Minimum effective betamethasone dosage on the neurological phenotype in patients with ataxia-telangiectasia: a multicenter observer-blind study.

BACKGROUND AND PURPOSE: Ataxia-telangiectasia (A-T) is a rare neurodegenerative disease, due to A-T mutated (ATM) gene mutations, which typically presents with signs of progressive neurological dysfunction, cerebellar ataxia and uncoordinated movements. A-T severely affects patients' quality of life. Successful treatment options are still not available. The aim of this multicenter study, performed with a blind evaluation procedure, was to define the minimal effective dosage of oral betamethasone, thus preventing the occurrence of side effects. METHODS: Nine A-T patients were enrolled to receive betamethasone at increasing dosages of 0.001, 0.005 and 0.01 mg/kg/day. Neurological assessment and the evaluation of quality of life were performed through the Scale for the Assessment and Rating of Ataxia and the Italian version of the Childhood Health Assessment Questionnaire (CHAQ) at each time-point. The drug safety profile was evaluated. Patients were categorized as responders, partial responders and non-responders. RESULTS: Four of nine patients had a benefit at a dose of 0.005 mg/kg/day of oral betamethasone. Using the higher dosage, only one additional patient had a positive response. Conversely, a daily dose of 0.001 mg/kg was ineffective. A correlation between the serum adrenocorticotropic hormone levels and the clinical response was observed. Five of 30 CHAQ items improved in four patients. CONCLUSIONS: These data suggest that a short-term betamethasone oral treatment, at a daily dosage of 0.005 mg/kg, is effective in some patients. Pre-existing risk factors for side effects should be taken into account before therapy.

Anti-infective prophylaxis for primary immunodeficiencies: what is done in Italian Primary Immunodeficiency Network centers (IPINet) and review of the literature.

Primary immunodeficiencies (PIDs) are rare diseases characterized by an increased susceptibility to infections. Early diagnosis and appropriate treatment are critical for reducing morbidity and mortality. Based on available data, the efficacy of antibiotic administration for the prophylaxis of infections remains uncertain, and recommendations supporting this practice are poor. The use of antimicrobial prophylaxis is mainly based on single institution-specific experience without controlled measurements of patient safety and quality health outcomes. To address this issue an Italian Network on Primary Immunodeficiencies (IPINet) has been set up in 1999 within the Italian Association of Pediatric Hematology and Oncology (AIEOP) to increase the awareness of these disorders among physicians. Further, diagnostic and treatment guideline recommendations have been established to standardize the best clinical assistance to all patients, including antibiotic prophylaxis, and for a national epidemiologic monitoring of PIDs. The aim of this review is not only to give a scientific update on the use of antimicrobial prophylaxis in selected congenital immunological disorders but also to draw a picture of this practice in the context of the Italian Primary Immunodeficiency Network (IPINet). Controlled multicenter studies are necessary to establish if, when and how you should start an efficacious antimicrobial prophylaxis.

Evaluation of CARMA1/CARD11 and Bob1 as candidate genes in common variable immunodeficiency.

BACKGROUND AND OBJECTIVE: The candidate gene approach has led to the detection of associations between common variable immunodeficiency (CVID) and mutations in the genes TACI, ICOS, BAFF-R, CD19, CD20, and CD81. Such mutations are present in less than 15% of cases, highlighting the complexity of the disease. Animal models for 2 genes involved in B-cell development, namely CARMA1/CARD11 and Bob1, develop an immunological phenotype similar to that seen in CVID, with low immunoglobulin serum levels, defective responses to antigen, and defective B-cell activation. The aim of this study was to evaluate CARMA1/CARD11 and Bob1 as candidate genes for the pathogenesis of CVID in a cohort of 66 patients with the disease. PATIENTS AND METHODS: We performed direct gene sequencing of CARMA1/CARD11 and Bob1 in 66 patients with CVID. RESULTS: Seven already reported genetic variants and 4 novel ones were found in the CARMA1/CARD11 gene, while 1 already reported variant and 1 novel variant were found in the Bob1 gene. CONCLUSIONS: Although novel genetic variants were identified in both the CARMA1/CARD11 and the Bob1 gene, no disease-causing mutations were identified in our group of patients. However, 4 of the variants in CARMA1 and 1 of those in Bob1 were associated with the disease. Considering the heterogeneity and complexity of CVID, further studies are needed to better define the genetic mechanisms involved in the pathogenesis of the disease.

Generation of induced Pluripotent Stem Cells (UNIBSi008-A, UNIBSi008-B, UNIBSi008-C) from an Ataxia-Telangiectasia (AT) patient carrying a novel homozygous deletion in ATM gene.

Using a Sendai Virus based vector delivering Yamanaka Factors, we generated induced Pluripotent Stem Cells (iPSCs) from peripheral blood mononuclear cells of a patient affected by Ataxia Telangiectasia (AT), caused by a novel homozygous deletion in ATM, spanning exons 5-7. Three clones were fully characterized for pluripotency and capability to differentiate. These clones preserved the causative mutation of parental cells and genomic stability over time (>100 passages). Furthermore, in AT derived iPSCs we confirmed the impaired DNA damage response after ionizing radiation. All these data underline potential usefulness of our clones as in vitro AT disease model.

A prospective study on children with initial diagnosis of transient hypogammaglobulinemia of infancy: results from the Italian Primary Immunodeficiency Network.

Transient hypogammaglobulinemia of infancy (THI) is a heterogeneous disorder characterized by reduced serum IgG levels in early infancy. A putative diagnosis is initially made after exclusion of other causes of hypogammaglobulinemia while a definitive diagnosis of THI can only be made a posteriori in patients with normalization of IgG levels. The aim of this study is to characterize clinical and immunological features of children with an initial diagnosis of THI in correlation to natural outcome, and to assess predictive laboratory parameters of clinical evolution for this disorder. We prospectively analysed clinical and immunological characteristics of 77 THI children at initial diagnosis and of 57 patients at follow-up. Memory B cell subsets and in vitro immunoglobulin production were evaluated. Seventy patients (91 percent) showed clinical symptoms. Patients suffered from infections (91 percent), allergies (47 percent) and autoimmune disease (4 percent). During follow-up 41/57 children (72 percent) normalized IgG values, mostly within 24 months of age (p less than 0.001), allowing the diagnosis of THI. The 16 children who did not normalize their IgG levels showed a higher frequency of severe infections and autoimmune disease (p less than 0.01). Moreover, they expressed a reduced frequency of IgM and switched memory B cells (p less than 0.01) and an inability to produce IgG in vitro (p less than 0.02). We conclude that most patients with an initial diagnosis of THI spontaneously recover within 24 months of age and have a benign clinical course, while a subgroup of children with undefined hypogammaglobulinemia share a clinical and immunological profile with other primary immunodeficiencies. Early recognition of children with hypogammaglobulinemia during infancy who are likely to suffer from permanent immunodeficiencies later in life would allow prompt and appropriate laboratory and clinical interventions.

A case report of a patient with microcephaly, facial dysmorphism, chromosomal radiosensitivity and telomere length alterations closely resembling "Nijmegen breakage syndrome" phenotype.

Genetic heterogeneity in Nijmegen breakage syndrome (NBS) is highlighted by patients showing clinical and cellular features of NBS but with no mutations in NBS1 and normal levels of nibrin. NBS is an autosomal recessive disorder, whose clinical cellular signs include growth and developmental defects, dysmorphic facies, immunodeficiency, cancer predisposition, chromosomal instability and radiosensitivity. NBS is caused by mutations in the NBS1 gene, whose product is part of the MRE11/RAD50/NBS1 complex involved in the DNA double-strand break (DSB) response pathway. Since the identification of the NBS1 gene, patients with NBS clinical signs, particularly severe congenital microcephaly, are screened for mutations in the NBS1 gene. Further analyses include X-ray-induced chromosome aberrations, telomere analysis, kinetics of DSBs repair, levels of a panel of proteins involved in the maintenance of genetic stability, radiation-induced phosphorylation of various substrates and cell cycle analysis. We describe a patient with a NBS clinical phenotype, chromosomal sensitivity to X-rays but without mutations in the whole NBS1 or in the Cernunnos gene. Enhanced response to irradiation was mediated neither by DSBs rejoining defects nor by the NBS/AT-dependent DNA-damage response pathway. Notably, we found that primary fibroblasts from this patient displayed telomere length alterations. Cross-talk between pathways controlling response to DSBs and those involved in maintaining telomeres has been shown in the present patient. Dissecting the cellular phenotype of radiosensitive NBS-like patients represents a useful tool for the research of new genes involved in the cellular response to DSBs.

Ontogeny of CD40L [corrected] expression by activated peripheral blood lymphocytes in humans.

The CD40 ligand (CD40L) is a molecule expressed by activated T cells which plays a critical role in the regulation of B-cell responses, including differentiation into Ig-producing cells. Using the specific monoclonal antibody TRAP1 we have evaluated the ontogeny of CD40L expression in 97 normal individuals between birth and 50 years of age. The expression of CD40L is a function of age; it is severely reduced at birth, progressively increases during the first months of life, and reaches a plateau in the second decade. This progressive attainment of the ability to express CD40L is due to a process of maturation of the CD4 + subset, being significantly correlated with the expression of the CD45RO antigen.

[The child with recurrent infections: a problem of pediatric practice]. / Il bambino con infezioni ricorrenti: un problema di pratica pediatrica.

A wide range of topics can be included under the heading of recurrent infections in children. This discussion focuses on 1) the definition of recurrent infection and physiopathogenetic mechanisms predisposing to; 2) controversies in the management of upper respiratory tract infections; 3) recurrent upper and lower respiratory infections in immunocompromised hosts, emphasizing advances in diagnosis and treatment of "mild" immunodeficiencies such as IgG subclass deficiency or antibody deficiency in normogammaglobulimia, trying to define an operative flow chart.

Different clinical and immunological presentation of ataxia-telangiectasia within the same family.

Ataxia-telangiectasia is a rare multisystem neurodegenerative genetic disorder due to mutation of ATM gene. The clinical expression and the immunological abnormalities are variable and apparently not associated with the type of ATM mutations. We report on two siblings affected by A-T with different clinical and immunological presentations; in particular in one the immunological phenotype was reminiscent of hyper IgM syndrome.

Molecular analysis of the pre-BCR complex in a large cohort of patients affected by autosomal-recessive agammaglobulinemia.

Autosomal-recessive agammaglobulinemia is a rare and heterogeneous disorder, characterized by early-onset infections, profound hypogammaglobulinemia of all immunoglobulin isotypes and absence of circulating B lymphocytes. To investigate the molecular basis of the disease, 23 patients with early-onset disease and no mutations in Bruton tyrosine kinase, the gene responsible for X-linked agammaglobulinemia, were selected and analyzed by direct sequencing of candidate genes. Two novel mutations in the mu heavy chain (muHC) gene (IGHM) were identified in three patients belonging to two unrelated families. A fourth patient carries a previously described G>A nucleotide substitution at the -1 position of an alternative splice site in IGHM; here, we demonstrate that this mutation is indeed responsible for aberrant splicing. Comparison of bone marrow cytofluorimetric profiles in two patients carrying different mutations in the IGHM gene suggests a genotype-phenotype correlation with the stage at which B-cell development is blocked. Several new single nucleotide polymorphisms (SNPs) both in the muHC and in the lambda5-like/VpreB-coding genes were identified. Two unrelated patients carry compound heterozygous variations in the VpreB1 gene that may be involved in disease ethiology.

Effect of HIV vertical transmission on the ontogeny of T cell antigens involved in the regulation of humoral immune response.

HIV infection causes progressive impairment of humoral immunity, including defective specific antibody production. To evaluate whether vertical HIV infection interferes with the expression on CD4+ lymphocytes of developmentally regulated molecules, that play a crucial role in the generation of immunological memory (CD45 isoforms) and in attainment of antibody responses (CD40L), 22 HIV-infected children and 36 seroreverted children born to HIV+ mothers were studied. The percentage of CD40L+ PBMC after activation in vitro with phorbol myristate acetate (PMA) plus ionomycin was lower in HIV-infected children than in controls (P < 0.004). This correlated with the depletion of CD4+ lymphocytes (r = 0.75; P < 0.001). CD40L expression rose progressively with age (r = 0.36; P = 0.03) in seroreverted children, but not in HIV-infected children, suggesting that while in normal children in vivo antigen stimulation results in progressive attainment of CD40L expression (and thus to effective T-B cell cooperation), this process is largely defective in HIV-infected children, contributing to the genesis of humoral immune deficiency. The proportion of CD4+ cells bearing the CD45RO isoform was increased among HIV-infected infants during the first years of life. However, the percentage of CD4+ CD45RO+ peripheral blood mononuclear cells (PBMC) progressively increased with age in controls (r = 0.69; P = 0.03), but not in HIV-infected children, showing that while vertical transmission of HIV does not prevent CD45RO expression early in life, it is associated with a disturbance of the physiological process of antigen priming, contributing to poor immunological memory to T cell-dependent antigens.

Mutations of CD40 gene cause an autosomal recessive form of immunodeficiency with hyper IgM.

CD40 is a member of the tumor necrosis factor receptor superfamily, expressed on a wide range of cell types including B cells, macrophages, and dendritic cells. CD40 is the receptor for CD40 ligand (CD40L), a molecule predominantly expressed by activated CD4(+) T cells. CD40/CD40L interaction induces the formation of memory B lymphocytes and promotes Ig isotype switching, as demonstrated in mice knocked-out for either CD40L or CD40 gene, and in patients with X-linked hyper IgM syndrome, a disease caused by CD40L/TNFSF5 gene mutations. In the present study, we have identified three patients with an autosomal recessive form of hyper IgM who fail to express CD40 on the cell surface. Sequence analysis of CD40 genomic DNA showed that one patient carried a homozygous silent mutation at the fifth base pair position of exon 5, involving an exonic splicing enhancer and leading to exon skipping and premature termination; the other two patients showed a homozygous point mutation in exon 3, resulting in a cysteine to arginine substitution. These findings show that mutations of the CD40 gene cause an autosomal recessive form of hyper IgM, which is immunologically and clinically undistinguishable from the X-linked form.