterozygous patients coming from the same family. A spectrum of clinical manifestations may be associated with different mutations. The severity of the clinical phenotype likely depends on the amount of residual activity of the gene product, as previously observed for other SCID-related genes. The severity of the manifestations in this heterozygous family may suggest a mechanism of negative dominance of the specific mutation or the presence of additional mutations in noncoding regions.

Clinical Features and Outcomes of 23 Patients with Wiskott-Aldrich Syndrome: A Single-Center Experience

Objective: Wiskott-Aldrich syndrome (WAS) is an X-linked primary immune deficiency characterized by microthrombocytopenia, eczema, and recurrent infections. We aimed to evaluate the clinical features and outcomes of a WAS cohort. Materials and Methods: We retrospectively evaluated the clinical courses, immunological features, treatments, and outcomes in a total of 23 WAS patients together with data related to 11 transplanted cases among them between 1982 and 2019. Results: Before admission, 11 patients (48%) were misdiagnosed with immune thrombocytopenia. WAS scores were mostly 4 or 5. Eleven patients were transplanted and they had an overall survival rate of 100% during a median follow-up period of 8.5 years (range: 8 months to 20 years). Five patients who were not transplanted died at a median of 7 years (range: 2-26 years). Nontransplanted patients had high morbidity due to organ damage, mostly caused by autoimmunity, bleeding, and infections. Two novel mutations were also defined. Conclusion: All male babies with microthrombocytopenia should be evaluated for WAS. Hematopoietic stem cell transplantation should be performed at the earliest age with the best possible donors.

Extended clinical and immunological phenotype and transplant outcome in CD27 and CD70 deficiency.

Biallelic mutations in the genes encoding CD27 or its ligand CD70 underlie inborn errors of immunity (IEIs) characterized predominantly by Epstein-Barr virus (EBV)-associated immune dysregulation, such as chronic viremia, severe infectious mononucleosis, hemophagocytic lymphohistiocytosis (HLH), lymphoproliferation, and malignancy. A comprehensive understanding of the natural history, immune characteristics, and transplant outcomes has remained elusive. Here, in a multi-institutional global collaboration, we collected the clinical information of 49 patients from 29 families (CD27, n = 33; CD70, n = 16), including 24 previously unreported individuals and identified a total of 16 distinct mutations in CD27, and 8 in CD70, respectively. The majority of patients (90%) were EBV+ at diagnosis, but only ∼30% presented with infectious mononucleosis. Lymphoproliferation and lymphoma were the main clinical manifestations (70% and 43%, respectively), and 9 of the CD27-deficient patients developed HLH. Twenty-one patients (43%) developed autoinflammatory features including uveitis, arthritis, and periodic fever. Detailed immunological characterization revealed aberrant generation of memory B and T cells, including a paucity of EBV-specific T cells, and impaired effector function of CD8+ T cells, thereby providing mechanistic insight into cellular defects underpinning the clinical features of disrupted CD27/CD70 signaling. Nineteen patients underwent allogeneic hematopoietic stem cell transplantation (HSCT) prior to adulthood predominantly because of lymphoma, with 95% survival without disease recurrence. Our data highlight the marked predisposition to lymphoma of both CD27- and CD70-deficient patients. The excellent outcome after HSCT supports the timely implementation of this treatment modality particularly in patients presenting with malignant transformation to lymphoma.