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Chronic granulomatous disease (CGD) is a rare immunodeficiency disorder characterized by a defective NADPH oxidase complex leading to an impaired respiratory burst and defective killing of pathogens by phagocytes. The most common type of CGD is caused by hemizygous mutations of the CYBB gene on the X chromosome encoding the gp91phox subunit. It usually affects males, yet heterozygous females may rarely manifest clinical signs of the disease due to skewed X chromosome inactivation in leukocytes . Despite advances in gene therapy, hematopoietic stem cell transplantation (HSCT) remains the main definitive treatment. Older patients, however, are at greater risk of HSCT-related complications and mortality and may require a specific approach.

D.C.V. is supported by the Fonds de la recherche en sante du Quebec clinician-scientist scholar Junior 2 program. L.D.N. and H.C.S. are supported by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases, National Institutes of Health. The Laboratory of Human Genetics of Infectious Diseases is supported by the Howard Hughes Medical Institute, the Rockefeller University, the St. Giles Foundation, the National Institutes of Health (NIH) (R01AI088364), the National Center for Advancing Translational Sciences (NCATS), NIH Clinical and Translational Science Award (CTSA) program (UL1 TR001866), a Fast Grant from Emergent Ventures, Mercatus Center at George Mason University, the Yale Center for Mendelian Genomics and the GSP Coordinating Center funded by the National Human Genome Research Institute (NHGRI) (UM1HG006504 and U24HG008956), the Fisher Center for Alzheimer’s Research Foundation, the Meyer Foundation, the French National Research Agency (ANR) under the “Investments for the Future” program (ANR-10-IAHU-01), the Integrative Biology of Emerging Infectious Diseases Laboratory of Excellence (ANR-10-LABX-62-IBEID), the French Foundation for Medical Research (FRM) (EQU201903007798), the FRM and ANR GENCOVID project, ANRS-COV05, the Square Foundation, Grandir - Fonds de solidarite pour l’enfance, the SCOR Corporate Foundation for Science, Institut National de la Sante et de la Recherche Medicale (INSERM), and the University of Paris. PB is supported by the MD-PhD program of the Imagine Institute (with the support of the Fondation Bettencourt-Schueller). I.M. is a Senior Clinical Investigator at the Research Foundation – Flanders, and is chair of the CSL Behring Chair of Primary Immunodeficiencies at KU Leuven, by the KU Leuven C1 Grant C16/18/007, by a VIB GC PID Grant, by the FWO Grants G0C8517N, G0B5120N, and G0E8420N, and by the Jeffrey Modell Foundation. This work is supported by ERN-RITA.

Cytokines play a major role in lymphoid development. Defects of the common gamma chain (gamma(c)) or of the JAK3 protein in humans have been shown to result in a severe combined immune deficiency (SCID), with a profound defect in T and natural killer (NK)-cell development, whereas B-cell generation is apparently unaffected (T-B+NK-SCID). While extensive molecular and biochemical analysis of these patients has been instrumental in understanding better the biological properties of the gamma(c) and JAK3 protein, an unexpected phenotypic heterogeneity of gamma(c) and JAK3 deficiency has emerged, indicating the need for appropriate and extensive investigations even in patients with atypical presentations. At the same time, characterization of the defects has been instrumental in the development of novel therapeutic approaches, from in utero hematopoietic stem cell transplantation to gene therapy.

Primary immunodeficiencies are intrinsic defects of immune systems. Mutations in a large number of cellular functions can lead to impaired immune responses. More than 80 primary immunodeficiencies are known to date. During the last years genes for several of these disorders have been identified. Here, mutation information for 23 genes affected in 14 immunodefects is presented. The proteins produced are employed in widely diverse functions, such as signal transduction, cell surface receptors, nucleotide metabolism, gene diversification, transcription factors, and phagocytosis. Altogether, the genetic defect of 2,140 families has been determined. Diseases with X-chromosomal origin constitute about 70% of all the cases, presumably due to full penetrance and because the single affected allele causes the phenotype. All types of mutations have been identified; missense mutations are the most common mutation type, and truncation is the most common effect on the protein level. Mutational hotspots in many disorders appear in CPG dinucleotides. The mutation data for the majority of diseases are distributed on the Internet with a special database management system, MUTbase. Despite large numbers of mutations, it has not been possible to make genotype-phenotype correlations for many of the diseases.

The outcome of high-risk (HR) Acute Lymphoblastic Leukemia (ALL) patients enrolled in AIEOP-BFM ALL 2000 study (NCT00613457) in Italy is described. Overall, 1999 Philadelphia negative ALL patients entered the study. HR criteria were: minimal residual disease (MRD) levels ≥10-3 at day 78 (HR-MRD), no complete remission (no-CR) at day 33, t(4;11) translocation, Prednisone Poor Response (PPR). Treatment (2 years) included protocol I, 3 polychemotherapy blocks, delayed intensification (protocol IIx2 or IIIx3), cranial radiotherapy, maintenance. 312 HR patients (15.6% of the total) had 5-year event-free survival (EFS) and overall survival (OS) of 58.9%(SE 2.8) and 68.9%(2.6). In hierarchical order, EFS was 45.9%(4.4) in 132 HR-MRD patients, 41.2%(11.9) in 17 patients no-CR at day 33, 36.4%(14.5) in 11 patients with t(4;11), 74.0%(3.6) in 152 HR patients only for PPR. No statistically significant difference was found for disease-free survival (DFS) in patients with very high risk features (HR-MRD, no-CR at day 33, t(4;11) translocation), given HSCT (n=66) or chemotherapy only (n=88), after adjusting for waiting time to hematopoietic stem cell transplantation (HSCT) (5.7 months). Patients at HR only for PPR have favorable outcome. High risk MRD is associated with poor outcome despite intensive treatment and/or HSCT and may qualify for innovative therapies. The study is registered at the US National Institutes of Health website http://clinicaltrials.gov as "Combination Chemotherapy Based on Risk of Relapse in Treating Young Patients With Acute Lymphoblastic Leukaemia" with the protocol identification number NCT00613457.

UNLABELLED This study reports the first paediatric case of acute inflammatory demyelinating polyradiculoneuropathy (AIDP) associated with a fatal haemophagocytic lymphohistiocytosis (HLH). The patient developed progressive weakness of the lower limbs in the context of a picture of infectious mononucleosis and Epstein-Barr virus (EBV) infection. After an apparent improvement, a fulminant hepatic failure and pancytopenia ensued, leading to death. Molecular genetic studies documented a compound heterozygosity for two mutations in the perforin (PRF1) gene as the background defect for a familial haemophagocytic lymphohistiocytosis (FHL). CONCLUSION In this patient EBV infection triggered both AIDP and FHL. The latter condition was due to PRF1 deficiency. Two novel mutations in the PRF1 gene were concomitantly present in the patient. The first caused an amino acid change, while the second introduced a stop codon in the sequence which resulted in a truncated protein.

Familial haemophagocytic lymphohistiocytosis (FHL) is a genetically heterogeneous disorder characterised by constitutive defects in cellular cytotoxicity resulting in fever, hepatosplenomegaly and cytopenia, and the outcome is fatal unless treated by chemoimmunotherapy followed by haematopoietic stem‐cell transplantation. Since 1999, mutations in the perforin gene giving rise to this disease have been identified; however, these account only for 40% of cases. Lack of a genetic marker hampers the diagnosis, suitability for transplantation, selection of familial donors, identification of carriers, genetic counselling and prenatal diagnosis. Mutations in the Munc13–4 gene have recently been described in patients with FHL. We sequenced the Munc13–4 gene in all patients with haemophagocytic lymphohistiocytosis not due to PRF1 mutations. In 15 of the 30 families studied, 12 novel and 4 known Munc13–4 mutations were found, spread throughout the gene. Among novel mutations, 2650C→T introduced a stop codon; 441del A, 532del C, 3082del C and 3226ins G caused a frameshift, and seven were mis sense mutations. Median age of diagnosis was 4 months, but six patients developed the disease after 5 years of age and one as a young adult of 18 years. Involvement of central nervous system was present in 9 of 15 patients, activity of natural killer cells was markedly reduced or absent in 13 of 13 tested patients. Chemo‐immunotherapy was effective in all patients. Munc13–4 mutations were found in 15 of 30 patients with FHL without PRF1 mutations. Because these patients may develop the disease during adolescence or even later, haematologists should include FHL2 and FHL3 in the differential diagnosis of young adults with fever, cytopenia, splenomegaly and hypercytokinaemia.

Background The number of patients with sickle cell disease (SCD) has increased in Italy in the past decade due to immigration. In spite of the established efficacy of hydroxyurea (HU) in childhood, population-based data regarding its prescription and effectiveness come mainly from studies performed in adults or outside Europe. Population and methods The Hydroxyurea in SCD: A Large Nation-wide Cohort Study from Italy was a retrospective cohort study of adult and pediatric patients with SCD attending 32 centers. Pediatric data are analyzed separately. Results Out of 504 children followed in 11 centers, 206 (40%) were on HU (194 SS/Sβ°, 12 SC/Ss+); 74% came from Sub-Saharian Africa and 18% from Europe. HU therapy indications for SS/Sβ° patients were as follows: 57% painful vaso-occlusive crisis, acute chest syndrome or both, 24% anemia, 8% anemia, and other reasons (the majority had Hb ≤ 8–8.5 g/dl, revealing scarce acceptance of low Hb values by pediatric hematologist). Mean starting dose was 15.5 mg/kg, and dose at full regimen was 17.1 mg/kg. Mean age at HU therapy was 7.68 years, although it was lower for SS/Sβ° patients. Only 10% started HU before 3 years. In 92%, 500 mg capsule was used; in 6%, the galenic was used; and in 2%, 100 mg tablet was used. Significant reduction of clinical events and inpatients admissions, with improvement in hematological parameters, was observed for SS/Sβ° patients and a trend toward improvement for SC/Ss+ patients was also observed. Conclusions HU effectiveness is demonstrated in a national cohort of children with SCD living in Italy, even at a lower dose than recommended, revealing good adherence to a treatment program by a socially vulnerable group of patients such as immigrants.

BACKGROUND:Adenosine deaminase (ADA) deficiency causes severe cellular and humoral immune defects and dysregulation because of metabolic toxicity. Alterations in B-cell development and function have been poorly studied. Enzyme replacement therapy (ERT) and hematopoietic stem cell (HSC) gene therapy (GT) are therapeutic options for patients lacking a suitable bone marrow (BM) transplant donor. OBJECTIVE: We sought to study alterations in B-cell development in ADA-deficient patients and investigate the ability of ERT and HSC-GT to restore normal B-cell differentiation and function. METHODS:Flow cytometry was used to characterize B-cell development in BM and the periphery. The percentage of gene-corrected B cells was measured by using quantitative PCR. B cells were assessed for their capacity to proliferate and release IgM after stimulation. RESULTS:Despite the severe peripheral B-cell lymphopenia, patients with ADA-deficient severe combined immunodeficiency showed a partial block in central BM development. Treatment with ERT or HSC-GT reverted most BM alterations, but ERT led to immature B-cell expansion. In the periphery transitional B cells accumulated under ERT, and the defect in maturation persisted long-term. HSC-GT led to a progressive improvement in B-cell numbers and development, along with increased levels of gene correction. The strongest selective advantage for ADA-transduced cells occurred at the transition from immature to naive cells. B-cell proliferative responses and differentiation to immunoglobulin secreting IgM after B-cell receptor and Toll-like receptor triggering were severely impaired after ERT and improved significantly after HSC-GT. CONCLUSIONS:ADA-deficient patients show specific defects in B-cell development and functions that are differently corrected after ERT and HSC-GT.

Adenosine deaminase-deficient severe combined immunodeficiency was the first disease investigated for gene therapy because of a postulated production or survival advantage for gene-corrected T lymphocytes, which may overcome inefficient gene transfer. Four years after three newborns with this disease were given infusions of transduced autologous umbilical cord blood CD34+ cells, the frequency of gene-containing T lymphocytes has risen to 1–10%, whereas the frequencies of other hematopoietic and lymphoid cells containing the gene remain at 0.01–0.1%. Cessation of polyethylene glycol-conjugated adenosine deaminase enzyme replacement in one subject led to a decline in immune function, despite the persistence of gene-containing T lymphocytes. Thus, despite the long-term engraftment of transduced stem cells and selective accumulation of gene-containing T lymphocytes, improved gene transfer and expression will be needed to attain a therapeutic effect.

A large proportion of Wiskott-Aldrich syndrome (WAS) patients develop autoimmunity and allergy. CD4(+)CD25(+)FOXP3(+) natural regulatory T (nTreg) cells play a key role in peripheral tolerance to prevent immune responses to self-antigens and allergens. Therefore, we investigated the effect of WAS protein (WASP) deficiency on the distribution and suppressor function of nTreg cells. In WAS(-/-) mice, the steady-state distribution and phenotype of nTreg cells in the thymus and spleen were normal. However, WAS(-/-) nTreg cells engrafted poorly in immunized mice, indicating perturbed homeostasis. Moreover, WAS(-/-) nTreg cells failed to proliferate and to produce transforming growth factor beta upon T cell receptor (TCR)/CD28 triggering. WASP-dependent F-actin polarization to the site of TCR triggering might not be involved in WAS(-/-) nTreg cell defects because this process was also inefficient in wild-type (WT) nTreg cells. Compared with WT nTreg cells, WAS(-/-) nTreg cells showed reduced in vitro suppressor activity on both WT and WAS(-/-) effector T cells. Similarly, peripheral nTreg cells were present at normal levels in WAS patients but failed to suppress proliferation of autologous and allogeneic CD4(+) effector T cells in vitro. Thus, WASP appears to play an important role in the activation and suppressor function of nTreg cells, and a dysfunction or incorrect localization of nTreg cells may contribute to the development of autoimmunity in WAS patients. A large proportion of Wiskott-Aldrich syndrome (WAS) patients develop autoimmunity and allergy. CD4(+)CD25(+)FOXP3(+) natural regulatory T (nTreg) cells play a key role in peripheral tolerance to prevent immune responses to self-antigens and allergens. Therefore, we investigated the effect of WAS protein (WASP) deficiency on the distribution and suppressor function of nTreg cells. In WAS(-/-) mice, the steady-state distribution and phenotype of nTreg cells in the thymus and spleen were normal. However, WAS(-/-) nTreg cells engrafted poorly in immunized mice, indicating perturbed homeostasis. Moreover, WAS(-/-) nTreg cells failed to proliferate and to produce transforming growth factor beta upon T cell receptor (TCR)/CD28 triggering. WASP-dependent F-actin polarization to the site of TCR triggering might not be involved in WAS(-/-) nTreg cell defects because this process was also inefficient in wild-type (WT) nTreg cells. Compared with WT nTreg cells, WAS(-/-) nTreg cells showed reduced in vitro suppressor activity on both WT and WAS(-/-) effector T cells. Similarly, peripheral nTreg cells were present at normal levels in WAS patients but failed to suppress proliferation of autologous and allogeneic CD4(+) effector T cells in vitro. Thus, WASP appears to play an important role in the activation and suppressor function of nTreg cells, and a dysfunction or incorrect localization of nTreg cells may contribute to the development of autoimmunity in WAS patients

To investigate paediatricians' perception and awareness of off-label (OL) and unlicensed drug usage in clinical practice.We conducted a questionnaire-based, observational study involving 28 departments/specialty units of four tertiary paediatrics Italian hospitals. The questionnaire was sent to a designated paediatrician in each department/specialty unit with the request that they summarise their awareness of OL prescriptions after a group discussion with all paediatricians working in the same department/unit.A total of 95 drugs were identified. The most common perceived reasons detected for OL use were age and formulation. Corticosteroids, ACE-inhibitors, beta-blockers and calcium-antagonists were most frequently indicated as OL for formulation, while ACE-inhibitors, new generation anti-epilepsy drugs, immunosuppressants, ketorolac and propofol as OL for age. Adrenaline, midazolam and ACE-inhibitors were indicated as unlicensed for route of administration. We found a high concordance between the OL drugs identified by physicians and those reported in the "Italian Summary Product Characteristics".Italian paediatricians perceived different drugs as unlicensed/OL from those identified by existing prescriptions studies. These perceived drugs may represent a priority in tackling the problem of OL usage in the hospital practice. The review of the Italian Summary Product Characteristics of some of the drugs identified, together with the monitoring of permanent clinical practice and with new clinical research, may be a step forward to reduce OL use in children.

Wiskott-Aldrich syndrome (WAS) protein (WASP) plays a key role in TCR-mediated activation and immunological synapse formation. However, the effects of WASP deficiency on effector functions of human CD4+ and CD8+ T cells remain to be determined. In this study, we report that TCR/CD28-driven proliferation and secretion of IL-2, IFN-γ, and TNF-α are strongly reduced in CD8+ T cells from WAS patients, compared with healthy donor CD8+ T cells. Furthermore, WAS CD4+ T cells secrete low levels of IL-2 and fail to produce IFN-γ and TNF-α, while the production of IL-4, IL-5, and IL-10 is only minimally affected. Defective IL-2 and IFN-γ production persists after culture of naive WAS CD4+ T cells in Th1-polarizing conditions. The defect in Th1 cytokine production by WAS CD4+ and CD8+ T cells is also present at the transcriptional level, as shown by reduced IL-2 and IFN-γ mRNA transcripts after TCR/CD28 triggering. The reduced transcription of Th1 cytokine genes in WAS CD4+ T cells is associated with a defective induction of T-bet mRNA and a reduction in the early nuclear recruitment of NFAT-1, while the defective activation of WAS CD8+ T cells correlates with reduced nuclear recruitment of both NFAT-1 and NFAT-2. Together, our data indicate that WASP regulates the transcriptional activation of T cells and is required specifically for Th1 cytokine production.