Effect of Class Switch Recombination Defect on the Phenotype of Ataxia-Telangiectasia Patients.

Objectives: Ataxia-telangiectasia (A-T) is an autosomal recessive neurodegenerative disorder with multisystem involvement caused by homozygous or compound heterozygous mutations in the ataxia telangiectasia mutated (ATM) gene which encodes a serine/threonine protein kinase. The aims of this study were to investigate class switch recombination (CSR) and to review the clinical and immunologic phenotypes of 3 groups of A-T patients, including A-T patients with CSR defects (CSR-D), A-T patients with selective immunoglobulin A deficiency (IgA-D) and A-T patients with normal Ig level. Methods: In this study, 41 patients with confirmed diagnosis of A-T (16 A-T patients with HIgM, 15 A-T patients with IgA-D, and 10 A-T patients with normal Ig levels) from Iranian immunodeficiency registry center were enrolled. B-cell proliferation, in vitro CSR toward IgE and IgA were compared between three groups as well as G2 radiosensitivity assay. Results: Earliest presentation of telangiectasia was a significant hallmark in A-T patients with CSR-D (p = .036). In this investigation, we found that the frequency of respiratory infection (p = .002), pneumonia (p = .02), otitis media (p = .008), chronic fever (p < .001), autoimmunity (p = .02) and hepatosplenomegaly (p = .03) in A-T patients with HIgM phenotype were significantly higher than the other groups. As expected IgE production stimulation and IgA CSR were perturbed in HIgM patients that were aligned with the higher readiosenstivity scores in this group. Conclusion: A-T patients with HIgM compared to other A-T patients presenting more infections and noninfectious complications, therefore, early detection and careful management of these patients is necessary.

Respiratory Complications in Patients with Hyper IgM Syndrome.

PURPOSE: Hyper Immunoglobulin M (HIgM) syndrome is a heterogeneous group of primary immunodeficiency disorders, characterized by recurrent infections and associated with decreased serum IgG and IgA, but normal or increased IgM. The aim of the present study was to evaluate respiratory manifestations in patients with HIgM syndrome. METHODS: A total number of 62 patients, including 46 males and 16 females were included in the present study. To investigate the respiratory complications among HIgM patients, we evaluated the clinical hospital records, immunologic and molecular diagnostic assays, pulmonary function tests (PFT), and high-resolution computed tomography (HRCT) scans. RESULTS: Pneumonia was the most common respiratory manifestation (n = 35, 56.4%), followed by otitis media (45.1%), sinusitis (33.8%), and bronchiectasis (14.5%). 52.1% of the patients had abnormal PFT results, with a predominant restrictive pattern of changes. HRCT scans demonstrated abnormal findings in 85.7% of patients with found mutations. Ten cases had hilar lymphadenopathy and para-hilar infiltrates in their HRCT findings. Genetic diagnosis was confirmed in 29 HIgM patients (72.4% CD40 ligand (CD40L) and 24.1% activation-induced cytidine deaminase (AICDA/AID) deficiencies). Majority of patients with CD40L (71.4%) and AID (57.1%) deficiencies had missense mutations. Pneumonia and abnormal high-resolution computed tomography (HRCT) findings were more frequent among patients with CD40L mutation. Respiratory failure constituted the major cause of mortality (37.5%) with majority of cases occurring in CD40L-deficient patients (50%). CONCLUSIONS: Respiratory complications are common in patients with HIgM syndrome. A proper awareness of respiratory manifestations in patients with HIgM may result in improved management, reduced morbidity and mortality, and an improvement in the quality of life of the patients.

Cohort of Iranian Patients with Congenital Agammaglobulinemia: Mutation Analysis and Novel Gene Defects.

OBJECTIVES: Impairment in early B-cell development can cause a predominantly antibody deficiency with severe depletion of peripheral B-cells. Mutations in the gene encoding for Bruton's-tyrosine-kinase (BTK) and the components of the pre-B-cell receptor complex or downstream signaling molecules have been related to this defect in patients with agammaglobulinemia. METHODS: Iranian patients with congenital agammaglobulinemia were included and the correlation between disease-causing mutations and parameters such as clinical and immunologic phenotypes were evaluated in available patients. RESULTS: Out of 87 patients, a molecular investigation was performed on 51 patients leading to identification of 39 cases with BTK (1 novel mutation), 5 cases of µ-heavy chain (3 novel mutations) and 1 case of Igα-deficiencies. CONCLUSION: Although there is no comprehensive correlation between type of responsible BTK mutation and severity of clinical phenotype, our data suggest that BTK-deficient and autosomal recessive agammaglobulinemia patients differ significantly regarding clinical/immunologic characteristics.