Immunoglobulin G (IgG) subclass deficiency in Thai children.

Background: Patients with Immunoglobulin G (IgG) subclass deficiency may suffer from recurrent infections, mainly sino-pulmonary infection. Objective: To determine the epidemiology of IgG subclass deficiency in Thai children at a tertiary care hospital and to compare the differences between children who were diagnosed with IgG subclass deficiency by using low level criteria [less than 2 standard deviation (SD) of normal levels for age] and by using low percentage criteria (proportion of each IgG subclasses/total IgG). Methods: The study was a descriptive study of 55 children up to 15 years old with recurrent infections diagnosed as having IgG subclass deficiency but no acquired or other primary immune deficiencies except for IgA and/or IgM deficiency. Result: Isolated IgG3 subclass deficiency was the most common IgG subclass deficiency (56.4%). IgG3 subclass deficiency, either isolated or combined with other IgG subclass deficiency, was found in 85.5% of the cases. The common age of onset was between birth and five years of age. The most common presenting symptom was recurrent sinusitis (83.6%). Majority of the cases (89.3%) were diagnosed by low percentage criteria while 12.7% were diagnosed by low level criteria. All cases with low levels of IgG subclass antibodies also had low percentages. There were no statistically significant differences in the clinical manifestations and management methods between the children who were diagnosed by low level and low percentage. Conclusion: IgG3 subclass deficiency was the most common IgG subclass deficiency in Thai children. The most common presenting symptom was recurrent sinusitis. Although the diagnosis could be made in the patients with recurrent upper respiratory infection by using low level criteria, but the diagnosis should be considered when the low percentage criteria are met.

A novel mutation of the IL12RB1 gene in a child with nocardiosis, recurrent salmonellosis and neurofibromatosis type I: First case report from Thailand.

Genetic defects of interleukin (IL)-12/23-and interferon (IFN)-γ-mediated immunity can cause in-creased susceptibility to intracellular microbes. Among these defects, a mutation of the gene encoding the IL-12 receptor β1 (IL-12Rβ1) is the most common worldwide. A 12-year old Thai boy with pre-existing neurofibromatosis type 1 (NF1) was evaluated for primary immunodeficiency after a history of tuberculous lymphadenitis, recurrent Salmonella infections and nocardiosis. Flow cytometry of phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMCs) revealed a defect in the IL-12Rβ1 surface expression. A genetic study showed a novel nonsense homozygous mutation of the IL12RB1 gene in exon 4 (402C>A), confirming the diagnosis of IL-12Rβ1 deficiency. This is the first case report of a primary IL-12Rβ1 deficiency in Thailand with the interesting finding of a coexisting NF1.

Association between ADAM33 polymorphisms and asthma in a Thai population.

ADAM33 (A Disintegrin And Metalloprotease 33) is an asthma susceptibility gene found across several human populations. However, no information on ADAM33 exists for Thai population. The objective of this study was to determine the association, if any, between ADAM33 polymorphisms and asthma in Thai subjects. Genotyping revealed 8 single nucleotide polymorphisms (SNPs) within the 3' region of the ADAM33 gene among 200 asthmatics and 100 control subjects. Asthmatic subjects were further sub-categorized into high and low severity groups. Multiple genetic model statistic tests for single-marker and haplotype association were carried out. Differences in allele frequencies at the SNPs rs528557/S2, rs598418 and rs44707/ST+4 in asthmatics were statistically significant compared to controls. The SNP rs528557/S2 could also be linked to the low severity group and the SNPs rs598418 and rs44707/ST+4 with the high severity group. Two-SNP haplotype analysis at the SNPs rs528557/S2 and rs598418 revealed a significant association with asthma. This study in a Thai population confirmed a positive association between ADAM33 polymorphisms and asthma susceptibility.

A novel mutation of the CYBB gene resulting in severe form of X-linked chronic granulomatous disease.

We evaluated a boy who had multiple Salmonella septicemia, Aspergillus pneumonia and brain abscesses. His nitroblue tetrazolium (NBT) test was reportedly abnormal. The dihydrorhodamine (DHR) flow cytometry assay was compatible with typical X-linked chronic granulomatous disease (X-CGD). CYBB analysis revealed a novel complex mutation atggacg --> ttca in exon 12 (base pairs 1532-1538). As a result, 3 amino acids Tyr 511, Gly 512 and Arg 513 were deleted and replaced by 2 amino acids, Phe and Gln. The DHR and mutation analysis of his mother showed normal DHR pattern and no mutations in exon 12 of CYBB gene. In conclusion, any children with multiple Salmonella and Aspergillus infection should be suspected of CGD. NBT test, DHR assay and gene analysis are helpful toolsto confirm the diagnosis e v en i n the case of de novo mutation.

Chronic diarrhea and abnormal serum immunoglobulin levels: a case report.

A 15-year-old Thai boy with multiple episodes of chronic diarrhea caused by giardiasis with hypogammaglobulin M and IgG4 subclass deficiency (but normal antibody response to rabies vaccine) is reported. Immune status follow-up is necessary for a definite diagnosis and proper management.

Recurrent Campylobacter lari bacteremia in X-linked agammaglobulinemia: a case report and review.

X-linked agammaglobulinemia (XLA) is a primary immune deficiency disease with a B-cell defect. We present the first XLA patient who had recurrent Campylobacter lari bacteremia. High dose intravenous immunoglobulin combined with azithromycin once per week, and a complete avoidance of bacterial reservoirs may be helpful for the prevention of C. lari bacteremia.

Chronic rhinosinusitis and recurrent nasal polyps in two children with IgG subclass deficiency and review of the literature.

Chronic rhinosinusitis (CRS) is a chronic inflammatory disorder of mucosa of the nose and the paranasal sinuses. Two major forms of CRS can be differentiated; CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). The pathophysiology and etiology of nasal polyps (NPs) are partly understood. IgG subclass deficiency was shown to be associated with an increased susceptibility to infections. However the association between NPs and IgG subclass deficiency has never been reported. OBJECTIVES: To report two cases of recalcitrant CRS and recurrent NPs with IgG subclass deficiency. CASE REPORT: Two children (6 and 8 year-old boys) were referred to the Pediatric Allergy/Immunology Clinic, Siriraj Hospital due to a prolonged history of CRS and recurrent NPs. Both of them were treated with aggressive medical (topical and systemic corticosteroids, antibiotics, leukotriene antagonist, nasal irrigation) as well as surgical therapy, without significant improvement. Immunologic investigation in both patients showed that IgG, IgA, and IgM level were normal. IgG subclasses level in patient No. 1 were IgG1 1,235 (280-1120) mg/dl (79%), IgG2 235 (30-630) mg/dl (23.5%), IgG3 27.3 (40-250) mg/dl (1.74%), and IgG4 92.4 (11-620) mg/dl (5.9%). IgG subclasses level in patient No. 2 were IgG1 1,139 (280-1120) mg/dl (82.5%), IgG2 170 (30-630) mg/dl (12.3%), IgG3 5.6 (40-250) mg/dl (0.4%), IgG4 65.7 (11-620) mg/dl (4.8%). The diagnosis of CRS and recurrent NPs with IgG3 subclass deficiency in the first patient and IgG2/IgG3 subclass deficiency in the second patient were made. Patient No. 1 was given monthly IVIG therapy for the total of 7 courses and medications were gradually tapered. Currently, the patient is doing well after the cessation of IVIG therapy for 3 months. Patient No. 2 denied the IVIG treatment and was lost to follow up. CONCLUSION: We reported two cases of recalcitrant CRS and recurrent NPs in children. Immunologic work up revealed IgG subclass deficiency. The treatment with monthly IVIG improved CRS and NPs in treated patient which brought up the possibility of association between NPs and IgG subclass deficiency. Further study on the direct role of IVIG in NPs will be needed in the future.

Detection of hepatitis C virus RNA by polymerase chain reaction: Design of amplification primers.

New sets of primers for amplification of hepatitis C virus (HCV) RNA were designed from the conserved regions of American and Japanese isolates of HCV. Primers set A amplified parts of the 5’-untranslated and core gene regions, whereas set B amplified parts of the core and envelope gene regions. PCR amplification were carried out from HCV RNA isolated from sera of 13 Thai patients with antibody to HCV, using these newly developed primers. HCV RNA was detectable in 8 patients (61.5%). Of those PCR positive samples, only 4 patients (50%) were positive with primer set A, whereas 7 patients (87.5%) were positive with primer set B. Interestingly, 4 patients were tested positive with only set B, 3 patients with both sets A and B, and just one patient with set A only. This result suggests that PCR assay as a diagnostic tool for HCV may need to be carried out with more than one primer set. The relatively low percentage of PCR positivity of the HCV from Thai patients using primer set A, which was previously identified as the most conserved region of the HCV genome, also indicates that the sequence of the Thai isolates of the virus may be different from those of the American and Japanese strains.