Human Genetic and Immunological Determinants of SARS-CoV-2 Infection and Multisystem Inflammatory Syndrome in Children.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces pneumonia and acute respiratory failure in Coronavirus Disease 2019 (COVID-19) patients with inborn errors of immunity to type I interferon (IFN-I). The impact of SARS-CoV-2 infection varies widely, ranging from mild respiratory symptoms to life-threatening illness and organ failure, with a higher incidence in men than in women. Approximately 3 to 5% of critical COVID-19 patients under 60 and a smaller percentage of elderly patients exhibit genetic defects in IFN-I production, including X-chromosome-linked TLR7 and autosomal TLR3 deficiencies. Around 15 to 20% of cases over 70 years old, and a smaller percentage of younger patients, present with preexisting autoantibodies neutralizing type I interferons. Additionally, innate errors affecting the control of the response to type I interferon have been associated with pediatric multisystem inflammatory syndrome (MIS-C). Several studies have described rare errors of immunity, such as XIAP deficiency, CYBB, SOCS1, OAS1/2, and RNASEL, as underlying factors in MIS-C susceptibility. However, further investigations in expanded patient cohorts are needed to validate these findings and pave the way for new genetic approaches to MIS-C. This review aims to present recent evidence from the scientific literature on genetic and immunological abnormalities predisposing individuals to critical SARS-CoV-2 infection through IFN-I. We will also discuss multisystem inflammatory syndrome in children (MIS-C). Understanding the immunological mechanisms and pathogenesis of severe COVID-19 may inform personalized patient care and population protection strategies against future serious viral infections.

Genetic Diagnosis of Inborn Errors of Immunity in an Emerging Country: a Retrospective Study of 216 Moroccan Patients.

PURPOSE: Genetic testing provides great support to validate the clinical diagnosis of inborn errors of immunity (IEI). However, the high cost and advanced technology make these tests inaccessible to a large proportion of patients in low-income countries. In the present study, we aim to evaluate the Moroccan experience in genetic testing and to report the main molecular features and difficulties encountered in genetic diagnosis. METHODS: We performed a multi-center retrospective analysis of all patients with a molecular diagnosis and registered in the national registry between 2010 and 2022. To estimate the impact of the newly identified mutations, we calculated the Combined Annotation Dependent Depletion (CADD) score and the mutation significance cutoff (MSC) for each variant. RESULTS: A total of 216 (29%) patients received a genetic diagnosis out of 742 patients with IEI included in the registry. All genetic tests were performed in the context of thesis projects (40%) or international collaborations (60%). A set of 55 genetic defects were identified, including 7 newly reported: SNORA31, TBX21, SPPL2A, TYK2, RLTPR, ZNF341, and STAT2 GOF. Genetic diagnoses were more frequent in the defects of innate and intrinsic immunity with a percentage of 78%, while antibody deficiencies had a lower frequency with a percentage of 17.5%. Only one genetic diagnosis has been made in the complement deficiency group. The most commonly used molecular techniques were Sanger sequencing (37%) followed by targeted gene sequencing (31%). CONCLUSION: The thesis projects and collaborations were beneficial as they allowed us to provide a definitive genetic diagnosis to 29% of the patients and to contribute to the identification of new genetic defects and mutations. These results offer insight into the progress made in genetic diagnoses of IEI in Morocco, which would provide a baseline for improving the clinical management of patients with IEI.

Mendelian Susceptibility to Mycobacterial Disease (MSMD): Clinical, Immunological, and Genetic Features of 22 Patients from 15 Moroccan Kindreds.

PURPOSE: The first molecular evidence of a monogenic predisposition to mycobacteria came from the study of Mendelian susceptibility to mycobacterial disease (MSMD). We aimed to study this Mendelian susceptibility to mycobacterial diseases in Moroccan kindreds through clinical, immunological, and genetic analysis. METHODS: Patients presented with clinical features of MSMD were recruited into this study. We used whole blood samples from patients and age-matched healthy controls. To measure IL-12 and IFN-γ production, samples were activated by BCG plus recombinant human IFN-γ or recombinant human IL-12. Immunological assessments and genetic analysis were also done for patients and their relatives. RESULTS: Our study involved 22 cases from 15 unrelated Moroccan kindreds. The average age at diagnosis is 4 years. Fourteen patients (64%) were born to consanguineous parents. All patients were vaccinated with the BCG vaccine, and twelve of them (55%) developed locoregional or disseminated BCG infections. The other symptomatic patients had severe tuberculosis and/or recurrent salmonellosis. Genetic mutations were identified on the following genes: IL12RB1 in 8 patients, STAT1 in 7 patients; SPPL2A, IFNGR1, and TYK2 in two patients each; and TBX21 in one patient, with different modes of inheritance. All identified mutations/variants altered production or response to IFN-γ or both. CONCLUSION: Severe forms of tuberculosis and complications of BCG vaccination may imply a genetic predisposition present in the Moroccan population. In the presence of these infections, systematic genetic studies became necessary. BCG vaccination is contraindicated in MSMD patients and should be delayed in newborn siblings until the exclusion of a genetic predisposition to mycobacteria.

Mendelian susceptibility to mycobacterial diseases: State of the puzzle.

The constant progress of genomics and the establishment of new functional tests have paved the way for identifying monogenic defects conferring a selective predisposition to infections by certain microbes as a new type of inborn errors of immunity (IEIs). Mendelian susceptibility to mycobacterial diseases (MSMD) is the most characterized of these IEIs, with 36 different disorders found in 20 distinct genes (IFNGR1, IFNGR2, IFNG, IL12RB1, IL12RB2, IL23R, IL12B, ISG15, USP18, ZNFX1, TBX21, STAT1, TYK2, IRF8, IRF1, CYBB, JAK1, RORC, NEMO, and SPPL2A) over the last 20 years. MSMD confers a selective susceptibility to infections with weakly virulent mycobacteria, including the M. bovis Bacille Calmette-Guerin (BCG) vaccines and various environmental mycobacteria in patients, primarily children, without classical immune defects. These patients may also present severe forms of tuberculosis, and about half of them might develop non-typhoidal salmonellosis. In some cases, patients also suffer from chronic mucocutaneous candidiasis (CMC), while in others, patients also present severe viral, parasitic, fungal, and/or bacterial diseases. Despite this clinical and genetic heterogeneity, almost all genetic etiologies of MSMD alter the interferon-gamma (IFN-γ)- mediated immunity by impairing or abolishing IFN-γ production or the response to this cytokine. It was proven that the human IFN-γ level is a quantitative trait that defines the outcome of mycobacterial infection. The study of these monogenic defects contributes to understanding the molecular mechanism of mycobacterial diseases in humans and to the development of new diagnostic and therapeutic approaches to improve care and prognosis. For example, MSMD patients with impaired production of IFN-γ may benefit from injections of human recombinant IFN-γ, while for patients with abolished response to this cytokine, hematopoietic stem cell transplantation (HSCT) and promising gene therapy are the only current therapeutic options. These discoveries also bridge the gap between simple Mendelian inheritance and complex human genetics.

Prevalence of celiac disease in Moroccan children with type 1 diabetes mellitus: A 16-year cross-sectional study.

BACKGROUND: There is limited data available regarding the prevalence of celiac disease (CD) among children with type 1 diabetes mellitus (T1DM) in Arab countries and the Middle East. This cross-sectional study has been designed to explore the prevalence of CD specifically within the population of Moroccan children and adolescents diagnosed with type 1 diabetes mellitus (T1DM). PATIENTS AND METHODS: This is a cross-sectional study of patients who underwent regular follow-up for T1DM at the Pediatric Endocrinology Unit, Abderrahim Harouchi Children's University Hospital in Casablanca, over a 16-year period from 2004 to 2020. Patients were screened for CD by measuring anti-tissue transglutaminase IgA, and those with positive antibodies underwent endoscopy assessment. RESULTS AND DISCUSSION: All 550 patients regularly followed up with TIDM were screened for CD. Fifty-five (33 girls/22 boys) of the screened patients had histologically documented CD, yielding a prevalence of 10%. Nineteen (41.9%) patients had developed CD within the initial four years of diagnosis with T1DM. Therefore, among the six confirmed CD patients, the average age at the onset of T1DM was 3.7 years. For twenty-four (57.5%) of the patients, exhibited no apparent clinical indications of CD, and their condition was only identified through systematic screening. CONCLUSION: This study showed a high prevalence rate of CD associated with type 1 diabetes T1DM, particularly among young children. The results of this paper indicate one of the highest prevalence rates reported in the existing literature for the coexistence of CD and T1DM. These findings may suggest the necessity of a systematic screening of CD in T1DM patients.

Classification of common variable immunodeficiency through immunological and clinical phenotyping in Moroccan patients.

Objective: Common variable immunodeficiency (CVID) is a complex inborn error of humoral immunity with complications of both infectious and non-infectious origins. Classifications of CVID patients provide a clearer understanding of the pathogenesis, prediction, and management of non-infectious complications. This study aims to classify Moroccan CVID patients based on the European classification (EUROclass). Materials and Methods: We recruited 20 CVID patients meeting standard diagnostic criteria (5-6). After collecting clinical and demographic data, we used flow cytometry to analyze B-cell subsets and group patients and assess the relation of each group with clinical manifestations. Results: 90% of the patients in our cohort study had a history of respiratory infections. The noninfectious manifestations included splenomegaly, autoimmunity, lymphadenopathy, and granulomatous diseases diagnosed in 50%, 45%, 40%, and 25% of patients, respectively. We observed significant co-occurrence of splenomegaly with autoimmunity and granulomatous diseases to a lesser extent. Patients had a significant reduction in total, switched memory, marginal zone-like, plasma blasts, and a substantial increase in the percentage of activated B cells, suggesting a defect in the late phases of B-cell differentiation. This condition was linked with an increased occurrence of splenomegaly and granulomatous affections. Besides, patients also had an expansion of CD21low B-cells, which was strongly associated with splenomegaly. Conclusion: The classification of the first Moroccan cohort of CVID patients showed agreement with previous results. It suggests the possibility of adopting this approach on a global scale for better diagnosis and follow-up of CVID patients.

Clinical and Immunological Features of 96 Moroccan Children with SCID Phenotype: Two Decades' Experience.

Severe combined immunodeficiency (SCID) is a heterogeneous group of primary immunodeficiency diseases (PIDs) characterized by a lack of autologous T lymphocytes. This severe PID is rare, but has a higher prevalence in populations with high rates of consanguinity. The epidemiological, clinical, and immunological features of SCIDs in Moroccan patients have never been reported. The aim of this study was to provide a clinical and immunological description of SCID in Morocco and to assess changes in the care of SCID patients over time. This cross-sectional retrospective study included 96 Moroccan patients referred to the national PID reference center at Casablanca Children's Hospital for SCID over two decades, from 1998 to 2019. The case definition for this study was age < 2 years, with a clinical phenotype suggestive of SCID, and lymphopenia, with very low numbers of autologous T cells, according to the IUIS Inborn Errors of Immunity classification. Our sample included 50 male patients, and 66% of the patients were born to consanguineous parents. The median age at onset and diagnosis were 3.3 and 6.5 months, respectively. The clinical manifestations commonly observed in these patients were recurrent respiratory tract infection (82%), chronic diarrhea (69%), oral candidiasis (61%), and failure to thrive (65%). The distribution of SCID phenotypes was as follows: T-B-NK+ in 44.5%, T-B-NK- in 32%, T-B+NK- in 18.5%, and T-B+NK+ in 5%. An Omenn syndrome phenotype was observed in 15 patients. SCID was fatal in 84% in the patients in our cohort, due to the difficulties involved in obtaining urgent access to hematopoietic stem cell transplantation, which, nevertheless, saved 16% of the patients. The autosomal recessive forms of the clinical and immunological phenotypes of SCID, including the T-B-NK+ phenotype in particular, were more frequent than those in Western countries. A marked improvement in the early detection of SCID cases over the last decade was noted. Despite recent progress in SCID diagnosis, additional efforts are required, for genetic confirmation and particularly for HSCT.

A Homozygous RAG1 Gene Mutation in a Case of Combined Immunodeficiency: Clinical, Molecular, and Computational Analysis.

BACKGROUND: The recombination-activating gene 1 and 2 (RAG1/RAG2) proteins are essential to initiate the V(D)J recombination process, the result is a diverse repertoire of antigen receptor genes and the establishment of the adaptive immunity. RAG1 mutations can lead to multiple forms of combined immunodeficiency. METHODS: In this report, whole exome sequencing was performed in a Moroccan child suffering from combined immunodeficiency, with T and B lymphopenia, autoimmune hemolytic anemia, and cytomegalovirus (CMV) infection. RESULTS: After filtering data and Sanger sequencing validation, one homozygous mutation c.2446G>A (p.Gly816Arg) was identified in the RAG1 gene. CONCLUSION: This finding expands the spectrum of immunological and genetic profiles linked to RAG1 mutation, it also illustrates the necessity to consider RAG1 immunodeficiency in the presence of autoimmune hemolytic anemia and CMV infection, even assuming the immunological phenotype appears more or less normal.

Primary Immunodeficiencies: Epidemiology in the Maghreb.

INTRODUCTION: Primary Immunodeficiency (PIDs) is a set of 330 rare hereditary diseases that increase susceptibility to infections, allergies, autoimmunity, and neoplasia. North American registries give higher prevalence than Maghreb ones, whereas consanguinity is high. The purpose of this study is to compare prevalence and coverage rate of Maghreb PID registries with estimates based on USA. METHODS: We searched the prevalence of PIDs in the Maghreb registers. Next, we estimated the expected values based on recent publications. Finally, we calculated the coverage rate of the Maghreb registries compared to the new estimates and we evaluated the impact of consanguinity. RESULTS: The total number is N1 = 2456 patients. The current Maghreb PID Prevalence is 2.56 / 100,000 inhabitants (population of 94,804,694 Million in 2017). Tunisia leads with a prevalence of 8.70 followed by Morocco 2.09, Libya 1.65 and Algeria 1.46/100.000 habitants. We did not find values for Mauritania. If we extrapolate the prevalence of the USA to the Maghreb population, the number of patients in the Maghreb would be N2 = 27,588 and the coverage rate (N1 / N2) would be 8.90%. This low coverage rate is however better than the World average (1.21%), that of Latin America 1.19% and Africa 0.36%. The Maghreb prevalence is close to that of the Arab world 2.04 / 100,000 (population of 391,449,544 in 2017). Using the incidence found in the USA, the number of patients would be 9765 new patients per year in the Maghreb and 40,319 in Arab countries. CONCLUSION: PID Maghreb patients number is very low compared to global estimates, whereas consanguinity is very high. Special attention should be given to PIDs by governments and research teams in this region.

Poikiloderma with Neutropenia in Morocco: a Report of Four Cases.

PURPOSE: Poikiloderma with Neutropenia (PN) is inherited genodermatosis which results from a biallelic mutation in the USB1 gene (U Six Biogenesis 1). PN, first described in Navajo Native Americans, is characterized by early onset poikiloderma, pachyonychia, palmo-plantar hyperkeratosis, and permanent neutropenia. This condition results in frequent respiratory tract infections during infancy and childhood. From 2011 to 2013, four cases of PN were diagnosed in Morocco. In this paper, we report the first four cases of PN diagnosed in Morocco, out of three unrelated consanguinous families. METHODS: We investigated the genetic, immunological, and clinical features of four Moroccan patients with PN from three unrelated consanguinous families. RESULTS: Mean age at onset was 3 months and mean age at diagnosis was 7.5 years. The diagnosis of these PN patients was made based on clinical features and confirmed by molecular analysis for three cases. We identified two undescribed homozygous mutations in the USB1 gene: c.609 + 1G>A in two siblings and c.518 T>G(p.(Leu173Arg)) in the other case. CONCLUSION: This report confirms the clinical and genetic identity of Poikiloderma with Neutropenia syndrome.

X-Linked Agammagobulinemia in a Large Series of North African Patients: Frequency, Clinical Features and Novel BTK Mutations.

PURPOSE: X-linked agammagobulinemia (XLA) is a primary immunodeficiency caused by Bruton's tyrosine kinase (BTK) gene defect. XLA patients have absent or reduced number of peripheral B cells and a profound deficiency in all immunoglobulin isotypes. This multicenter study reports the clinical, immunological and molecular features of Bruton's disease in 40 North African male patients. METHODS: Fifty male out of 63 (male and female) patients diagnosed with serum agammaglobulinemia and non detectable to less than 2% peripheral B cells were enrolled. The search for BTK gene mutations was performed for all of them by genomic DNA amplification and Sanger sequencing. RESULTS: We identified 33 different mutations in the BTK gene in 40 patients including 12 missense mutations, 6 nonsense mutations, 6 splice-site mutations, 5 frameshift, 2 large deletions, one complex mutation and one in-frame deletion. Seventeen of these mutations are novel. This large series shows a lower frequency of XLA among male patients from North Africa with agammaglobulinemia and absent to low B cells compared with other international studies (63.5% vs. 85%). No strong evidence for genotype-phenotype correlation was observed. CONCLUSIONS: This study adds to other reports from highly consanguineous North African populations, showing lower frequency of X-linked forms as compared to AR forms of the same primary immunodeficiency. Furthermore, a large number of novel BTK mutations were identified and could further help identify carriers for genetic counseling.

Chronic granulomatous disease in Morocco: genetic, immunological, and clinical features of 12 patients from 10 kindreds.

PURPOSE: Chronic granulomatous disease (CGD) is characterized by an inability of phagocytes to produce reactive oxygen species (ROS), which are required to kill some microorganisms. CGD patients are known to suffer from recurrent bacterial and/or fungal infections from the first year of life onwards. From 2009 to 2013, 12 cases of CGD were diagnosed in Morocco. We describe here these Moroccan cases of CGD. METHODS: We investigated the genetic, immunological and clinical features of 12 Moroccan patients with CGD from 10 unrelated kindreds. RESULTS: All patients were children suffering from recurrent bacterial and/or fungal infections. All cases displayed impaired NADPH oxidase activity in nitroblue tetrazolium (NBT), dihydrorhodamine (DHR) or 2',7' dichlorofluorescein diacetate (DCFH-DA) assays. Mutation analysis revealed the presence of four different mutations of CYBB in four kindreds, a recurrent mutation of NCF1 in three kindreds, and a new mutation of NCF2 in three patients from a single kindred. A large deletion of CYBB gene has detected in a patient. The causal mutation in the remaining one kindred was not identified. CONCLUSION: The clinical features and infectious agents found in these patients were similar to those in CGD patients from elsewhere. The results of mutation analysis differed between kindreds, revealing a high level of genetic and allelic heterogeneity among Moroccan CGD patients. The small number of patients in our cohort probably reflects a lack of awareness of physicians. Further studies on a large cohort are required to determine the incidence and prevalence of the disease, and to improve the description of the genetic and clinical features of CGD patients in Morocco.

Insights into the genetic theory of infectious diseases.

Over the past century, classical approaches from microbiology and immunology have produced spectacular results in the control of infectious diseases. However, the recent SARS-COV-2 pandemic has highlighted our continued failure to control some infections. Other microorganisms still pose a threat to humanity such as HIV, Ebola, and influenza viruses. It seems that conventional approaches are not able to solve all the current problems caused by infectious diseases. Human genetics has shown that infections have a strong genetic determinism that can lead to a predisposition or resistance to infections. This explains much of the clinical variability observed in individuals infected with the same pathogen. The identification of the genetic etiology allows a better understanding of the pathogenesis of infectious diseases and, consequently, the consideration of appropriate preventive and therapeutic strategies. This review provides insights into the genetic theory and the concrete evidence to support it. We highlight the role of primary immunodeficiencies in the discovery of Mendelian and monogenic susceptibility to infections, then we show how genetic and phenotypic heterogeneity, redundancy, and resistance to infection manifest in the context of this genetic determinism. To effectively combat the constant threat of microbes, it is essential to integrate human genetics with microbiology to examine the interactions between pathogens and our immune system.

An overview of risk factors in children with febrile seizures.

INTRODUCTION: Febrile seizures (FS) are the most common neurologic disorder seen in children. Caused mainly by fever without any damage to the central nervous system (CNS). The associations of several factors, which we can find in the inflammatory response and genetic predisposition, are involved in the occurrence of FS. AIM: This review provides insight into risk factors, particularly the involvement of the inflammatory response and genetic susceptibility in the occurrence of FS. METHODS: A PubMed search was performed using the keywords « febrile seizures ¼, « inflammatory response ¼, « Pro-inflammatory cytokines ¼, «And anti-inflammatory cytokines ¼. The search strategy included meta-analyses, prospective case-control studies, clinical trials, observational studies, and reviews. RESULTS: Febrile seizures with a peak incidence of 18 months usually occur between 6 months and 5 years. A variety of genetic, inflammatory, and environmental factors, including viruses and vaccines, trigger FS. A positive family history of febrile seizures increases the risk for FS occurrence with (20%) in siblings and (33%) in one parent. The involvement of inflammatory response genes, including the cytokine genes IL1B, IL1R, IL6, and IL4. According to these findings, FS is associated with the activation of a cascade of pro- and anti-inflammatory cytokines and the unbalance between these cytokines in the inflammation regulation plays a role in the development of FS. CONCLUSION: Current knowledge suggests that genetic susceptibility and inflammatory response dysregulation contribute to FS's genesis.

Complement system activation: bridging physiology, pathophysiology, and therapy.

The complement system is a set of over 50 proteins that constitutes an essential part of the innate immune system. Complement system activation involves an organized proteolytic cascade. Overactivation of complement system activation is the main pathogenic mechanism of several diseases and contributes to the manifestations of many other conditions. This review describes the normal complement system and the role for complement dysregulation in critical illnesses, notably sepsis and acute respiratory distress syndrome. Complement activation is involved in the immune system response to pathogens but, when excessive, can contribute to tissue damage, runaway inflammation, and capillary leakage syndrome. Complement overactivation may play a key role in severe forms of coronavirus disease 2019 (COVID-19). Two diseases whose manifestations are mainly caused by complement overactivation, namely, atypical hemolytic and uremic syndrome (aHUS) and myasthenia gravis, are discussed. A diagnostic algorithm for aHUS is provided. Early complement-inhibiting therapy has been proven effective. When renal transplantation is required, complement-inhibiting drugs can be used prophylactically to prevent aHUS recurrence. Similarly, acetylcholine-receptor autoantibody-positive generalized myasthenia gravis involves complement system overactivation and responds to complement inhibition. The two main complement inhibitors used in to date routine are eculizumab and ravulizumab. The main adverse event is Neisseria infection, which is rare and preventable, but can be fatal. The complement system is crucial to health but, when overactivated, can cause or contribute to disease. Effective complement inhibitors are now available, although additional data are required to determine optimal regimens. Further research is also needed to better understand the complement system, develop advanced diagnostic tools, and identify markers that allow the personalization of treatment strategies.

Impact of COVID-19 on child tuberculosis hospitalization.

INTRODUCTION: Morocco has made remarkable progress in the fight against tuberculosis, but the Covid-19 pandemic has affected tuberculosis control worldwide, with notable fluctuations in tuberculosis epidemiology during and after the pandemic. AIM: To describe the impact of the Covid-19 pandemic on the rate of hospitalization for tuberculosis and its different localizations in children. METHODS: We conducted a retrospective study based on the analysis of medical records of TB patients hospitalized within the Children's Hospital in Casablanca, during the periods before (2018-2019), during (2020) and after (2021-2022) Covid-19 quarantine. RESULTS: Throughout the study period (2018-2022), the total number of patients hospitalized in our department was 7390, including 283 children were hospitalized for tuberculosis, with a mean age of 6 years. Before the Covid-19 pandemic, the average number of tuberculosis cases was 49 per year, of which the percentage of pulmonary tuberculosis was 32% and extra-pulmonary tuberculosis 68%. The number of cases was 23 per year during the quarantine period, with a percentage of pulmonary tuberculosis of 26% and extra-pulmonary tuberculosis of 74%. After the quarantine period, this number rose to 81 cases per year, of which 21% were pulmonary tuberculosis and 79% extrapulmonary tuberculosis (pleural tuberculosis was predominant in 44.1% of cases). CONCLUSION: These results are consistent with data published by the World Health Organization, and with the findings of another study we carried out on the impact of COVID-19 on hospital admissions for acute lower respiratory tract infections. It is very likely that the reduction in the number of tuberculosis cases during the quarantine period is due to social distancing, which leads to a reduction in the transmission of tuberculosis between people as well as to the disruption of the national tuberculosis control program in Morocco, when positive cases are identified.

Tuberculous Meningitis Genetic predisposition: Understanding cellular interactions, molecular mechanisms and genetic dimensions.

Tuberculous meningitis, a severe form of tuberculosis caused by Mycobacterium tuberculosis (BK), remains a major public health challenge worldwide. In addition to the complex mechanisms of the innate and adaptive immune response against Mycobacterium tuberculosis, there is a crucial genetic dimension to consider. Individuals with specific genetic variations may have altered immune responses that make them more susceptible to this form of tuberculosis. Genetic mutations in genes encoding surface receptors, adaptor proteins, kinases, transcription factors, nucleic receptors and other molecules involved in cellular interactions and molecular mechanisms have been associated with susceptibility to TB. Understanding the molecular mechanisms of immune interactions in host response to Mycobacterium tuberculosis is crucial to understanding the genetic dimension in susceptibility to tuberculosis, particularly its dreaded form of tuberculous meningitis. The aim of this update is to explore in details the key interactions between the main players in innate and adaptive immunity during infection with Mycobacterium tuberculosis, with particular emphasis on the genetic factors associated with susceptibility to tuberculosis, especially its dreaded form of tuberculous meningitis.