Mendelian Susceptibility To Mycobacterial Disease Research Articles

SUCCESSFUL TREATMENT OF INVASIVE MYCOBACTERIUM INFECTION WITH INTERFERON BETA IN A PATIENT WITH INTERFERON-GAMMA RECEPTOR 1 DEFICIENCY

Mendelian susceptibility to mycobacterial disease (MSMD) is caused by approximately 21 genetic defects, including a mutation in Interferon-Gamma Receptor 1 (IFNGR1). IFNGR1 deficiency leads to a loss of cellular responsiveness to type II Interferon (IFN-γ), which plays a significant role in controlling intracellular bacteria. This study explored the response of IFN–β therapy in a patient with partial IFNGR1 deficiency to treat invasive mycobacterial infection. The biological therapy was used successfully as an adjuvant to anti-mycobacterial medications to treat a 17-year-old girl with partial IFNGR1 deficiency who presented with a recurrent mycobacterial infection that extended to her central nervous system, which resulted in clinical and radiological improvement. This report suggests that activation of type I IFN through Signal Transducers and Activators of Transcription1 (STAT1) could bypass the early IFN-γ signaling defects and activate IFN-γ production. For that reason, IFN–β might be used as a beneficial adjuvant therapy for managing extensive central nervous system mycobacterial infection, especially in patients with IFNGR1 deficiency.

Diagnosis and Management of Infections in Patients with Mendelian Susceptibility to Mycobacterial Disease.

The diagnosis and treatment of patients with mendelian susceptibility to mycobacterial disease (MSMD) pose consistent challenges due to the diverse infection spectrum observed in this population. Common clinical manifestations include Bacillus Calmette-Guérin vaccine (BCG) complications in countries where routine BCG vaccination is practiced, while in non-BCG-vaccinating countries, Non-Tuberculous Mycobacteria (NTM) is prevalent. In tuberculosis-endemic regions, Mycobacterium tuberculosis (MTB) has a high prevalence, along with other intracellular organisms. Isolating these organisms presents a significant challenge, and treatment is often initiated without confirming the specific species. This review primarily focuses on the methods and challenges associated with diagnosing and treating MSMD patients.

Recombinant IFN-γ1b Treatment in a Patient with Inherited IFN-γ Deficiency

PurposeInborn errors of IFN-γ immunity underlie Mendelian susceptibility to mycobacterial disease (MSMD). Twenty-two genes with products involved in the production of, or response to, IFN-γ and variants of which underlie MSMD have been identified. However, pathogenic variants of IFNG encoding a defective IFN-γ have been described in only two siblings, who both underwent hematopoietic stem cell transplantation (HCST).MethodsWe characterized a new patient with MSMD by genetic, immunological, and clinical means. Therapeutic decisions were taken on the basis of these findings.ResultsThe patient was born to consanguineous Turkish parents and developed bacillus Calmette-Guérin (BCG) disease following vaccination at birth. Whole-exome sequencing revealed a homozygous private IFNG variant (c.224 T > C, p.F75S). Upon overexpression in recipient cells or constitutive expression in the patient’s cells, the mutant IFN-γ was produced within the cells but was not correctly folded or secreted. The patient was treated for 6 months with two or three antimycobacterial drugs only and then for 30 months with subcutaneous recombinant IFN-γ1b plus two antimycobacterial drugs. Treatment with IFN-γ1b finally normalized all biological parameters. The patient presented no recurrence of mycobacterial disease or other related infectious diseases. The treatment was well tolerated, without the production of detectable autoantibodies against IFN-γ.ConclusionWe describe a patient with a new form of autosomal recessive IFN-γ deficiency, with intracellular, but not extracellular IFN-γ. IFN-γ1b treatment appears to have been beneficial in this patient, with no recurrence of mycobacterial infection over a period of more than 30 months. This targeted treatment provides an alternative to HCST in patients with complete IFN-γ deficiency or at least an option to better control mycobacterial infection prior to HCST.

Genetic, immunologic, and clinical features of 830 patients with Mendelian susceptibility to mycobacterial diseases (MSMD): A systematic review

BackgroundMendelian susceptibility to mycobacterial diseases (MSMD) is a rare clinical syndrome characterized by vulnerability to weakly virulent mycobacterial species, including Bacillus Calmette-Guérin (BCG) vaccines and environmental mycobacteria. ObjectiveWe performed a systematic review of the genetic, immunological, and clinical findings for reported MSMD patients. MethodsWe searched PubMed, Web of Science, and Scopus databases for publications in English relating to MSMD. All full texts were evaluated for eligibility for inclusion. Two reviewers independently selected the publications, with a third reviewer consulted in cases of disagreement. ResultsA primary systematic search and searches of other resources identified 16,155 articles. In total, 158 articles from 63 countries were included in qualitative and quantitative analyses. In total, 830 patients — 436 males (52.5%), 369 females (44.5%), and 25 patients of unknown sex (3.0%) — from 581 families were evaluated. A positive family history was reported in 347 patients (45.5%). The patients had a mean age of 10.41 ± 0.42 (standard error of the mean) years. The frequency of MSMD was highest in Iran, Turkey, and Saudi Arabia. Lymphadenopathy was the most common clinical manifestation of MSMD, reported in 378 (45.5%) cases and multifocal in 35.1%. Fever, organomegaly, and sepsis were the next most frequent findings, reported in 251 (30.2%), 206 (24.8%), and 171 (20.8%) cases, respectively. In total, 299 unique mutations in 21 genes known to be involved in MSMD were reported: 100 missense (34%), 80 indel-frameshift (insertion or deletion, 27%), 53 nonsense (18%), 35 splice site (12%), 10 indel-in frame (2.7%), 6 indel (2%) and 15 large deletion/duplication mutations. Finally, 61% of the reported MSMD patients had mutations of IL12RB1 (41%) or IFNGR1 (20%). At the time of the report, 177 of the patients (21.3%) were dead, and 597 (71.9%) were still alive. ConclusionMSMD is associated with a high mortality rate, mostly due to impaired control of infection. Pre-exposure strategies, such as changes in vaccination policy in endemic areas, the establishment of a worldwide registry of MSMD patients, and precise follow-up over generations in affected families, appear to be vital, to decrease MSMD-related mortality.

Genetic susceptibility to Tuberculosis in an infant with BCG-osis

Mendelian susceptibility to mycobacterial diseases (MSMD) is a group of innate immunity defects characterized by inborn susceptibility to intracellular pathogens. These are due to defects in the interleukin 12-23-interferon gamma y axis. Twenty-three genetic mutations have been identified in this axis, of which mutation in the IL12RB1 gene is the most common genetic defect of MSMD identified. An 11-month-old infant presented with features of axillary lymphadenitis and skin lesions both of which were positive for acid-fast bacilli on Ziehl– Neelsen stain and GeneXpert. Keeping a high index of suspicion of primary immunodeficiency, the child was evaluated further and was diagnosed as a case of MSMD with IL12RB1 gene mutation.

Symposium 11

Autoimmune diseases are conditions of immune dysfunction, leading to inappropriate hyperactivation of the adaptive immunity and subsequent damage to various tissues of the host. Autoimmune conditions presenting in the rheumatology clinics (rheumatoid arthritis, systemic lupus erythematosus or immune mediated myositis) are often treated by immunosuppression, which are almost invariably associated with increased susceptibility to infections. However, immunosuppression can sometimes be used to conversely treat susceptibility to infections. An emerging group of autoimmune diseases which target the host’s own immune system (or associated cytokines) are becoming increasing recognized which phenotypically mimics various immunodeficiency syndromes – known as “phenocopies of PID”. One particular phenocopy of a PID known as Mendelian Susceptibility to Mycobacterial Disease (MSMD) has been increasingly recognized in our locality. This “acquired MSMD” is due to autoantibodies against anti-IFN[Formula: see text], leading to increased susceptibility to mycobacterial and other “IFN-[Formula: see text] dependent” infections. Alike other autoimmune diseases, appropriate and targeted immunosuppression can alleviate the effect of anti-IFN-[Formula: see text] antibodies and aid treatment of associated infections. During this talk, our experience in the diagnosis and management toward acquired MSMD in our locality will be discussed. We will also share findings from our novel diagnostic and functional tests, as well as outcomes of acquired MSMD patients treated with B-cell depleting therapies.

Current management of cervicofacial nontuberculous mycobacterial infections in the pediatric population.

The purpose of this review is to analyze and consolidate recently published literature to provide updated guidelines on the diagnosis and management of nontuberculous mycobacterial lymphadenitis (NTM LAD) in the pediatric population and to suggest areas of further research. Diagnosis of NTM LAD relies on a detailed clinical history, physical examination, laboratory tests, and imaging techniques. Treatment strategies vary widely, with a shift towards complete surgical excision being observed due to its higher cure rate, improved aesthetic outcomes, and lower recurrence rates. However, patient-specific factors must be considered. The role of genetic factors, such as Mendelian susceptibility to mycobacterial disease (MSMD), is being increasingly recognized and could lead to targeted therapies. Despite strides in the understanding and management of NTM LAD, substantial gaps remain in key areas such as the role of diagnostic imaging, optimal treatment parameters, postoperative care, and surveillance strategies. In this article, we explain our approach to NTM using the most relevant evidence-based medicine while offering directions for future work.

A rare mutation causing autosomal dominant STAT1 deficiency in a South African multiplex kindred with disseminated BCG infection

BackgroundAutosomal dominant signal transducer and activator of transcription 1 (STAT1) deficiency, part of the Mendelian susceptibility to mycobacterial disease (MSMD) group, frequently causes disseminated Bacillus Calmette-Guérin (BCG) infections, but has not been reported from Sub-Saharan Africa (SSA) where routine birth BCG vaccination is practiced.Case presentationTwo half-siblings presented five years apart, with multifocal osteomyelitis as the dominant feature of disseminated BCG, which was successfully treated with antimycobacterial therapy. Whole exome sequencing demonstrated a novel heterozygous substitution in the splice site between intron 13 and exon 14 of the STAT1 gene, NM_007315: c.1128-1G>A, in the proband and his mother and was later confirmed in his half-brother.ConclusionsChildren with BCG vaccine complications in SSA should be referred for further investigation and particular consideration of MSMD.

Challenges of Diagnosing Mendelian Susceptibility to Mycobacterial Diseases in South Africa.

Inborn errors of immunity (IEI) are genetic disorders with extensive clinical presentations. They can range from increased susceptibility to infections to significant immune dysregulation that results in immune impairment. While IEI cases are individually rare, they collectively represent a significant burden of disease, especially in developing countries such as South Africa, where infectious diseases like tuberculosis (TB) are endemic. This is particularly alarming considering that certain high penetrance mutations that cause IEI, such as Mendelian Susceptibility to Mycobacterial Disease (MSMD), put individuals at higher risk for developing TB and other mycobacterial diseases. MSMD patients in South Africa often present with different clinical phenotypes than those from the developed world, therefore complicating the identification of disease-associated variants in this setting with a high burden of infectious diseases. The lack of available data, limited resources, as well as variability in clinical phenotype are the reasons many MSMD cases remain undetected or misdiagnosed. This article highlights the challenges in diagnosing MSMD in South Africa and proposes the use of transcriptomic analysis as a means of potentially identifying dysregulated pathways in affected African populations.

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.

Human IL-23 is essential for IFN-γ-dependent immunity to mycobacteria

Patients with autosomal recessive (AR) IL-12p40 or IL-12RB1 deficiency display Mendelian susceptibility to mycobacterial disease (MSMD) due to impaired IFN-g production and, less commonly, chronic mucocutaneous candidiasis (CMC) due to impaired IL-17A/F production. We report six patients from four unrelated kindreds with AR IL-23R deficiency. All six patients have a history of MSMD but only two suffered from CMC. The four IL23R variants are associated with IL-23R loss of function, both in an isogenic overexpression assay and in the patients’ derived cells. We observe that IL-23R deficiency impairs baseline IFN-g immunity in at least 19 leukocyte subsets, including lymphoid and myeloid subsets, in vivo, without affecting their development per se. After IL-23 stimulation, we observe IFN-g induction in innate-like adaptive (MAIT, Vd2+ gd T) and innate (NK) lymphocytes in healthy controls but not in IL-23R-deficient patients, suggesting that IL-23 act as an early IFN-g-inducing cytokine in these cells, which, in turn, induce IFN-g-dependent transcriptional programs in both lymphoid and myeloid leukocyte subsets. Upon mycobacterial infection ex vivo, we find impaired IFN-g production by IL-23R-deficient MAIT and Vd2+ gd T cells, and to a lower extend in IL-23R-deficient CD4+ T cells. IL-23 is thus required for both baseline and Mycobacterium-inducible IFN-g immunity in at least MAIT and Vd2+ gd T cells, probably contributing to the complete penetrance of MSMD in IL-23R-deficient patients. MAIT cells from IL-23R-deficient patients display impaired IL-17A induction upon IL-23 stimulation, and PBMCs from IL-23R-deficient patients display impaired IL-17A/F production in response to heat-killed C. albicans, probably accounting for their risk of CMC. We observe normal development of Mycobacterium- and C. albicans-specific CD4+ memory T cells in IL-23R-deficient patients, possibly accounting for the absence of mycobacterial disease recurrence and the incomplete penetrance of CMC in these patients, respectively. Overall, our findings suggest that human IL-12 and IL-23 are functionally more closely related, via their induction of IFN-g, than previously thought based on the classical TH1/TH17 paradigm established in mice. They further suggest that the mechanisms underlying the therapeutic efficacy of IL-23p19 blockers may involve an inhibition, not only of excessive IL-17 immunity, but also of excessive IFN-g immunity.

Autosomal recessive T-bet and RORgammaT deficiencies underlie mycobacterial susceptibility

Mendelian susceptibility to mycobacterial disease (MSMD) is characterized by selective, inherited predisposition to clinical disease caused by weakly virulent mycobacteria, such as M.bovis BCG vaccines and environmental mycobacteria (EM). Twenty MSMD-causing genes have been identified. Their mutations affect IFN-γ-related immune circuits by impairing either the production of, the cellular response to IFN-γ, or both. T-bet and RORγT are transcription factors that govern the lineage commitment of two different T helper lineages, TH1 and TH17 cells, respectively, in mice. Surprisingly, both autosomal recessive (AR) T-bet and RORγT deficiencies in humans underlie mycobacterial susceptibility. Here we summarize the molecular, cellular, and clinical features of a recently identified patient with AR T-bet deficiency and three new patients with AR RORγT deficiency. Human AR T-bet deficiency underlies mycobacterial disease by preventing the development of innate (NK) and innate-like adaptive lymphocytes (iNKT, MAIT, and Vδ2+ γST cells) as well as IFN-γ produced by them. It also underlies peripheral eosinophilia and recurrent upper respiratory inflammation due to excessive production of TH2 cytokines, particularly IL-5 and IL-13, by CD4+ αβT cells. Although humoral immunity in inherited T-bet deficiency remains grossly intact, T-bet is required for the in vivo and in vitro development of a distinct subset of human B cells in humans resembling murine “age-associated B cells” that are associated with infection and autoimmunity. We also identified three new patients with AR RORγT deficiency that underlies both mycobacterial and fungal susceptibility. Inherited RORyT deficiency abolishes the development of iNKT and MAIT cells, two IFN-γ-producing innate-like adaptive T cell subsets, and impairs the production of IFN-γ by Vδ2+ γδT cells in response to mycobacterial stimulation. The production of IFN-γ by purely adaptive apT cells remains largely intact upon mycobacterium-specific stimulation. The development of TH17 cells and the production of TH17 cytokines are abolished in inherited RORyT deficiency, thereby underlying susceptibility to C.albicans. Collectively, impaired development of and defective production of IFN-γ by MAIT, V82+ γ8T cells, and iNKT cells are sufficient to cause mycobacterial susceptibility, whereas the contribution of purely adaptive apT cells to antimycobacterial immunity, at least against M.bovis BCG or EM, is probably inconsequential.Table 1(abstract: 257) ML-model Scores for IEI Test Cohort Baseline vs. Enhanced Model/Manual vs. Automated Term Extractioncase_dxscore_bn36_manualscore_bn47_update_manualscore_change_expertPrediction_Expert_BN36score_bn36_automaticscore_bn47_update_automaticscore_bn_change_HPOPrediction_HPO_BN36CVID0.991.000.0111.001.000.001SIgAD0.060.880.8210.140.690.551AT0.891.000.1110.020.110.090Hypogam0.541.000.4610.040.960.920Hypogam1.001.000.0011.001.000.001AT0.101.000.9011.001.000.001THIG0.020.690.6700.170.840.671CVID vs. Hypogam0.030.900.8701.001.000.001DGS0.541.000.4610.330.930.601DGS0.451.000.5510.380.990.611CVID-common variable immunodeficiency, SIgAD-selective IgA deficiency, AT-ataxia telangiectasia, Hypogam-hypogammaglobulinemia, THIG-transient hypogammaglobulinemia of infancy, DGS-Digeorge SyndromeTable 2(abstract: 257) Full feature set and frequency comparision by term extraction method.ConceptManualAutomated HPOBarnard Exact p_valueimm_dx_test0.70.30.06care_team0.60naMeds0.50naFatigue0.40.60.26iei_dz_mention0.40.4nasn_jiearing_loss0.30naAbscess0.20.10.34iei_gene_mention0.20naclin_care0.20naexam_findings0.20.7***0.021lymphoma0.20.2Napna_fewer_two0.20.40.26pna_greater_two0.20.11thrombocytopenia0.20.2naopportunistic infection0.20.2nahypocalcemia0.20.11Ataxia0.20narec_fever0.20naother_infect0.20.50.11FTT0.10.6***0.011Otorrhea0.10nalymphadenopathy0.10.40.076dysmorphic_feat0.10.1naWarts0.10naSepsis0.10nasinusitis_greater_four0.10nafe_def0.10.20.34lymphopenia0.10.30.16neutropenia0.10.20.34mycobact_dz0.10namycosis_superficial0.10nainv_herpes_dz0.10nagranuloma_skin0.10naaspergillosis0.10naChemo0.10nametabolics0.10.1napolyarthritis0.00naorganomegaly0.00.3naseptic_shock0.00nahyper-eos0.00.1nameningococcal_dz0.00naSle0.00.1nabronchiectasis0.00.1napulm_fibrosis0.00naAiha0.00naencephalitis0.00naheme_manifestation0.00.4na***denotes significant difference at a type I error rate of 0.05 [Display omitted]

HSV-1 and HHV-6 Meningoencephalitis in a Child with STAT1 Mutation

Introduction: STAT1 is a critical signal transducer for both the interferon gamma receptor and IFN-alpha/beta receptors and is required for responses to herpesviruses. STAT1 defects vary in severity and clinical presentation. STAT1 loss of function (LOF) mutations with Mendelian Susceptibility to Mycobacterial Disease (MSMD) and STAT1 gain of function (GOF) mutations have been described with a wide clinical spectrum, including nontuberculous mycobacteria, disseminated fungal, bacterial, and viral infections in addition to immune dysregulation. We present a 10-year-old female with HSV-1 and HHV-6 meningoencephalitis that was found to have a variant in STAT1. MethodsRetrospective chart review was conducted. Laboratory investigations included lymphocyte immunophenotyping by flow cytometry, lymphocyte proliferation to mitogens and antigens, NK cell functional assays, quantitative immunoglobulins, toll like receptor function defects, genetic evaluation by next generation sequencing, and assays for further evaluation for MSMD, T helper IL17, STAT GOF. ResultsA previously healthy 10-year-old Caucasian female presented with fever, headache, and new-onset seizure with status epilepticus. She was diagnosed with HSV-1 and HHV-6 meningoencephalitis, as CSF PCR panel was positive for HSV-1 and HHV-6. Brain MRI showed findings compatible with HSV-1 encephalitis. She was treated with a 14-day course of acyclovir with no noted neurological sequelae. Infection history was unremarkable except for one episode of otitis media as a child and a couple upper respiratory viral illnesses. Denied prior history of HSV infection. No family history of immunodeficiency disorders. Both parents reported remote history of herpetic gingivostomatitis. Laboratory immune evaluation was remarkable for decreased lymphocyte proliferative response to Candida antigen. Next generation sequencing revealed a variant of uncertain significance in STAT1 (c.295A>G; p.Ile99Val) and did not detect TLR3 or UNC93B1 mutations. ConclusionThe clinical phenotype caused by STAT1 mutations is highly diverse, and there is overlap between GOF and LOF phenotypes, making it difficult to clinically diagnose. Although HSV gingivostomatitis has been reported in a patient with STAT1 GOF, invasive disease, such as meningoencephalitis, has not been reported in those with variants in STAT1.

Human IL-23 is essential for IFN-γ-dependent immunity to mycobacteria.

Patients with autosomal recessive (AR) IL-12p40 or IL-12Rβ1 deficiency display Mendelian susceptibility to mycobacterial disease (MSMD) due to impaired IFN-γ production and, less commonly, chronic mucocutaneous candidiasis (CMC) due to impaired IL-17A/F production. We report six patients from four kindreds with AR IL-23R deficiency. These patients are homozygous for one of four different loss-of-function IL23R variants. All six patients have a history of MSMD, but only two suffered from CMC. We show that IL-23 induces IL-17A only in MAIT cells, possibly contributing to the incomplete penetrance of CMC in patients unresponsive to IL-23. By contrast, IL-23 is required for both baseline and Mycobacterium-inducible IFN-γ immunity in both Vδ2+ γδ T and MAIT cells, probably contributing to the higher penetrance of MSMD in these patients. Human IL-23 appears to contribute to IL-17A/F-dependent immunity to Candida in a single lymphocyte subset but is required for IFN-γ-dependent immunity to Mycobacterium in at least two lymphocyte subsets.

Exploration biologique des susceptibilités aux mycobactéries

AbstractMycobacterial infectious diseases include tuberculosis, caused by Mycobacterium tuberculosis, and other less virulent, such as the bacille Calmette-Guérin (BCG) vaccine, or environmental mycobacteria (EM). Mendelian susceptibility to mycobacterial disease (MSMD) is characterized by clinical disease caused by BCG or EM, and implies a defect in the interferon-γ mediated immunity. This cytokine plays an important role between infected phagocytes, and T and NK cells. The in-depth clinical history of the patient, providing information on his family history, as well as a hierarchical immunological exploration, make it possible to differentiate MSMD from other inborn errors of immunity. Thus, the biologist will be able to adopt the best strategy for the immunological, genetic and molecular studies of these patients, proposed by a few reference centers including research laboratory. For the clinician, the identification of a genetic disease will facilitate therapeutic decisions, and will make it possible to provide an appropriate genetic counseling.

Clinical and Genetic Characteristics of BCG Disease in Chinese Children: a Retrospective Study.

Summarize the characteristics of a large cohort of BCG disease and compare differences in clinical characteristics and outcomes among different genotypes and between primary immunodeficiency disease (PID) and patients without identified genetic etiology. We collected information on patients with BCG disease in our center from January 2015 to December 2020 and divided them into four groups: chronic granulomatous disease (CGD), Mendelian susceptibility to mycobacterial disease (MSMD), severe combined immunodeficiency disease (SCID), and gene negative group. A total of 134 patients were reviewed, and most of them had PID. A total of 111 (82.8%) patients had 18 different types of pathogenic gene mutations, most of whom (91.0%) were classified with CGD, MSMD, and SCID. CYBB was the most common gene mutation (52/111). BCG disease behaves differently in individuals with different PIDs. Significant differences in sex (P < 0.001), age at diagnosis (P = 0.013), frequency of recurrent fever (P = 0.007), and vaccination-homolateral axillary lymph node enlargement (P = 0.039) and infection severity (P = 0.006) were noted among the four groups. The CGD group had the highest rate of males and the oldest age at diagnosis. The MSMD group had the highest probability of disseminated infection (48.3%). The course of anti-tuberculosis treatment and the survival time between patients with PID and without identified genetic etiology were similar. Greater than 80% of BCG patients have PID; accordingly, gene sequencing should be performed in patients with BCG disease for early diagnosis. BCG disease behaves differently in patients with different types of PID. Patients without identified genetic etiology had similar outcomes to PID patients, which hints that they may have pathogenic gene mutations that need to be discovered.

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

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. 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. Our study involved 22 cases from 15 unrelated Moroccan kindreds. The average age at diagnosis is 4years. 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. 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.

Analysis of IFN-γR1 (CD119) and IL-12Rβ1 (CD212) Deficiency by Flow Cytometry

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare primary immune deficiency (PID). IL-12Rβ1 deficiency is the most frequently observed of more than 16 genetic defects that have been identified for MSMD. Genetic and immunological tests are remarkable in the diagnosis of PID. In this study, it was aimed to determine the expression of IFN-γR1 and IL-12Rβ1 in patients with MSMD, their relatives, and healthy individuals and to evaluate the importance of flow cytometry as a fast and reliable method in the diagnosis of MSMD. IFN-γR1 and IL-12Rβ1 expression levels were analyzed in 32 volunteers including six patients, six relatives, and 20 healthy individuals. The normal range of IFN-γR1 and IL-12Rβ1 levels among healthy individuals were determined. IL-12Rβ1 expression level in lymphocytes was found to be low in one patient's relative, and less than 1% in three patients and in one patient's relative. It was observed that the IL-12Rβ1 expression levels of the patient with STAT1 deficiency were increased compared to the healthy individuals. No difference was found in the expression levels of IFN-γR1 and IL-12Rβ1 in one patient, but IFN-γR1 expression was decreased in one patient compared to healthy individuals. Our results show that the determination of IL-12Rβ1 and IFN-γR1 deficiencies by flow cytometry can be used as a rapid and reliable method for the diagnosis of MSMD. The use of this method as a screening test will enable early diagnosis especially in patients whose genetic diagnosis has not been confirmed and clinically compatible with MSMD. In addition, it is thought that IL-12Rβ1 and IFN-γR1 range data obtained from healthy individuals will be considered as a reference source in routine and research studies to be conducted with MSMD.

B DISCERNING: ROLE OF RITUXIMAB IN INTERFERON GAMMA AUTOANTIBODY DISEASE

<h3>Introduction</h3> Adult-onset immunodeficiency with anti-interferon gamma autoantibodies can lead to disseminated infections by opportunistic pathogens. This case describes interferon gamma autoantibodies responsible for treatment resistant disseminated mycobacterium avium (MAC) infection. <h3>Case Description</h3> A 52 year-old man originally from Laos was seen as an outpatient consult for concern for immunodeficiency. He originally presented with weight loss and fatigue, and CT chest showed a spiculated mass with lymphadenopathy. Lymph node biopsy demonstrated MAC, and PET scan suggested multi-organ disease. He failed to improve on standard antimicrobial therapy, requiring prolonged hospitalization. Family history was significant for parental consanguinity and a sister with severe MAC infection. Our differential diagnosis included Mendelian susceptibility to mycobacterial disease (MSMD) and acquired interferon-gamma autoantibodies. Genetic testing with the Invitae Primary Immunodeficiency panel was unrevealing, and testing for clinically significant interferon gamma autoantibodies was positive. Due to further clinical deterioration, treatment with rituximab was initiated. His symptoms improved after four weekly infusions with complete depletion of B cells. Despite clinical improvement, he was re-admitted for AKI and hypercalcemia resistant to standard management. His hypercalcemia was ultimately attributed to immune reconstitution inflammatory syndrome (IRIS) due to granulomatous MAC formations. <h3>Discussion</h3> Severe MAC infections are rare and should bring to mind both Mendelian susceptibility to mycobacterial disease and acquired autoantibodies directed against interferon gamma. Rituximab therapy should be considered for patients with auto-antibodies who do not respond to antimicrobial therapy. A potential consequence of such therapy is hypercalcemia secondary to immune reconstitution inflammatory syndrome.

A novel STAT1 loss-of-function mutation associated with Mendelian susceptibility to mycobacterial disease.

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare congenital immune deficiency characterized by susceptibility to weakly virulent mycobacteria. Loss-of-function (LOF) mutation of signal transducer and activator of transcription 1 (STAT1) is one of the common genetic causes of MSMD. In this study, we identified a patient who presented with multiple lymph node enlargements and multiple osteolytic disruptions. Mycobacterium gordonae infection was confirmed by metagenomic next-generation sequencing. Whole-exome sequencing identified a novel paternal heterozygous mutation in exon 22 of STAT1 (NM_007315.4, c.1892T>C, p.Val631Ala). This variant was confirmed pathogenic by multiple software predictions. Based on functional assays, STAT1 expression in STAT1V631A cells was not different from STAT1WT cells. But STAT1V631A mutation caused much lower activation of STAT1 when stimulated by interferon-γ (IFN-γ). Fluorescence localization analysis revealed that both STAT1V631A and STAT1WT proteins were located in the cytoplasm, and only a few STAT1V631A proteins were translocated to the nucleus in response to IFN-γ. These results suggest that STAT1V631A leads to LOF in IFN-γ-mediated mycobacterial immunity, resulting in MSMD. Treatment with antibiotics has achieved ideal disease control for this patient, and no adverse events occurred during follow-up. The STAT1 LOF deficiency is a genetic cause of MSMD, which should be considered in patients with mycobacterial disease, especially those with bone involvement.