Utility of the QuantiFERON-TB Gold In-Tube assay for the diagnosis of tuberculosis in Moroccan children.

SETTING: The utility of interferon-gamma release assays (IGRAs), such as the QuantiFERON-TB Gold In-Tube (QFT-GIT) test, in diagnosing active tuberculosis (TB) in children is unclear and depends on the epidemiological setting. OBJECTIVE: To evaluate the performance of QFT-GIT for TB diagnosis in children living in Morocco, an intermediate TB incidence country with high bacille Calmette-Gurin vaccination coverage. DESIGN: We prospectively recruited 109 Moroccan children hospitalised for clinically suspected TB, all of whom were tested using QFT-GIT. RESULTS: For 81 of the 109 children, the final diagnosis was TB. The remaining 28 children did not have TB. QFT-GIT had a sensitivity of 66% (95%CI 5277) for the diagnosis of TB, and a specificity of 100% (95%CI 88100). The tuberculin skin test (TST) had lower sensitivity, at 46% (95%CI 3360), and its concordance with QFT-GIT was limited (69%). Combining QFT-GIT and TST results increased sensitivity to 83% (95%CI 6992). CONCLUSION: In epidemiological settings such as those found in Morocco, QFT-GIT is more sensitive than the TST for active TB diagnosis in children. Combining the TST and QFT-GIT would be useful for the diagnosis of active TB in children, in combination with clinical, radiological and laboratory data.

A genome-wide association study of pulmonary tuberculosis in Morocco.

Although epidemiological evidence suggests a human genetic basis of pulmonary tuberculosis (PTB) susceptibility, the identification of specific genes and alleles influencing PTB risk has proven to be difficult. Previous genome-wide association (GWA) studies have identified only three novel loci with modest effect sizes in sub-Saharan African and Russian populations. We performed a GWA study of 550,352 autosomal SNPs in a family-based discovery Moroccan sample (on the full population and on the subset with PTB diagnosis at <25 years), which identified 143 SNPs with p < 1 × 10(-4). The replication study in an independent case/control sample identified four SNPs displaying a p < 0.01 implicating the same risk allele. In the combined sample including 556 PTB subjects and 650 controls these four SNPs showed suggestive association (2 × 10(-6) < p < 4 × 10(-5)): rs358793 and rs17590261 were intergenic, while rs6786408 and rs916943 were located in introns of FOXP1 and AGMO, respectively. Both genes are involved in the function of macrophages, which are the site of latency and reactivation of Mycobacterium tuberculosis. The most significant finding (p = 2 × 10(-6)) was obtained for the AGMO SNP in an early (<25 years) age-at-onset subset, confirming the importance of considering age-at-onset to decipher the genetic basis of PTB. Although only suggestive, these findings highlight several avenues for future research in the human genetics of PTB.

Pott's disease in Moroccan children: clinical features and investigation of the interleukin-12/interferon-γ pathway.

SETTING: Tuberculosis spondylodiscitis (TS), or Pott's disease, an extra-pulmonary form of tuberculosis (TB), is rare and difficult to diagnose in children. Some cases of severe TB in children were recently explained by inborn errors of immunity affecting the interleukin-12/interferon-gamma (IL-12/IFN-γ) axis. OBJECTIVE: To analyse clinical data on Moroccan children with TS, and to perform immunological and genetic explorations of the IL-12/IFN-γ axis. DESIGN: We studied nine children with TS diagnosed between 2012 and 2014. We investigated the IL-12/IFN-γ circuit by both whole-blood assays and sequencing of the coding regions of 14 core genes of this pathway. RESULTS: A diagnosis of TS was based on a combination of clinical, biological, histological and radiological data. QuantiFERON(®)-TB Gold In-Tube results were positive in 75% of patients. Whole-blood assays showed normal IL-12 and IFN-γ production in all but one patient, who displayed impaired decreased response to IL-12. No candidate disease-causing mutations were detected in the exonic regions of the 14 genes. CONCLUSIONS: TS diagnosis in children remains challenging, and is based largely on imaging. Further investigations of TS in children are required to determine the role of genetic defects in pathways that may or may not be related to the IL-12/IFN-γ axis.

Pineal germinoma in a child with interferon-γ receptor 1 deficiency. case report and literature review.

Interferon-γ receptor 1 (IFN-γR1) deficiency is one of the primary immunodeficiencies conferring Mendelian Susceptibility to Mycobacterial Disease (MSMD). Some cases of neoplasms have been recently reported in patients with MSMD, underlying the already known link between immunodeficiency and carcinogenesis. We report the first case of intracranial tumour, i.e. pineal germinoma, in a 11-year-old patient with complete IFN-γR1 deficiency. The first clinical presentation of the genetic immunodeficiency dates back to when the child was aged 2 y and 10 mo, when he presented a multi-focal osteomyelitis caused by Mycobacterium scrofulaceum. The diagnosis of IFN-γR1 deficiency (523delT/523delT in IFNGR1 gene) was subsequently made. The child responded to antibiotic therapy and remained in stable clinical condition until the age of 11 years, when he started complaining of frontal, chronic headache. MRI revealed a solid pineal region mass lesion measuring 20 × 29 × 36 mm. Histological findings revealed a diagnosis of pineal germinoma. The patient received chemotherapy followed by local whole ventricular irradiation with boost on pineal site, experiencing complete remission, and to date he is tumor-free at four years follow-up. Four other cases of tumors have been reported in patients affected by MSMD in our knowledge: a case of Kaposi sarcoma, a case of B-cell lymphoma, a case of cutaneous squamous cell carcinoma and a case of oesophageal squamous cell carcinoma. In conclusion, in patients with MSMD, not only the surveillance of infectious diseases, but also that of tumors is important.

[Human genetics of tuberculosis]. / Génétique humaine de la tuberculose.

Tuberculosis (TB), caused by Mycobacterium tuberculosis, remains a major public health problem worldwide, resulting in 8.7 million new cases and 1.4 million deaths each year. One third of the world's population is exposed to M. tuberculosis and, after exposure, most, but not all, individuals become infected. Among infected subjects, only a minority (∼10%) will eventually develop clinical disease, which is typically either a primary, often extra-pulmonary, TB in children, or a reactivation, pulmonary TB in adults. Considerable genetic epidemiological evidence has accumulated to support a major role for human genetic factors in the development of TB. Numerous association studies with various candidate genes have been conducted in pulmonary TB, with very few consistent results. Recent genome-wide association studies revealed only a modest role for two inter-genic polymorphisms. However, a first major locus for pulmonary TB was mapped to chromosome 8q12-q13 in a Moroccan population after a genome-wide linkage screen. Using a similar strategy, two other major loci controlling TB infection were recently identified. While the precise identification of these major genes is ongoing, the other fascinating observation of these last years was the demonstration that TB can also reflect a Mendelian predisposition. Following the findings obtained in the syndrome of Mendelian susceptibility to mycobacterial diseases, several children with complete IL-12Rß1 deficiency, were found to have severe TB as their sole phenotype. Overall, these recent findings provide the proof of concept that the human genetics of TB involves a continuous spectrum from Mendelian to complex predisposition with intermediate major gene involvement. The understanding of the molecular genetic basis of TB will have fundamental immunological and medical implications, in particular for the development of new vaccines and treatments.

Bacille Calmette-Guérin lymphadenitis and recurrent oral candidiasis in an infant with a new mutation leading to interleukin-12 receptor beta-1 deficiency.

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare syndrome characterized by predisposition to infections caused by weakly virulent mycobacteria, such as those in bacille Calmette-Guérin (BCG) vaccine and environmental mycobacteria. Salmonellosis has been reported in almost half of affected patients. Patients are also vulnerable to Mycobacterium tuberculosis infection. Several other infectious diseases may occur, albeit rarely. Mucocutaneous candidiasis is more common. Interleukin-12 receptor beta1 (IL-12Rbeta1) deficiency is the most frequent genetic cause of MSMD. Here, we describe an infant with a single episode of BCG lymphadenitis who also suffered from recurrent oral candidiasis. Genetic analysis revealed a new homozygous mutation (64+1G>T) in the IL12RB1 gene that caused complete IL-12R1beta1 deficiency. IL-12Rbeta1 deficiency should be considered in patients with BCG infection, even in those who experience a single episode of BCG lymphadenitis or recurrent mucocutaneous candidiasis. Every attempt should be made to heighten awareness in countries where BCG vaccination is performed.