Gains of glycosylation comprise an unexpectedly large group of pathogenic mutations.

Mutations involving gains of glycosylation have been considered rare, and the pathogenic role of the new carbohydrate chains has never been formally established. We identified three children with mendelian susceptibility to mycobacterial disease who were homozygous with respect to a missense mutation in IFNGR2 creating a new N-glycosylation site in the IFNgammaR2 chain. The resulting additional carbohydrate moiety was both necessary and sufficient to abolish the cellular response to IFNgamma. We then searched the Human Gene Mutation Database for potential gain-of-N-glycosylation missense mutations; of 10,047 mutations in 577 genes encoding proteins trafficked through the secretory pathway, we identified 142 candidate mutations ( approximately 1.4%) in 77 genes ( approximately 13.3%). Six mutant proteins bore new N-linked carbohydrate moieties. Thus, an unexpectedly high proportion of mutations that cause human genetic disease might lead to the creation of new N-glycosylation sites. Their pathogenic effects may be a direct consequence of the addition of N-linked carbohydrate.

Impaired response to interferon-alpha/beta and lethal viral disease in human STAT1 deficiency.

The receptors for interferon-alpha/beta (IFN-alpha/beta) and IFN-gamma activate components of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, leading to the formation of at least two transcription factor complexes. STAT1 interacts with STAT2 and p48/IRF-9 to form the transcription factor IFN-stimulated gene factor 3 (ISGF3). STAT1 dimers form gamma-activated factor (GAF). ISGF3 is induced mainly by IFN-alpha/beta, and GAF by IFN-gamma, although both factors can be activated by both types of IFN. Individuals with mutations in either chain of the IFN-gamma receptor (IFN-gammaR) are susceptible to infection with mycobacteria. A heterozygous STAT1 mutation that impairs GAF but not ISGF3 activation has been found in other individuals with mycobacterial disease. No individuals with deleterious mutations in the IFN-alpha/beta signaling pathway have been described. We report here two unrelated infants homozygous with respect to mutated STAT1 alleles. Neither IFN-alpha/beta nor IFN-gamma activated STAT1-containing transcription factors. Like individuals with IFN-gammaR deficiency, both infants suffered from mycobacterial disease, but unlike individuals with IFN-gammaR deficiency, both died of viral disease. Viral multiplication was not inhibited by recombinant IFN-alpha/beta in cell lines from the two individuals. Inherited impairment of the STAT1-dependent response to human IFN-alpha/beta thus results in susceptibility to viral disease.

Monochrome LightCycler PCR assay for detection and quantification of five common species of Candida and Aspergillus.

Invasive fungal pathogens, especially in immunocompromised hosts, can result in life-threatening infections. Current laboratory/radiological methods for fungal identification are time-consuming and lack sensitivity and specificity. A monochrome, multiplex, real-time PCR assay for the identification and quantification of Candida albicans, Candida krusei, Candida tropicalis, Aspergillus flavus and Aspergillus fumigatus is described here. Detection of each of these fungi was specific and demonstrated 100 % concordance with biochemical/culture identification in all 60 isolates tested. Samples from 16 febrile neutropenic patients with haematological malignancies were also analysed and the utility of the assay in clinical samples was reconfirmed without false-negative results. The sensitivity of this assay was 0.1 pg fungal genomic DNA, corresponding to three cells, for C. albicans, C. krusei, C. tropicalis and A. flavus, and 0.01 pg fungal genomic DNA, i.e. less than one cell, for A. fumigatus. The analysis allows a low-cost, simple, rapid and sensitive alternative for clinical identification and quantification of these five common fungal species.

Successful treatment of a child with posttraumatic necrotizing fasciitis caused by Apophysomyces elegans: case report and review of literature.

Apophysomyces elegans is an uncommon human pathogen that causes deeply invasive infections in immunocompromised patients and cutaneous infection in immunocompetent patients. We report the development of severe deep soft tissue zygomycosis caused by A. elegans in an otherwise healthy child after trauma. She was successfully treated with surgical debridements and antifungal therapy with liposomal amphotericin B. A review of the literature indicates that zygomycosis caused by A. elegans is associated with traumatic inoculation.

Pediatric gastrointestinal basidiobolomycosis.

Basidiobolomycosisis an unusual fungal infection that manifests in the skin and rarely involves other systems including the gastrointestinal tract. We retrospectively reviewed records of six pediatric patients (< or =14 years of age) diagnosed with gastrointestinal basidiobolomycosis from March 2000 to March 2002. Four patients came from the same region, suggesting environmental exposure. Basidiobolomycosis should be considered in the differential diagnosis in pediatric patients presenting with abdominal mass and eosinophilia.

Ocular manifestations in chronic granulomatous disease in Saudi Arabia.

INTRODUCTION: Chronic granulomatous disease (CGD) is a primary immunodeficiency disease caused by a genetic defect in the NADPH oxidase complex of phagocytic cells. Recent reports indicate that chorioretinal lesions are more common than previously suspected. In this study, ocular findings of CGD patients are described with particular emphasis on chorioretinal lesions as a potentially serious ocular complication of CGD. METHODS: Medical records of CGD patients attending an immunodeficiency clinic at a tertiary care center from January 2004 to December 2006 were reviewed. Patients underwent full ophthalmologic examination. Patients with chorioretinal lesions were investigated for various causes of chorioretinitis. Molecular studies for common CGD-causing genes were performed in patients with chorioretinal lesions. RESULTS: This cohort included 32 CGD patients: 14 (44%) had abnormal eye findings, 11 (34%) had anterior segment disease, and 4 (12.5%) had chorioretinal lesions. Posterior segment findings consisted of uniformly similar hypopigmented atrophic punched-out chorioretinal scars around the arcades and mid-equator sparing of the macula. One patient had exudative hemorrhagic total retinal detachment in the right eye. Two siblings with chorioretinal lesions had mutation in CYBB, an X-linked gene. Another patient carried a missense mutation in NCF2, causing autosomal-recessive disease. CONCLUSIONS: While ocular manifestation is common in CGD, chorioretinal lesions seem less frequent. However, they present potential risk of visual loss; it is recommended that patients undergo regular ophthalmologic examinations. This report provides further evidence that chorioretinal lesions occur not only in X-linked, but they can also occur in the autosomal-recessive form of CGD.

Group B streptococcal endocarditis.

Group B Streptococcus can cause early onset neonatal disease. Beyond neonatal life, group B Streptococci are unusual pathogens. It can cause septicemia, epiglottis, fascitis, and endocarditis. A male Saudi child with group B endocarditis who has congenital heart disease is discussed.

Inherited interleukin-12 deficiency: IL12B genotype and clinical phenotype of 13 patients from six kindreds.

Interleukin-12 (IL12) is a cytokine that is secreted by activated phagocytes and dendritic cells and that induces interferon-gamma production by natural-killer and T lymphocytes. It consists of two subunits, p35 and p40, which are encoded by IL12A and IL12B, respectively. The first reported patient with a genetic cytokine disorder was a Pakistani child, who was homozygous for a large loss-of-function deletion (g.482+82_856-854del) in IL12B. This IL12-deficient child suffered from infections caused by bacille Calmette-Guérin (BCG) and Salmonella enteritidis. We herein report 12 additional patients from five other kindreds. In one kindred from India, the same large deletion that was described elsewhere (g.482+82_856-854del) was identified. In four kindreds from Saudi Arabia, a recessive loss-of-function frameshift insertion (g.315_316insA) was found. A conserved haplotype encompassing the IL12B gene suggested that a founder effect accounted for the recurrence of each mutation. The two founder mutational events-g.482+82_856-854del and g.315_316insA-were estimated to have occurred approximately 700 and approximately 1,100 years ago, respectively. Among a total of 13 patients with IL12 deficiency, 1 child had salmonellosis only and 12 suffered from clinical disease due to BCG or environmental nontuberculous mycobacteria. One patient also had clinical disease caused by virulent Mycobacterium tuberculosis, five patients had clinical disease caused by Salmonella serotypes, and one patient had clinical disease caused by Nocardia asteroides. The clinical outcome varies from case to case, since five patients (aged 2-11 years) died of overwhelming infection, whereas eight patients (aged 3-12 years) are still in good health and are not currently taking antibiotics. In conclusion, IL12 deficiency is not limited to a single kindred, shows significant variability of outcome, and should be considered in the genetic diagnosis of patients with mycobacteriosis and/or salmonellosis. To date, two founder IL12B mutations have been identified, accounting for the recurrence of a large deletion and a small insertion within populations from the Indian subcontinent and from the Arabian Peninsula, respectively.

Pyogenic bacterial infections in humans with IRAK-4 deficiency.

Members of the Toll-like receptor (TLR) and interleukin-1 receptor (IL-1R) superfamily share an intracytoplasmic Toll-IL-1 receptor (TIR) domain, which mediates recruitment of the interleukin-1 receptor-associated kinase (IRAK) complex via TIR-containing adapter molecules. We describe three unrelated children with inherited IRAK-4 deficiency. Their blood and fibroblast cells did not activate nuclear factor kappaB and mitogen-activated protein kinase (MAPK) and failed to induce downstream cytokines in response to any of the known ligands of TIR-bearing receptors. The otherwise healthy children developed infections caused by pyogenic bacteria. These findings suggest that, in humans, the TIR-IRAK signaling pathway is crucial for protective immunity against specific bacteria but is redundant against most other microorganisms.