Clinical use of basophil activation test in drug, food and hymenoptera venom allergies.

The basophil activation is emerging as a reliable and robust in vitro biomarker of in vivo allergy reactions. Basophil Activation Test (BAT), intended as in vitro stimulation of patient blood basophil with allergens, followed by flow cytometric detection and quantification of such activation, is nowadays a well-established assay in a growing number of routine diagnostic labs. The advancements in the standardization of BAT testing and first convincing clinical evidence are behind this spreading of the assay in clinical lab. BAT is essentially an assay with superior specificity compared to any other allergy testing and, if appropriately used, it can have a valuable clinical utility in different field of allergy diagnosis. In drug allergy, very few testing opportunities are available for the numbers of drugs actually in the market. Antibiotics and analgesics are just two of the categories of drugs were BAT testing can have an added value for the limited specificity of IgE testing or limited availability of other lab testing. In food allergy, BAT is emerging as the more accurate assay to predict an in vivo reaction to food, helping in the discrimination of patients that are only sensitized versus the patient really allergic to an allergen. Furthermore, BAT testing determining the basophil sensitivity can be useful for monitoring the natural resolution of allergies and clinical responses to immunomodulatory treatment for food allergies. For this characteristic, BAT has the potential to reduce the need of OFC. In the hymenoptera venom allergy, BAT is an effective tool in identifying primary sensitizing antigen and in the follow up of patient in venom immunotherapy. With this review, we want to present current state of BAT testing focusing on the clinical laboratory parameters and issue of this assay. A highlight on the standardization needs of BAT is provided, together with considerations on further developments and clinical evidences still to be achieved.

Pediatric GIST presenting as anemia.

Gastrointestinal stromal tumors (GIST) are tumors of the gastrointestinal (GI) tract originating from the myenteric ganglion cells (interstitial cells of Cajal), that are very rare in children and adolescents. The most common clinical manifestation is acute or chronic, overt or occult GI bleeding although these tumors are asymptomatic in 10-30% of patients. We report a case of gastric GIST in a 11-year-old girl presenting with an iron deficiency refractory anemia without gastrointestinal symptoms and stool evidence of GI bleeding that caused a slight diagnostic delay.

Efficacy and safety of ribosome-component immune modulator for preventing recurrent respiratory infections in socialized children.

Attending day care is associated with recurrent respiratory infections (RRIs) and asthma. Ribosomal immunotherapy may confer protection against RRIs in children. This study was designed to assess the efficacy of a ribosome-component immune modulator (RCIM) as preventive treatment of respiratory infections in socialized children aged ≤5 years, with or without a history of frequent RRI. In a multicenter, Italian, randomized, double-blind, placebo-controlled, parallel-group study, 164 socialized day care center children (mean age, 3.8 ± 1.1 years) were treated with RCIM or placebo for 6 months and followed-up for additional 6 months. Outcomes are presented for the intent-to-treat population. In socialized children with five or less RRIs (n = 95; 49 RCIM and 46 placebo, group A) the duration of the infectious episodes was significantly shorter with RCIM than with placebo (6 months, 3.7 ± 2.1 versus 4.5 ± 1.9 days, p = 0.040; 12 months, 3.6 ± 2.0 versus 4.7 ± 2.5 days, p = 0.015). The proportion of patients reporting no respiratory infectious episodes with RCIM at 6 and 12 months was also significantly larger in group A (20.4% versus 4.4% placebo; p = 0.028). No such differences were found in children with more than five RRIs in the preceding year (n = 63; 32 RCIM and 31 placebo, group B). In all children, general well-being improved significantly more under RCIM than under placebo (11.6 ± 1.8% versus 10.2 ± 1.8%; p = 0.002). No statistically significant between-treatment differences were observed for other end points. Both treatments were similarly well tolerated. Six-month treatment with RCIM effectively prevented the 12-month risk of RRIs in children <5 years old and with five or less RRIs in the preceding year.

Prevalence of the congenital long-QT syndrome.

BACKGROUND: The prevalence of genetic arrhythmogenic diseases is unknown. For the long-QT syndrome (LQTS), figures ranging from 1:20 000 to 1:5000 were published, but none was based on actual data. Our objective was to define the prevalence of LQTS. METHODS AND RESULTS: In 18 maternity hospitals, an ECG was performed in 44 596 infants 15 to 25 days old (43 080 whites). In infants with a corrected QT interval (QTc) >450 ms, the ECG was repeated within 1 to 2 weeks. Genetic analysis, by screening 7 LQTS genes, was performed in 28 of 31 (90%) and in 14 of 28 infants (50%) with, respectively, a QTc >470 ms or between 461 and 470 ms. A QTc of 451 to 460, 461 to 470, and >470 ms was observed in 177 (0.41%), 28 (0.06%), and 31 infants (0.07%). Among genotyped infants, disease-causing mutations were found in 12 of 28 (43%) with a QTc >470 ms and in 4 of 14 (29%) with a QTc of 461 to 470 ms. One genotype-negative infant (QTc 482 ms) was diagnosed as affected by LQTS on clinical grounds. Among family members of genotype-positive infants, 51% were found to carry disease-causing mutations. In total, 17 of 43 080 white infants were affected by LQTS, demonstrating a prevalence of at least 1:2534 apparently healthy live births (95% confidence interval, 1:1583 to 1:4350). CONCLUSIONS: This study provides the first data-based estimate of the prevalence of LQTS among whites. On the basis of the nongenotyped infants with QTc between 451 and 470 ms, we advance the hypothesis that this prevalence might be close to 1:2000. ECG-guided molecular screening can identify most infants affected by LQTS and unmask affected relatives, thus allowing effective preventive measures.

Probiotics and zinc in acute infectious gastroenteritis in children: are they effective?

OBJECTIVE: Several studies in recent decades have assessed the effects of different probiotics in acute gastroenteritis, showing that specific strains of Lactobacilli (mainly Lactobacillus casei GG) and Saccharomyces boulardii may exert some beneficial therapeutic actions, mainly when used in rotavirus gastroenteritis, at a high dose, and in the early phase. The mechanisms of action of probiotics are not completely elucidated but seem to involve a complex interaction among epithelial, molecular, metabolic, and immune responses. Data on the prevention of community-acquired, nosocomial, and travelers' diarrhea are currently conflicting. Because each micro-organism has different properties, an accurate selection of the strain, dose, and patient should be cautiously considered. METHODS AND RESULTS: Several reports from developing countries have demonstrated that supplements of zinc also provide significant reduction in stool output and duration, persistency, and severity of diarrhea. In view of the published data and of the different actions of zinc (such as improvement of the immune status, intestinal permeability, epithelial and enzymatic function, and electrolyte transport), the use of zinc as adjunctive therapy to oral rehydration solution has the potential to improve the management of diarrhea and decrease complications in children worldwide. In contrast to probiotics, which most trials in the developed world have used, there has been no trial with zinc performed in developed countries. CONCLUSION: Data on the effect of a combined administration of zinc and probiotics in acute gastroenteritis are urgently needed.

Interferon-gamma- and interleukin-4-producing T cells in Down's syndrome.

Down's syndrome (DS) associates with genetic-dependent dysregulation of the interferon (IFN) system. We used intracellular cytokine staining to analyse the percentages of IFN-gamma- and interleukin (IL)-4-producing T cells in the peripheral blood of patients with DS, individuals with mental retardation (MR), and healthy controls (HCs). The percentages of IFN-gamma-producing CD4(+) and CD8(+) T cells (IFGCs), namely Th1 (mean, 21.4+/-S.D. 1.3) and Tc1 (12.6+/-1.1), and the Th1/Th2 ratio (6.1+/-0.2) in DS were significantly higher than in MR (15.9+/-1.3, 7.9+/-0.6, 4.8+/-0.3) and in HCs (15.6+/-1.9, 7.2+/-1.1, 4.6+/-0.6). Most of the DS patients with high IFGC percentages were seropositive for anti-transglutaminase IgA. We found no correlation between sex, age, APOE genotypes, coexisting autoimmune diseases, susceptibility to infections, or degree of cognitive impairment and high IFGC percentages. This abnormality might thus contribute to immune dysfunction in DS without manifest clinical correlates.

Physical activity and diabetes.

Although physical activity is frequently recommended in the management of type Idiabetes it has not yet been established whether practising regular exercise could actually improve the long-term outcome of metabolic control. In this follow-up study we assessed the impact of long-term physical activity in patients with type 1 diabetes mellitus. We studied longitudinally 69 patients with type 1 diabetes mellitus, 43 boys and 26 girls aged at onset of the disease 8.98 +/- 3.90 years with a mean duration of the disease of 97 +/- 63 months. The patients were classified according to the duration of the disease in 3 groups [A:24-60 months (69); B: 61-120 months (41); C > or =121 months (19)]. The average time spent weekly doing exercise was recorded for each patient in the three duration periods taken into account. On average our patients reported 3.0 +/- 2.9 hours of physical activity per week. On the basis of the hour/week of physical activity we divided the patients into 4 groups [G1: <2 hrs/week (46%); G2: 2-4 hrs/week (29%); G3 >4 hrs/week (22%) > or =7 hrs/week (3%)]. The duration group B showed a significant lower HbAlc and HbA1c adjusted for duration of the disease in G4 compared to G2 (p < 0.05) and G3 (p < 0.05). No differences were found for insulin requirement, weight excess, blood pressure and heart rate between active and sedentary patients. According to our results we concluded that exercise can improve the quality of metabolic control only if it is adjusted to the training level of the patient.

Bone mineral density in diabetic children and adolescents: a follow-up study.

OBJECTIVE: To establish whether T1DM can affect bone mineral density (BMD) in children and adolescents. RESEARCH DESIGN AND METHODS: We performed a cross-sectional and longitudinal study of 57 diabetic children and adolescents and 57 normal controls. Total body and lumbar BMD and bone mineral content (BMC) were assessed by DXA (Lunar DPX) and volumetric transformation was calculated using the Katzman formula for total body BMD (BMAD) and using the Kroger formula for Lumbar BMD (L2L4BMDvol). BMC, BMAD, BMDspine, and L2L4BMDvol were adjusted for confounding factors such as age, gender, BMI, height, weight, and pubertal stage. RESULTS: BMDspine in the control group increased by 0.006 (g/cm(2))/year; while in the 39 diabetic patients longitudinally studied, it dropped by 0.006 (g/cm(2))/year during a follow-up period of 51 +/- 27 months. The average time spent weekly doing physical activity resulted in T1DM group directly correlated to BCM (P < 0.001) and inversely correlated with BMDspine (P < 0.05) and L2L4BMDvol (P < 0.01). L2L4BMDvol resulted significantly correlated with previous BMD spine (R = 0.63; P < 0.0001) and BMC evaluation (R = 0.42; P < 0.01) but not with BMAD. A second lumbar DXA evaluation performed in 38 patients after 1.00 +/- 0.16 years confirmed a small but significant decrease of 1.6% per year in L2L4BMDvol. The percentage of variation of L2L4BMDvol between the two evaluations was not correlated with the level of metabolic control, insulin requirement, and duration of the disease. Patients with complications showed similar L2L4BMDvol to patients without complications. CONCLUSIONS: Diabetic children and adolescents show a slight negative pattern of spine mineralization, which does not depend on metabolic control and microvascular complications.

Inhaled corticosteroids in childhood asthma: long-term effects on growth and adrenocortical function.

Inhaled corticosteroids (ICS) are the most potent of all the available inhaled treatments, and are effective medications for long-term control of asthma. However, their use in children is limited by the risk of systemic adverse effects. Although results reported in the literature on the adverse effects of ICS are conflicting and often restricted to a small number of cases with a limited follow-up, most of them show an early decrease in growth velocity without significant influence on final adult height. Partial adrenal suppression has also been demonstrated in children treated with ICS for more than 2 months. Only children with mild persistent, moderate, or severe asthma not controlled by non-corticosteroid drugs should be treated with ICS for long periods. The dose of ICS must be individually adjusted to minimize the possible adverse effects on growth, and all children with asthma receiving long-term treatment with ICS must be regularly evaluated for growth impairment, which may necessitate dose reduction or drug replacement.

"Governare il diabete" ("to steer diabetes"): a new proposal for diabetic camps.

"Governare il diabete" (the Italian translation of "to steer diabetes") is a project which gives young diabetics the opportunity of sailing with non-diabetic companions in a protected and educational environment. The education technique, based on the parallelism between sailing and diabetes, encourage correct self-management of both diabetes related and unrelated problems. The impact of the experience on self-esteem, quality of life and metabolic control is currently under investigation.

Obstructive sleep apnea syndrome in childhood.

Obstructive sleep apnea syndrome (OSAS) was first reported in 1976 by Guilleminault. This condition has been defined as a disorder of breathing during sleep characterized by prolonged partial/complete upper airway obstruction that disrupts normal ventilation and normal sleep patterns. The prevalence of this condition varies among the different populations but it is between 1 and 2% in preschool children when adenoid and tonsils volume has a major peak. Loud snoring is very common in these children but not always present. The diagnosis may be suggested by the facial appearance and by personal history but it must be confirmed by a polysomnography recording. OSAS has many associated morbidities which involve the cardiovascular system, the neurocognitive performance, the growth and the metabolic homeostasis. Obesity is a common associated condition and it impairs the therapeutic success. It should be considered when planning the treatment program: it should be stressed the obesity epidemic has already reached the European countries and it is now contributing to the "adult type" of OSAS which was quite rare in childhood until few years ago. The adenotonsillectomy is the most common therapeutic intervention but it is curative only in 2/3 of patients. Orthodontic approaches, associated with orofacial muscle reinforcing physiotherapy are helpful in most of these patients. To conclude we must stress that this condition is quite common and should be promptly diagnosed to prevent the multisystem morbidities; a multidisciplinary approach should be always offered to the parents of these children.

A precocious cerebellar ataxia and frequent Fever episodes in a 16-month-old infant revealing ataxia-telangiectasia syndrome.

Ataxia-telangiectasia (AT) is the most frequent progressive cerebellar ataxia in infancy and childhood. Immunodeficiency which includes both cellular and humoral arms has variable severity. Since the clinical presentation is extremely variable, a high clinical suspicion will allow an early diagnosis. Serum alpha-fetoprotein is elevated in 80-85% of patients and therefore could be used as a screening tool. Here, we present a case of a 5-year-old female infant who was admitted to our department at the age of 16 months because of gait disorders and febrile episodes that had begun at 5 months after the cessation of breastfeeding. Serum alfa-fetoprotein level was elevated. Other investigations showed leukocytopenia with lymphopenia, reduced IgG2 and IgA levels, and low titers of specific postimmunization antibodies against tetanus toxoid and Haemophilus B polysaccharide. Peripheral lymphocytes subsets showed reduction of T cells with a marked predominance of T cells with a memory phenotype and a corresponding reduction of naïve T cells; NK cells were very increased (41%) with normal activity. The characterization of the ATM gene mutations revealed 2 specific mutations (c.5692C > T/c.7630-2A > C) compatible with AT diagnosis. It was concluded that AT syndrome should be considered in children with precocious signs of cerebellar ataxia and recurrent fever episodes.

Symptomatic fever management among 3 different groups of pediatricians in Northern Lombardy (Italy): results of an explorative cross-sectional survey.

BACKGROUND: In the care of feverish children, symptomatic management is pivotal. Thus, the Italian Pediatric Society has recently published guidelines on fever management in children. Our aim was to investigate whether pediatric hospitalists, community pediatricians and pediatric residents differ in their every-day clinical practice with respect to symptomatic management of feverish children. METHODS: 79 out of 118 physicians involved in pediatric care in an area of Northern Lombardy (Italy) filled in a modified version of the questionnaire derived from the Swiss national survey on symptomatic fever management. RESULTS: Pediatric hospitalists (N = 29), community pediatricians (N = 30) and pediatric residents (N = 20) did not differ with respect to temperature threshold for symptomatic fever treatment, role of general appearance in modulating the threshold for fever management, first choice antipyretic drug, frequency of ibuprofen prescription, prescription of physical antipyresis, influence of exaggerated fear of fever on its management and potential to reassure families about this fear.On the other side, some significant differences were found. Pediatric residents more frequently lower the treatment threshold in children with a past history of febrile seizures (P < 0.001) and prescribe an aggressive treatment for fever not responding to the first antipyretic drug (P < 0.01) than their more experienced colleagues. Community pediatricians represent the unique investigated group using homeopathic remedies, both in the acute setting (P < 0.001) as well as a prophylaxis (P < 0.0001). Finally, paediatric residents less often (P < 0.05) stated to encounter exaggerated fear of fever among parents than their more experienced colleagues. CONCLUSIONS: The present explorative inquiry globally shows limited discordance among pediatric residents, community pediatricians and pediatric hospitalists with respect to symptomatic fever management.

Growth hormone therapy and respiratory disorders: long-term follow-up in PWS children.

CONTEXT: Adenotonsillar tissue hypertrophy and obstructive sleep apnea have been reported during short-term GH treatment in children with Prader-Willi syndrome (PWS). OBJECTIVE: We conducted an observational study to evaluate the effects of long-term GH therapy on sleep-disordered breathing and adenotonsillar hypertrophy in children with PWS. DESIGN: This was a longitudinal observational study. PATIENTS AND METHODS: We evaluated 75 children with genetically confirmed PWS, of whom 50 fulfilled the criteria and were admitted to our study. The patients were evaluated before treatment (t0), after 6 weeks (t1), after 6 months (t2), after 12 months (t3), and yearly (t4-t6) thereafter, for up to 4 years of GH therapy. The central apnea index, obstructive apnea hypopnea index (OAHI), respiratory disturbance index, and minimal blood oxygen saturation were evaluated overnight using polysomnography. We evaluated the adenotonsillar size using a flexible fiberoptic endoscope. RESULTS: The percentage of patients with an OAHI of >1 increased from 3 to 22, 36, and 38 at t1, t4, and t6, respectively (χ(2) = 12.2; P < .05). We observed a decrease in the respiratory disturbance index from 1.4 (t0) to 0.8 (t3) (P < .05) and the central apnea index from 1.2 (t0) to 0.1 (t4) (P < .0001). We had to temporarily suspend treatment for 3 patients at t1, t4, and t5 because of severe obstructive sleep apnea. The percentage of patients with severe adenotonsillar hypertrophy was significantly higher at t4 and t5 than at t0. The OAHI directly correlated with the adenoid size (adjusted for age) (P < .01) but not with the tonsil size and IGF-1 levels. CONCLUSION: Long-term GH treatment in patients with PWS is safe; however, we recommend annual polysomnography and adenotonsillar evaluation.

Serotonin transporter role in identifying similarities between SIDS and idiopathic ALTE.

OBJECTIVE: Considering previous genetic studies on sudden infant death syndrome (SIDS) and the role of L/L serotonin transporter (5HTT) genotype and correlated genes monoamine oxidase A (MAOA) and dopamine transporter (DAT) in unexpected death, an investigation was carried out verifying their involvement in apparent life-threatening events (ALTE and idiopathic form [IALTE]), also assessing common molecular basis with SIDS. METHODS: Differential diagnoses in 76 ALTE infants, distinguishing ALTE from IALTE was elaborated by using clinical-diagnostic data. Genotypes/allelic frequencies of DAT, MAOA, and 5HTT were determined in ALTE and IALTE infants and compared with data obtained from 20 SIDS and 150 controls. RESULTS: No association was found between DAT polymorphisms and ALTE/IALTE groups either at the genotype or allelic level (P range .11-.94). MAOA genotypes and allele data comparison between ALTE and controls was not significant; IALTE data showed a tendency for genotypes (P = .09) and were statistically significant for alleles (P = .036); however, MAOA significance disappeared once the Bonferroni correction was applied. 5HTT polymorphisms in IALTE remarked the role of L/L genotype (P < .00001) and L (P < .00001), as previously demonstrated in SIDS. CONCLUSIONS: Considering correspondence between 5HTT and MAOA in IALTE and SIDS, we hypothesize that the 2 syndromes are different expressions of a common ethiopathogenesis. In particular, genetic data suggest SIDS events could derive from IALTE episodes occurred during sleep, and therefore out of parental control. Despite its functional role, results highlight the usefulness of 5HTT as a valuable tracer of SIDS risk in IALTE infants. Owing to the small sample size, the results are to be considered preliminary and should be reevaluated in an independent sample.

Low adherence to influenza vaccination campaigns: is the H1N1 virus pandemic to be blamed?

BACKGROUND: Over the last few months, debates about the handling of the influenza virus A (H1N1) pandemic took place, in particular regarding the change of the WHO pandemic definition, economic interests, the dramatic communication style of mass media. The activation of plans to reduce the virus diffusion resulted in an important investment of resources. Were those investments proportionate to the risk? Was the pandemic overrated? The workload of the Pediatric Emergency Room (P.E.R.) at a teaching hospital in Varese (Northern Italy) was investigated in order to evaluate the local diffusion and severity of the new H1N1 influenza epidemic. DISCUSSION: A 100% increase of the number of P.E.R. visits, particularly for influenza-like illness, was recorded during weeks 42-46 of 2009 (October, 17 to November, 2); the low rate of hospitalization and the mild presentation of the infection gave rise to the conclusion that the pandemic risk was overrated. Mass media communications concerning the new virus created a disproportionate fear in the population that significantly enhanced the burden of cares at the hospital. In the absence of generally implemented measures for etiological diagnosis, the actual incidence of the H1N1 infection could not be estimated. Virus identification, in fact, was limited to children showing severe symptoms after consultancy with an infectious disease specialist. The alarming nature of the communication campaign and the choice to limit etiologic diagnosis to severe cases created a climate of uncertainty which significantly contributed to the massive admissions to the P.E.R.. SUMMARY: The communication strategy adopted by the mass media was an important element during the pandemic: the absence of clarity contributed to the spread of a pandemic phobia that appeared to result more from the sensationalism of the campaign than from infection with the novel influenza A variant of human, avian, swine origin virus. One relevant effect of the media coverage was the extremely low adherence rate to the vaccination campaign for the 2009-2010 and 2010-2011, especially among the high-risk population and health care workers. One positive consequence was, however, the spread of preventive hygiene measures, such as hand washing.

Air pollution, aeroallergens, and emergency room visits for acute respiratory diseases and gastroenteric disorders among young children in six Italian cities.

BACKGROUND: Past studies reported evidence of associations between air pollution and respiratory symptoms and morbidity for children. Few studies examined associations between air pollution and emergency room (ER) visits for wheezing, and even fewer for gastroenteric illness. We conducted a multicity analysis of the relationship between air pollution and ER visits for wheezing and gastroenteric disorder in children 0-2 years of age. METHODS: We obtained ER visit records for wheezing and gastroenteric disorder from six Italian cities. A city-specific case-crossover analysis was applied to estimate effects of particulate matter (PM), nitrogen dioxide, sulfur dioxide, ozone, and carbon monoxide, adjusting for immediate and delayed effects of temperature. Lagged effects of air pollutants up to 6 prior days were examined. The city-specific results were combined using a random-effect meta-analysis. RESULTS: CO and SO(2) were most strongly associated with wheezing, with a 2.7% increase [95% confidence interval (CI), 0.5-4.9] for a 1.04-microg/m(3) increase in 7-day average CO and a 3.4% (95% CI, 1.5-5.3) increase for an 8.0-microg/m(3) increase in SO(2). Positive associations were also found for PM with aerodynamic diameter < or = 10 microg and NO(2). We found a significant association between the 3-day moving average CO and gastroenteric disorders [3.8% increase (95% CI, 1.0-6.8)]. When data were stratified by season, the associations were stronger in summer for wheezing and in winter for gastroenteric disorders. CONCLUSION: Air pollution is associated with triggering of wheezing and gastroenteric disorders in children 0-2 years of age; more work is needed to understand the mechanisms to help prevent wheezing in children.

A novel immunodeficiency characterized by the exclusive presence of transitional B cells unresponsive to CpG.

The objective of this study was to describe a novel form of primary immune disorder characterized by circulating B cells with the exclusive transitional phenotype which fail to respond to CpG stimulation. The 12-year-old male patient suffered from recurrent bacterial infections since infancy. The immunological studies were based on extensive B cell immunophenotyping, humoral in vivo response to different vaccine antigens, and in vitro proliferation and immunoglobulin production after CpG stimulation. Sequence analysis for potentially candidate genes such as IRF8, MyD88, TLR9, T-bet were performed. The patient's serum immunoglobulin levels and the specific antibody response to tetanus toxoid were normal, whereas that to polysaccharide antigens was severely impaired. Flow cytometric analysis showed that almost all patient's peripheral B cells had the transitional phenotype (CD24(bright) CD38(bright) CD27(neg)). Furthermore, the patient's B cells did not proliferate and failed to secrete immunoglobulins after in vitro CpG stimulation. Sequence analysis for TLR9, MyD88, IRF8 and T-bet showed no mutations. To our knowledge, this is the first case of a novel primary immunodeficiency mimicking the clinical phenotype of common variable immunodeficiency, with a peculiar immunological phenotype characterized by normal immunoglobulin serum levels, circulating B cells with the exclusive transitional phenotype unable to respond to CpG stimulation. This defines a novel form of primary immunodeficiency mimicking common variable immunodeficiency in the presence of normal immunoglobulin serum levels.