EDA-ID and IP, two faces of the same coin: how the same IKBKG/NEMO mutation affecting the NF-κB pathway can cause immunodeficiency and/or inflammation

A Novel Ectodysplasin a Gene mutation of X-Linked Hypohidrotic Ectodermal Dysplasia

Introduction

Hypohidrotic ectodermal dysplasia (HED) is a genetic disorder that influences structures of ectodermal origin, such as teeth, hair, and sweat glands. Compared with autosomal recessive and dominant modes of inheritance, the X-linked HED (XLHED) characterized by Hypodontia/Oligodontia teeth, Absent/sparse hair, Anhidrosis/hypohidrosis, and characteristic facial features, is the most frequent and its primary cause is the mutation of ectodysplasin A (EDA) gene. This research aimed to expound the clinical and molecular features of a Chinese male with XLHED and to summarize and compare several previous findings.

Methods

Genomic DNA was obtained from the peripheral blood of the proband and his family members, then Sanger sequencing was used to perform a mutational analysis of EDA. Real-time quantitative PCR and Western blotting were used to detect EDA expression. The transcriptional activity of NF-κB was detected using a luciferase assay.

Results

The probandwith XLHED was identified a novel EDA mutation, c.1119G>C(p.M373I), that affected the molecular analysis of transmembrane protein exon8 mutations, inherited from the mother. He showed a severe multiple-tooth loss, with over 20 permanent teeth missing and sparse hair and eyebrows, dry, thin, and itching skin. Furthermore, his sweating function was abnormal to a certain extent.

Discussion

The functional study showed that this novel mutant led to a significant decrease in the EDA expression level and transcriptional activity of NF-κB. Our findings extend the range of EDA mutations in XLHED patients, which provides the basis and idea for further exploring the pathogenesis of XLHED.

Identification of crucial inflammaging related risk factors in multiple sclerosis

Background

Multiple sclerosis (MS) is an immune-mediated disease characterized by inflammatory demyelinating lesions in the central nervous system. Studies have shown that the inflammation is vital to both the onset and progression of MS, where aging plays a key role in it. However, the potential mechanisms on how aging-related inflammation (inflammaging) promotes MS have not been fully understood. Therefore, there is an urgent need to integrate the underlying mechanisms between inflammaging and MS, where meaningful prediction models are needed.

Methods

First, both aging and disease models were developed using machine learning methods, respectively. Then, an integrated inflammaging model was used to identify relative risk factors, by identifying essential "aging-inflammation-disease" triples. Finally, a series of bioinformatics analyses (including network analysis, enrichment analysis, sensitivity analysis, and pan-cancer analysis) were further used to explore the potential mechanisms between inflammaging and MS.

Results

A series of risk factors were identified, such as the protein homeostasis, cellular homeostasis, neurodevelopment and energy metabolism. The inflammaging indices were further validated in different cancer types. Therefore, various risk factors were integrated, and even both the theories of inflammaging and immunosenescence were further confirmed.

Conclusion

In conclusion, our study systematically investigated the potential relationships between inflammaging and MS through a series of computational approaches, and could present a novel thought for other aging-related diseases.

AZD1390, an ataxia telangiectasia mutated inhibitor, attenuates microglia-mediated neuroinflammation and ischemic brain injury

AIMS

Excessive neuroinflammation mediated mainly by microglia plays a crucial role in ischemic stroke. AZD1390, an ataxia telangiectasia mutated (ATM) specific inhibitor, has been shown to promote radio-sensitization and survival in central nervous system malignancies, while the role of AZD1390 in ischemic stroke remains unknown.

METHODS

Real-time PCR, western blot, immunofluorescence staining, flow cytometry and enzyme-linked immunosorbent assays were used to assess the activation of microglia and the release of inflammatory cytokines. Behavioral tests were performed to measure neurological deficits. 2,3,5-Triphenyltetrazolium chloride staining was conducted to assess the infarct volume. The activation of NF-κB signaling pathway was explored through immunofluorescence staining, western blot, co-immunoprecipitation and proximity ligation assay.

RESULTS

The level of pro-inflammation cytokines and activation of NF-κB signaling pathway was suppressed by AZD1390 in vitro and in vivo. The behavior deficits and infarct size were partially restored with AZD1390 treatment in experimental stroke. AZD1390 restrict ubiquitylation and sumoylation of the essential regulatory subunit of NF-κB (NEMO) in an ATM-dependent and ATM-independent way respectively, which reduced the activation of the NF-κB pathway.

CONCLUSION

AZD1390 suppressed NF-κB signaling pathway to alleviate ischemic brain injury in experimental stroke, and attenuated microglia activation and neuroinflammation, which indicated that AZD1390 might be an attractive agent for the treatment of ischemic stroke.

NF-κB Signaling is Required for X-Chromosome Inactivation Maintenance Following T cell Activation

X Chromosome Inactivation (XCI) is a female-specific process which balances X-linked gene dosage between sexes. Unstimulated T cells lack cytological enrichment of Xist RNA and heterochromatic modifications on the inactive X chromosome (Xi), and these modifications become enriched at the Xi after cell stimulation. Here, we examined allele-specific gene expression and the epigenomic profiles of the Xi following T cell stimulation. We found that the Xi in unstimulated T cells is largely dosage compensated and is enriched with the repressive H3K27me3 modification, but not the H2AK119-ubiquitin (Ub) mark, even at promoters of XCI escape genes. Upon CD3/CD28-mediated T cell stimulation, the Xi accumulates H2AK119-Ub and H3K27me3 across the Xi. Next, we examined the T cell signaling pathways responsible for Xist RNA localization to the Xi and found that T cell receptor (TCR) engagement, specifically NF-κB signaling downstream of TCR, is required. Disruption of NF-κB signaling, using inhibitors or genetic deletions, in mice and patients with immunodeficiencies prevents Xist/XIST RNA accumulation at the Xi and alters expression of some X-linked genes. Our findings reveal a novel connection between NF-κB signaling pathways which impact XCI maintenance in female T cells.

Role of Skewed X-Chromosome Inactivation in Common Variable Immunodeficiency

The term common variable immunodeficiency (CVID) encompasses a clinically diverse group of disorders, mainly characterized by hypogammaglobulinemia, insufficient specific antibody production, and recurrent infections. The genetics of CVID is complex, and monogenic defects account for only a portion of cases, typically <30%. Other proposed mechanisms include digenic, oligogenic, or polygenic inheritance and epigenetic dysregulation. In this study, we aimed to assess the role of skewed X-chromosome inactivation (XCI) in CVID. Within our cohort of 131 genetically analyzed CVID patients, we selected female patients with rare variants in CVID-associated genes located on the X-chromosome. Four patients harboring heterozygous variants in BTK (n = 2), CD40LG (n = 1), and IKBKG (n = 1) were included in the study. We assessed XCI status using the HUMARA assay and an NGS-based method to quantify the expression of the 2 alleles in mRNA. Three of the 4 patients (75%) exhibited skewed XCI, and the mutated allele was predominantly expressed in all cases. Patient 1 harbored a hypomorphic variant in BTK (p.Tyr418His), patient 3 had a pathogenic variant in CD40LG (c.288+1G>A), and patient 4 had a hypomorphic variant in IKBKG (p.Glu57Lys) and a heterozygous splice variant in TNFRSF13B (TACI) (c.61+2T>A). Overall, the analysis of our cohort suggests that CVID in a small proportion of females (1.6% in our cohort) is caused by skewed XCI and highly penetrant gene variants on the X-chromosome. Additionally, skewed XCI may contribute to polygenic effects (3.3% in our cohort). These results indicate that skewed XCI may represent another piece in the complex puzzle of CVID genetics.

NEMO reshapes the α-Synuclein aggregate interface and acts as an autophagy adapter by co-condensation with p62

NEMO is a ubiquitin-binding protein which regulates canonical NF-κB pathway activation in innate immune signaling, cell death regulation and host-pathogen interactions. Here we identify an NF-κB-independent function of NEMO in proteostasis regulation by promoting autophagosomal clearance of protein aggregates. NEMO-deficient cells accumulate misfolded proteins upon proteotoxic stress and are vulnerable to proteostasis challenges. Moreover, a patient with a mutation in the NEMO-encoding IKBKG gene resulting in defective binding of NEMO to linear ubiquitin chains, developed a widespread mixed brain proteinopathy, including α-synuclein, tau and TDP-43 pathology. NEMO amplifies linear ubiquitylation at α-synuclein aggregates and promotes the local concentration of p62 into foci. In vitro, NEMO lowers the threshold concentrations required for ubiquitin-dependent phase transition of p62. In summary, NEMO reshapes the aggregate surface for efficient autophagosomal clearance by providing a mobile phase at the aggregate interphase favoring co-condensation with p62.

Inborn errors of immunity underlying defective T-cell memory

PURPOSE OF REVIEW

T-cell memory is a complex process not well understood involving specific steps, pathways and different T-cell subpopulations. Inborn errors of immunity (IEIs) represent unique models to decipher some of these requirements in humans. More than 500 different IEIs have been reported to date, and recently a subgroup of monogenic disorders characterized by memory T-cell defects has emerged, providing novel insights into the pathways of T-cell memory generation and maintenance, although this new knowledge is mostly restricted to peripheral blood T-cell memory populations.

RECENT FINDINGS

This review draws up an inventory of the main and recent IEIs associated with T-cell memory defects and their mice models, with a particular focus on the nuclear factor kappa B (NF-κB) signalling pathway, including the scaffold protein capping protein regulator and myosin 1 linker 2 (CARMIL2) and the T-cell co-stimulatory molecules CD28 and OX-40. Besides NF-κB, IKZF1 (IKAROS), a key transcription factor of haematopoiesis and STAT3-dependent interleukin-6 signals involving the transcription factor ZNF341 also appear to be important for the generation of T cell memory. Somatic reversion mosaicism in memory T cells is documented for several gene defects supporting the critical role of these factors in the development of memory T cells with a potential clinical benefit.

SUMMARY

Systematic examination of T-cell memory subsets could be helpful in the diagnosis of IEIs.

An Atypical Incontinentia Pigmenti Female with Persistent Mucocutaneous Hyperinflammation and Immunodeficiency Caused by a Novel Germline IKBKG Missense Mutation

While most missense mutations of the IKBKG gene typically result in Ectodermal Dysplasia with Immunodeficiency, there have been rare reported instances of missense mutations of the IKBKG gene causing both Incontinentia Pigmenti (IP) and immunodeficiency in female patients. In this study, we described an atypical IP case in a 19-year-old girl, characterized by hyperpigmented and verrucous skin areas over the entire body. Remarkably, she experienced recurrent red papules whenever she had a feverish upper respiratory tract infection. Immunohistochemical staining unveiled a substantial accumulation of CD68+ macrophages alongside the TNF-α positive cells in the dermis tissue of new pustules, with increased apoptotic basal keratinocytes in the epidermis tissue of these lesions. Starting from the age of 8 years old, the patient suffered from severe and sustained chronic respiratory mucous membrane scar hyperplasia and occluded subglottic lumen. In addition to elevated erythrocyte sedimentation rate values, inflammatory cells were observed in the pathologic lesions of endobronchial biopsies and Bronchoalveolar Lavage Fluid (BALF) smear. Further histological analysis revealed a destructive bronchus epithelium integrity with extensive necrosis. Simultaneously, the patient experienced recurrent incomplete intestinal obstructions and lips contracture. The patient's BALF sample displayed an augmented profile of proinflammatory cytokines and chemokines, suggesting a potential link to systemic hyperinflammation, possibly underlying the pathogenic injuries affecting the subglottic, respiratory, and digestive systems. Furthermore, the patient presented with recurrent pneumonias and multiple warts accompanied by a T+BlowNKlow immunophenotype. Next generation sequencing showed that the patient carried a novel de novo germline heterozygous missense mutation in the IKBKG gene (c. 821T>C, p. L274P), located in the highly conserved CC2 domain. TA-cloning sequencing of patient's cDNA yielded 30 mutant transcripts out of 44 clones. In silico analysis indicated that the hydrogen bond present between Ala270 and Leu274 in the wild-type NEMO was disrupted by the Leu274Pro mutation. However, this mutation did not affect NEMO expression in peripheral blood mononuclear cells (PBMCs). Moreover, patient PBMCs exhibited significantly impaired TNF-α production following Lipopolysaccharide (LPS) stimulation. X-chromosome inactivation in T cells and neutrophils were not severely skewed. Reduced levels of IκBα phosphorylation and degradation in patient's PBMCs were observed. The NF-κB luciferase reporter assay conducted using IKBKG-deficient HEK293T cells revealed a significant reduction in NF-kB activity upon LPS stimulation. These findings adds to the ever-growing knowledge on female IP that might contribute to the better understanding of this challenging disorder.

Linear ubiquitination induces NEMO phase separation to activate NF-κB signaling

The NF-κB essential modulator NEMO is the core regulatory component of the inhibitor of κB kinase complex, which is a critical checkpoint in canonical NF-κB signaling downstream of innate and adaptive immune receptors. In response to various stimuli, such as TNF or IL-1β, NEMO binds to linear or M1-linked ubiquitin chains generated by LUBAC, promoting its oligomerization and subsequent activation of the associated kinases. Here we show that M1-ubiquitin chains induce phase separation of NEMO and the formation of NEMO assemblies in cells after exposure to IL-1β. Phase separation is promoted by both binding of NEMO to linear ubiquitin chains and covalent linkage of M1-ubiquitin to NEMO and is essential but not sufficient for its phase separation. Supporting the functional relevance of NEMO phase separation in signaling, a pathogenic NEMO mutant, which is impaired in both binding and linkage to linear ubiquitin chains, does not undergo phase separation and is defective in mediating IL-1β-induced NF-κB activation.

Pharmacologic Management of Monogenic and Very Early Onset Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) is treated with a variety of immunomodulating and immunosuppressive therapies; however, for the majority of cases, these therapies are not targeted for specific disease phenotypes. Monogenic IBD with causative genetic defect is the exception and represents a disease cohort where precision therapeutics can be applied. With the advent of rapid genetic sequencing platforms, these monogenic immunodeficiencies that cause inflammatory bowel disease are increasingly being identified. This subpopulation of IBD called very early onset inflammatory bowel disease (VEO-IBD) is defined by an age of onset of less than six years of age. Twenty percent of VEO-IBDs have an identifiable monogenic defect. The culprit genes are often involved in pro-inflammatory immune pathways, which represent potential avenues for targeted pharmacologic treatments. This review will provide an overview of the current state of disease-specific targeted therapies, as well as empiric treatment for undifferentiated causes of VEO-IBD.

Infections in Inborn Errors of Immunity with Combined Immune Deficiency: A Review

Enhanced susceptibility to microbes, often resulting in severe, intractable and frequent infections due to usually innocuous organisms at uncommon sites, is the most striking feature in individuals with an inborn error of immunity. In this narrative review, based on the International Union of Immunological Societies' 2022 (IUIS 2022) Update on phenotypic classification of human inborn errors of immunity, the focus is on commonly encountered Combined Immunodeficiency Disorders (CIDs) with susceptibility to infections. Combined immune deficiency disorders are usually commensurate with survival beyond infancy unlike Severe Combined Immune Deficiency (SCID) and are often associated with clinical features of a syndromic nature. Defective humoral and cellular immune responses result in susceptibility to a broad range of microbial infections. Although disease onset is usually in early childhood, mild defects may present in late childhood or even in adulthood. A precise diagnosis is imperative not only for determining management strategies, but also for providing accurate genetic counseling, including prenatal diagnosis, and also in deciding empiric treatment of infections upfront before investigation reports are available.

Uncovering incontinentia pigmenti: From DNA sequence to pathophysiology

Incontinentia pigmenti (IP) is an X-linked dominant genodermatosis. The disease is known to be caused by recurrent deletion of exons 4-10 of the Inhibitor Of Nuclear Factor Kappa B Kinase Regulatory Subunit Gamma (IKBKG) gene located at the Xq28 chromosomal region, which encodes for NEMO/IKKgamma, a regulatory protein involved in the nuclear factor kappa B (NF-κB) signaling pathway. NF-κB plays a prominent role in the modulation of cellular proliferation, apoptosis, and inflammation. IKBKG mutation that results in a loss-of-function or dysregulated NF-κB pathway contributes to the pathophysiology of IP. Aside from typical skin characteristics such as blistering rash and wart-like skin growth presented in IP patients, other clinical manifestations like central nervous system (CNS) and ocular anomalies have also been detected. To date, the clinical genotype-phenotype correlation remains unclear due to its highly variable phenotypic expressivity. Thus, genetic findings remain an essential tool in diagnosing IP, and understanding its genetic profile allows a greater possibility for personalized treatment. IP is slowly and gradually gaining attention in research, but there is much that remains to be understood. This review highlights the progress that has been made in IP including the different types of mutations detected in various populations, current diagnostic strategies, IKBKG pathophysiology, genotype-phenotype correlation, and treatment strategies, which provide insights into understanding this rare mendelian disorder.

IKKγ/NEMO Localization into Multivesicular Bodies

The NF-κB pathway is central pathway for inflammatory and immune responses, and IKKγ/NEMO is essential for NF-κB activation. In a previous report, we identified the role of glycogen synthase kinase-3β (GSK-3β) in NF-κB activation by regulating IKKγ/NEMO. Here, we show that NEMO phosphorylation by GSK-3β leads to NEMO localization into multivesicular bodies (MVBs). Using the endosome marker Rab5, we observed localization into endosomes. Using siRNA, we identified the AAA-ATPase Vps4A, which is involved in recycling the ESCRT machinery by facilitating its dissociation from endosomal membranes, which is necessary for NEMO stability and NF-κB activation. Co-immunoprecipitation studies of NEMO and mutated NEMO demonstrated its direct interaction with Vps4A, which requires NEMO phosphorylation. The transfection of cells by a mutated and constitutively active form of Vps4A, Vps4A-E233Q, resulted in the formation of large vacuoles and strong augmentation in NEMO expression compared to GFP-Vps4-WT. In addition, the overexpression of the mutated form of Vps4A led to increased NF-κB activation. The treatment of cells with the pharmacologic V-ATPase inhibitor bafilomycin A led to a dramatic downregulation of NEMO and, in this way, inhibited NF-κB signal transduction. These results reveal an unexpected role for GSK-3β and V-ATPase in NF-κB signaling activation.

Underlying Inborn Errors of Immunity in Patients With Evans Syndrome and Multilineage Cytopenias: A Single-Centre Analysis

Background

Evans syndrome (ES) is a rare disorder classically defined as the simultaneous or sequential presence of autoimmune haemolytic anaemia and immune thrombocytopenia, but it has also been described as the presence of at least two autoimmune cytopenias. Recent reports have shown that ES is often a manifestation of an underlying inborn error of immunity (IEI) that can benefit from specific treatments.

Aims

The aim of this study is to investigate the clinical and immunological characteristics and the underlying genetic background of a single-centre cohort of patients with ES.

Methods

Data were obtained from a retrospective chart review of patients with a diagnosis of ES followed in our centre. Genetic studies were performed with NGS analysis of 315 genes related to both haematological and immunological disorders, in particular IEI.

Results

Between 1985 and 2020, 40 patients (23 men, 17 women) with a median age at onset of 6 years (range 0-16) were studied. ES was concomitant and sequential in 18 (45%) and 22 (55%) patients, respectively. Nine of the 40 (8%) patients had a positive family history of autoimmunity. Other abnormal immunological features and signs of lymphoproliferation were present in 24/40 (60%) and 27/40 (67%) of cases, respectively. Seventeen out of 40 (42%) children fit the ALPS diagnostic criteria. The remaining 21 (42%) and 2 (5%) were classified as having an ALPS-like and an idiopathic disease, respectively. Eighteen patients (45%) were found to have an underlying genetic defect on genes FAS, CASP10, TNFSF13B, LRBA, CTLA4, STAT3, IKBGK, CARD11, ADA2, and LIG4. No significant differences were noted between patients with or without variant and between subjects with classical ES and the ones with other forms of multilineage cytopenias.

Conclusions

This study shows that nearly half of patients with ES have a genetic background being in most cases secondary to IEI, and therefore, a molecular evaluation should be offered to all patients.

NEMO Gene Mutations in Two Chinese Females with Incontinentia Pigmenti

Purpose

To identify the mutations of the NEMO gene in two Chinese females with incontinentia pigmenti.

Patients and Methods

Patients were both from Nanchong, Sichuan Province. Genomic DNA was extracted from the peripheral blood of patients and patient 1ʹs father. The mutations of the NEMO gene in patient 1 by GAP polymerase chain reaction and Sanger sequencing and her father were detected. NEMO-specific polymerase chain reaction and Sanger sequencing were used to identify the NEMO gene mutation in patient 2.

Results

DNA analysis identified a rare frameshift mutation, c.723_c.724insCAGG(p.A242QfsX15) in exon 5 of the NEMO gene in patient 1 with a family history but not in her healthy father. The common deletion of exons 4–10 of the NEMO gene was found in sporadic patient 2.

Conclusion

Our data revealed that the rare frameshift mutation, c.723_c.724insCAGG(p.A242QfsX15) in exon 5 of the NEMO gene in patient 1 and the deletion of exons 4–10 of the NEMO gene in patient 2 could cause the occurrence of IP. Genetic testing is helpful for early diagnosis and genetic counseling for families.

Mechanistic insights into the activation of the IKK kinase complex by the Kaposi's Sarcoma Herpes virus oncoprotein vFLIP

Constitutive activation of the canonical NF-κB signaling pathway is a major factor in Kaposi’s sarcoma-associated herpes virus pathogenesis where it is essential for the survival of primary effusion lymphoma. Central to this process is persistent upregulation of the inhibitor of κB kinase (IKK) complex by the virally encoded oncoprotein vFLIP. Although the physical interaction between vFLIP and the IKK kinase regulatory component essential for persistent activation, IKKγ, has been well characterized, it remains unclear how the kinase subunits are rendered active mechanistically. Using a combination of cell-based assays, biophysical techniques, and structural biology, we demonstrate here that vFLIP alone is sufficient to activate the IKK kinase complex. Furthermore, we identify weakly stabilized, high molecular weight vFLIP–IKKγ assemblies that are key to the activation process. Taken together, our results are the first to reveal that vFLIP-induced NF-κB activation pivots on the formation of structurally specific vFLIP–IKKγ multimers which have an important role in rendering the kinase subunits active through a process of autophosphorylation. This mechanism of NF-κB activation is in contrast to those utilized by endogenous cytokines and cellular FLIP homologues.

Genetically programmed alternative splicing of NEMO mediates an autoinflammatory disease phenotype

Host defense and inflammation are regulated by the NF-κB essential modulator (NEMO), a scaffolding protein with a broad immune cell and tissue expression profile. Hypomorphic mutations in inhibitor of NF-κB kinase regulatory subunit gamma (IKBKG) encoding NEMO typically present with immunodeficiency. Here, we characterized a pediatric autoinflammatory syndrome in 3 unrelated male patients with distinct X-linked IKBKG germline mutations that led to overexpression of a NEMO protein isoform lacking the domain encoded by exon 5 (NEMO-Δex5). This isoform failed to associate with TANK binding kinase 1 (TBK1), and dermal fibroblasts from affected patients activated NF-κB in response to TNF but not TLR3 or RIG-I–like receptor (RLR) stimulation when isoform levels were high. By contrast, T cells, monocytes, and macrophages that expressed NEMO-Δex5 exhibited increased NF-κB activation and IFN production, and blood cells from these patients expressed a strong IFN and NF-κB transcriptional signature. Immune cells and TNF-stimulated dermal fibroblasts upregulated the inducible IKK protein (IKKi) that was stabilized by NEMO-Δex5, promoting type I IFN induction and antiviral responses. These data revealed how IKBKG mutations that lead to alternative splicing of skipping exon 5 cause a clinical phenotype we have named NEMO deleted exon 5 autoinflammatory syndrome (NDAS), distinct from the immune deficiency syndrome resulting from loss-of-function IKBKG mutations.

Characterization of a small-molecule inhibitor targeting NEMO/IKKβ to suppress colorectal cancer growth

NEMO/IKKβ complex is a central regulator of NF-κB signaling pathway, its dissociation has been considered to be an attractive therapeutic target. Herein, using a combined strategy of molecular pharmacological phenotyping, proteomics and bioinformatics analysis, Shikonin (SHK) is identified as a potential inhibitor of the IKKβ/NEMO complex. It destabilizes IKKβ/NEMO complex with IC50 of 174 nM, thereby significantly impairing the proliferation of colorectal cancer cells by suppressing the NF-κB pathway in vitro and in vivo. In addition, we also elucidated the potential target sites of SHK in the NEMO/IKKβ complex. Our study provides some new insights for the development of potent small-molecule PPI inhibitors.

Human Genetic Diseases Linked to the Absence of NEMO: An Obligatory Somatic Mosaic Disorder in Male

De novo somatic mutations are well documented in diseases such as neoplasia but are rarely reported in rare diseases. Hovewer, severe genetic diseases that are not compatible with embryonic development are caused exclusively by deleterious mutations that could only be found as mosaic and not as inherited mutations. We will review here the paradigmatic case of Incontinentia Pigmenti, a rare X-linked dominant disease caused by deficiency of the NEMO (also called IKKgamma) protein, which plays a pivotal role in tissue homeostasis. The loss-of-function mutations of NEMO are embryonically lethal in males while females survive because of unbalanced X-inactivation due to NEMO wild type (WT) expressing cells survival despite of NEMO mutant expressing cells. The few surviving IP males are obligatory mosaic mutants with the typical clinical presentation of IP in female. Indeed, the IP pathogenesis in the female and most likely also in the male somatic mosaics is based on the cellular effects of an impaired NEMO activity, but in the context of the interaction of genetically different cells in the affected tissue, which might underline the inflammatory status.

Phänotypisches und genetisches Spektrum von Incontinentia pigmenti – eine große Fallserie

HINTERGRUND

Incontinentia pigmenti ist eine seltene X-chromosomal dominant vererbte Systemerkrankung, die vor allem die Haut, aber auch andere neuroektodermale Gewebe wie Zähne, Haare, Augen und das zentrale Nervensystem betrifft.

PATIENTEN UND METHODIK

Diese multizentrische Fallserienstudie wurde an drei europäischen Hautkliniken durchgeführt und umfasste 30 Patienten mit Incontinentia pigmenti. Zwanzig Patienten wurden klinisch und genetisch untersucht, weitere zehn nur genetisch.

ERGEBNISSE

Die Studie umfasste 28 Frauen und zwei Männer mit einem medianen Alter von drei Jahren. Kutane Manifestationen zeigten sich bei allen 20 Patienten mit klinischen Daten. Stadium I wurde in 90 % dieser Patienten beobachtet. Stadium IV wurde bereits im Alter von einem Jahr beobachtet. Zahn- (81 %), Haar- (78 %) und neurologische Anomalien (53 %) waren häufiger als in bisherigen Berichten. Vierzehn Hautbiopsien zeigten typische Merkmale des entsprechenden Stadiums. Genetische Tests wurden bei 24 Patienten durchgeführt, von denen 14 die häufige Exon 4-10-Deletion und sieben andere pathogene Varianten aufwiesen, darunter drei unveröffentlichte Mutationen. In drei weiteren Fällen wurden keine genetischen Veränderungen gefunden.

SCHLUSSFOLGERUNGEN

In dieser Studie reichte der Phänotyp von lediglich subtil ausgeprägter Hautbeteiligung bis hin zu schweren Multisystemerkrankungen. Die extrakutane Beteiligung sollte zum Zeitpunkt der Diagnose und in regelmäßigen Abständen evaluiert werden, da sich einige Manifestationen erst mit der Zeit entwickeln.

SUMMARY

Background and objectives Incontinentia pigmenti is a rare X-linked dominantly inherited systemic disease affecting primarily the skin but also other neuroectodermal tissues such as teeth, hair, eyes, and the central nervous system. Patients and methods This multicenter case series study was conducted at three European departments of Dermatology including 30 patients with incontinentia pigmenti. Twenty patients were evaluated clinically and genetically, another ten only genetically. Results The study included 28 females and two males with a median age of three years. Cutaneous manifestations were present in all 20 patients with clinical data. Stage I was observed in 90 % of those patients. Stage IV was observed as early as one year of age. Dental (81 %), hair (78 %) and neurological anomalies (53 %) were more frequent than previously reported. Fourteen skin biopsies showed typical features of the corresponding stage. Genetic testing of 24 patients revealed the common exon 4-10 deletion in 14 cases and seven other pathogenic variants, including three unpublished mutations. In another three cases, no genetic alterations were found. Conclusions In this study, the phenotype ranged from only subtle cutaneous involvement to severe multisystemic disorders. Extracutaneous involvement should be evaluated at the time of diagnosis and in regular intervals, as some manifestations may develop over time.

Low Density Granulocytes and Dysregulated Neutrophils Driving Autoinflammatory Manifestations in NEMO Deficiency

NF-κB essential modulator (NEMO, IKK-γ) deficiency is a rare combined immunodeficiency caused by mutations in the IKBKG gene. Conventionally, patients are afflicted with life threatening recurrent microbial infections. Paradoxically, the spectrum of clinical manifestations includes severe inflammatory disorders. The mechanisms leading to autoinflammation in NEMO deficiency are currently unknown. Herein, we sought to investigate the underlying mechanisms of clinical autoinflammatory manifestations in a 12-years old male NEMO deficiency (EDA-ID, OMIM #300,291) patient by comparing the immune profile of the patient before and after hematopoietic stem cell transplantation (HSCT). Response to NF-kB activators were measured by cytokine ELISA. Neutrophil and low-density granulocyte (LDG) populations were analyzed by flow cytometry. Peripheral blood mononuclear cells (PBMC) transcriptome before and after HSCT and transcriptome of sorted normal-density neutrophils and LDGs were determined using the NanoString nCounter gene expression panels. ISG15 expression and protein ISGylation was based on Immunoblotting. Consistent with the immune deficiency, PBMCs of the patient were unresponsive to toll-like and T cell receptor-activators. Paradoxically, LDGs comprised 35% of patient PBMCs and elevated expression of genes such as MMP9, LTF, and LCN2 in the granulocytic lineage, high levels of IP-10 in the patient's plasma, spontaneous ISG15 expression and protein ISGylation indicative of a spontaneous type I interferon (IFN) signature were observed, all of which normalized after HSCT. Collectively, our results suggest that type I IFN signature observed in the patient, dysregulated LDGs and spontaneously activated neutrophils, potentially contribute to tissue damage in NEMO deficiency.

Inborn Errors of Immunity With Fetal or Perinatal Clinical Manifestations

In this article we revised the literature on Inborn Errors of Immunity (IEI) keeping our focus on those diseases presenting with intrauterine or perinatal clinical manifestations. We opted to describe our findings according to the IEI categories established by the International Union of Immunological Societies, predominantly addressing the immunological features of each condition or group of diseases. The main finding is that such precocious manifestations are largely concentrated in the group of primary immune regulatory disorders (PIRDs) and not in the group of classical immunodeficiencies. The IEI categories with higher number of immunological manifestations in utero or in perinatal period are: (i) diseases of immune dysregulation (HLH, IPEX and other Tregopathies, autosomal recessive ALPS with complete lack of FAS protein expression) and (ii) autoinflammatory diseases (NOMID/CINCA, DIRA and some interferonopathies, such as Aicardi-Goutières syndrome, AGS, and USP18 deficiency). Regarding the other IEI categories, some patients with Omenn syndrome (an atypical form of SCID), and a few X-linked CGD patients present with clinical manifestations at birth associated to immune dysregulation. The most frequent clinical features were hydrops fetalis, intrauterine growth retardation leading to fetal loss, stillbirths, and prematurity, as in HLH and IPEX. Additionally, pseudo-TORCH syndrome was observed in AGS and in USP18 deficiency. The main goal of our review was to contribute to increasing the medical awareness of IEI with intrauterine and perinatal onset, which has obvious implications for diagnosis, treatment, and genetic counseling.

Phenotypic and genetic spectrum of incontinentia pigmenti - a large case series

BACKGROUND AND OBJECTIVES

Incontinentia pigmenti is a rare X-linked dominantly inherited systemic disease affecting primarily the skin but also other neuroectodermal tissues such as teeth, hair, eyes, and the central nervous system.

PATIENTS AND METHODS

This multicenter case series study was conducted at three European departments of Dermatology including 30 patients with incontinentia pigmenti. Twenty patients were evaluated clinically and genetically, another ten only genetically.

RESULTS

The study included 28 females and two males with a median age of three years. Cutaneous manifestations were present in all 20 patients with clinical data. Stage I was observed in 90 % of those patients. Stage IV was observed as early as one year of age. Dental (81 %), hair (78 %) and neurological anomalies (53 %) were more frequent than previously reported. Fourteen skin biopsies showed typical features of the corresponding stage. Genetic testing of 24 patients revealed the common exon 4-10 deletion in 14 cases and seven other pathogenic variants, including three unpublished mutations. In another three cases, no genetic alterations were found.

CONCLUSIONS

In this study, the phenotype ranged from only subtle cutaneous involvement to severe multisystemic disorders. Extracutaneous involvement should be evaluated at the time of diagnosis and in regular intervals, as some manifestations may develop over time.

Ectodysplasin pathogenic variants affecting the furin-cleavage site and unusual clinical features define X-linked hypohidrotic ectodermal dysplasia in India

Hypohidrotic ectodermal dysplasia (HED) is a rare genetic disorder caused by mutational inactivation of a developmental pathway responsible for generation of tissues of ectodermal origin. The X-linked form accounts for the majority of HED cases and is caused by Ectodysplasin (EDA) pathogenic variants. We performed a combined analysis of 29 X-linked hypohidrotic ectodermal dysplasia (XLHED) families (including 12 from our previous studies). In addition to the classical triad of symptoms including loss (or reduction) of ectodermal structures, such as hair, teeth, and sweat glands, we detected additional HED-related clinical features including facial dysmorphism and hyperpigmentation in several patients. Interestingly, global developmental delay was identified as an unusual clinical symptom in many patients. More importantly, we identified 22 causal pathogenic variants that included 15 missense, four small in-dels, and one nonsense, splice site, and large deletion each. Interestingly, we detected 12 unique (India-specific) pathogenic variants. Of the 29 XLHED families analyzed, 11 (38%) harbored pathogenic variant localized to the furin cleavage site. A comparison with HGMD revealed significant differences in the frequency of missense pathogenic variants; involvement of specific exons and/or protein domains and transition/transversion ratios. A significantly higher proportion of missense pathogenic variants (33%) localized to the EDA furin cleavage when compared to HGMD (7%), of which p.R155C, p.R156C, and p.R156H were detected in three families each. Therefore, the first comprehensive analysis of XLHED from India has revealed several unique features including unusual clinical symptoms and high frequency of furin cleavage site pathogenic variants.

Severe COVID-19 and long COVID in a 31-year-old woman with incontinentia pigmenti: A case report

Incontinentia pigmenti is a rare genetic disease affecting the skin, microvasculature, and central nervous system, in which a hyperactive inflammatory response is observed. Due to the inflammatory phase of COVID-19 and associated cytokine storm, infection with SARS-CoV-2 in individuals with incontinentia pigmenti is a concern. Furthermore, type I interferon autoantibodies are found in life-threatening COVID-19 pneumonia and in 25% of individuals with incontinentia pigmenti. The present case report describes a 31-year-old Caucasian woman with incontinentia pigmenti and severe COVID-19. She was hospitalized for oxygen therapy, intravenous antibiotics, and corticosteroids. Eight months later, she is still symptomatic. To our knowledge, she is the first reported case of long COVID in incontinentia pigmenti. Increased autoimmunity may be implicated in both incontinentia pigmenti and long COVID. Pending evidence-based guidelines, COVID-protective measures including vaccination should be recommended to all patients with incontinentia pigmenti. Specific interferon therapy may be considered along with usual COVID treatment.

An infant with X-linked anhidrotic ectodermal dysplasia with immunodeficiency presenting with Pneumocystis pneumonia: A case report

Pneumocystis jirovecii pneumonia associated with primary immunodeficiency should be considered in infants with slowly progressing cyanosis, even without fever or respiratory symptoms. Genetic counseling is crucial for incontinentia pigmenti families in advance of pregnancy because lethal infections can occur before the diagnosis of X-linked anhidrotic ectodermal dysplasia with immunodeficiency.

Genetic screening of children with marrow failure. The role of primary Immunodeficiencies

The differential diagnosis of marrow failure (MF) is crucial in the diagnostic work-up, since genetic forms require specific care. We retrospectively studied all patients with single/multi-lineage MF evaluated in a single-center to identify the type and incidence of underlying molecular defects. The diepoxybutane test was used to screen Fanconi Anemia. Other congenital MFs have been searched using Sanger and/or Next Generation Sequencing analysis, depending on the available tools over the years. Between 2009-2019, 97 patients (aged 0-32 years-median 5) with single-lineage (29%) or multilineage (68%) MF were evaluated. Fifty-three (54%) and 28 (29%) were diagnosed with acquired and congenital MF, respectively. The remaining 16 (17%), with trilinear (n=9) and monolinear (n=7) MF, were found to have an underlying primary immunodeficiency (PID) and showed clinical and biochemical signs of immune-dysregulation in 10/16 (62%) and in 14/16 (87%) of cases, respectively. Clinical signs were also found in 22/53 (41%) and 8/28 (28%) patients with idiopathic and classical cMF, respectively. Eight out of 16 PIDs patients were successfully transplanted, four received immunosuppression, two did not require treatment, and the remaining two died. We show that patients with single/multi-lineage MF may have underlying PIDs in a considerable number of cases and that MF may represent a relevant clinical sign in patients with PIDs, thus widening their clinical phenotype. An accurate immunological work-up should be performed in all patients with MF, and PID-related genes should be considered when screening MF in order to identify disorders that may receive targeted treatments and/or appropriate conditioning regimens before transplant.

Exome sequencing enables diagnosis of X-linked hypohidrotic ectodermal dysplasia in patient with eosinophilic esophagitis and severe atopy

X-linked hypohidrotic ectodermal dysplasia (XLHED) is the most common form of ectodermal dysplasia. Clinical and genetic heterogeneity between different ectodermal dysplasia types and evidence of incomplete penetrance and variable expressivity increase the potential for misdiagnosis. We describe a family with X-linked hypohidrotic ectodermal dysplasia (XLHED) presenting with variable expressivity of symptoms between affected siblings. In addition to the classical signs of hypohidrosis, hypotrichosis and hypodontia, the index patient—a 5 year old boy, also presented with a severe atopy phenotype that was not observed in the other two affected brothers. Exome sequencing in the index and the mother identified a pathogenic nonsense variant in EDA (NM_001399.4: c.766 C>T; p. Gln256Ter). This study highlights how exome sequencing was crucial in establishing a precise molecular diagnosis of XLHED by enabling us to rule out other differential diagnoses including NEMO deficiency syndrome, that was initially presented as a clinical diagnosis to the family.

Combined immunodeficiency caused by a novel homozygous NFKB1 mutation

BACKGROUND

Genetic faults in several components of the nuclear factor-κB pathway cause immunodeficiency. Most defects lead to combined immunodeficiency with a range of severity. Heterozygous mutations in NFKB1 were associated with common variable immunodeficiency, however, homozygous mutations have not been described.

OBJECTIVE

We studied the molecular basis of combined immunodeficiency in a patient who presented with failure to thrive, persistent EBV viremia and hepatitis, pneumocystis jirovecii pneumonitis, and generalized lymphadenopathy.

METHODS

Whole genome and exome sequencing followed by Sanger confirmation were performed to identify the genetic defect. Molecular and cellular techniques were used to assess the variant impact on the nuclear factor-κB pathway and lymphocyte function.

RESULTS

Genetic analysis revealed a novel homozygous mutation in NFKB1, c.2878G>A, p.Gly960Arg (G960R). This affected p105 phosphorylation and p50 formation on antigen and cytokine stimulation, as well as attenuating nuclear signal transmission. As a result, both T- and B-cell maturation and function were perturbed. The number of memory CD4⁺ T cells were reduced, while CD8⁺ T cells consisted predominately of expanded differentiated populations. The function of T cells were diminished as shown by reduced responses to mitogens as well as diminished cytokine secretion. B-cell maturation was also affected, with decreased IgD⁺CD27⁺ memory B cells while transitional B cells were increased, likely contributing to the reduced ability to produce specific antibodies.

CONCLUSION

Homozygous G960R mutation in NFKB1 leads to a severe clinical presentation of combined immunodeficiency. This was associated with blockade of nuclear factor-κB pathway signaling, resulting in aberrations in T- and B-cell maturation and function.

Negative regulation of NEMO signaling by the ubiquitin E3 ligase MARCH2

NF‐κB essential modulator (NEMO) is a key regulatory protein that functions during NF‐κB‐ and interferon‐mediated signaling in response to extracellular stimuli and pathogen infections. Tight regulation of NEMO is essential for host innate immune responses and for maintenance of homeostasis. Here, we report that the E3 ligase MARCH2 is a novel negative regulator of NEMO‐mediated signaling upon bacterial or viral infection. MARCH2 interacted directly with NEMO during the late phase of infection and catalyzed K‐48‐linked ubiquitination of Lys326 on NEMO, which resulted in its degradation. Deletion of MARCH2 resulted in marked resistance to bacterial/viral infection, along with increased innate immune responses both in vitro and in vivo. In addition, MARCH2^−/− mice were more susceptible to LPS challenge due to massive production of cytokines. Taken together, these findings provide new insight into the molecular regulation of NEMO and suggest an important role for MARCH2 in homeostatic control of innate immune responses.

Structurally plastic NEMO and oligomerization prone IKK2 subunits define the behavior of human IKK2:NEMO complexes in solution

The human IκB Kinase (IKK) is a multisubunit protein complex of two kinases and one scaffolding subunit that controls induction of transcription factor NF-κB activity. IKK behaves as an entity of aberrantly high apparent molecular weight in solution. Recent X-ray crystallographic and cryo-electron microscopy structures of individual catalytic subunits (IKK1/IKKα and IKK2/IKKβ) reveal that they are both stably folded dimeric proteins that engage in extensive homo-oligomerization through unique surfaces that are required for activation of their respective catalytic activities. The NEMO/IKKγ subunit is a predominantly coiled coil protein that is required for activation of IKK through the canonical NF-κB signaling pathway. Here we report size-exclusion chromatography, multi-angle light scattering, analytical centrifugation, and thermal denaturation analyses of full-length human recombinant NEMO as well as deletion and disease-linked variants. We observe that NEMO is predominantly a dimer in solution, although by virtue of its modular coiled coil regions NEMO exhibits complicated solution dynamics involving portions that are mutually antagonistic toward homodimerization. This behavior causes NEMO to behave as a significantly larger sized particle in solution. Analyses of NEMO in complex with IKK2 indicate that NEMO preserves this structurally dynamic character within the multisubuit complex and provides the complex-bound IKK2 further propensity toward homo-oligomerization. These observations provide critical information on the structural plasticity of NEMO subunit dimers which helps clarify its role in diseases and in IKK regulation through oligomerization-dependent phosphorylation of catalytic IKK2 subunit dimers.

Regulation of B-cell function by NF-kappaB c-Rel in health and disease

B cells mediate humoral immune response and contribute to the regulation of cellular immune response. Members of the Nuclear Factor kappaB (NF-κB) family of transcription factors play a major role in regulating B-cell functions. NF-κB subunit c-Rel is predominantly expressed in lymphocytes, and in B cells, it is required for survival, proliferation, and antibody production. Dysregulation of c-Rel expression and activation alters B-cell homeostasis and is associated with B-cell lymphomas and autoimmune pathologies. Based on its essential roles, c-Rel may serve as a potential prognostic and therapeutic target. This review summarizes the current understanding of the multifaceted role of c-Rel in B cells and B-cell diseases.

Successful Allogeneic Stem Cell Transplantation in Nuclear Factor-Kappa B Essential Modulator Deficiency Syndrome After Treosulfan-Based Conditioning: A Case Report

BACKGROUND

X-linked EDA-ID1 (ectodermal dysplasia, anhidrotic, with immunodeficiency 1, Online Mendelian Inheritance in Man [OMIM] 300291), or NEMO (nuclear factor kappa B essential modulator) deficiency syndrome, is caused by mutations in the IKBKG/NEMO gene. We report the case of a boy with EDA-ID1 who underwent allogeneic stem cell transplantation.

METHODS

In early infancy, the patient developed an atypical, severe, initial manifestation resembling Omenn syndrome with infections, and he underwent allogeneic stem cell transplantation from an unrelated 9 of 10 HLA matched donor with a mismatch in the DQB1 allele after conditioning with treosulfan, fludarabine, thiotepa, and antithymocyte globulin (Grafalon). The post-transplant period was complicated by cytomegalovirus replication and mild, grade 2 graft vs host disease. Because of NEMO deficiency syndrome-associated enteropathy and continuous weight loss, parenteral nutrition was started and the patient was fed an elemental formula and a gluten-free diet. Over a period of 3 years, the patient had 7 incidents of blood stream infections caused by Staphylococci or gut-derived Gram-negative flora, with 1 incident of septic shock caused by Escherichia coli. The blood stream infection stopped after gastrointestinal tract decontamination was done once per month for 7-day courses alternately with rifaximin, vancomycin, and gentamicin sulfate.

CONCLUSIONS

Patients with NEMO deficiency syndrome require very complex, multidisciplinary care, and immunodeficiency correction can only be observed as one of the critical points in patient care. Developmental problems, enteropathy with the need for intravenous hyperalimentation, and specific interventions for other clinical manifestations of multifaceted syndrome are needed for proper care.

Phenotypical T Cell Differentiation Analysis: A Diagnostic and Predictive Tool in the Study of Primary Immunodeficiencies

Multiparametric flow cytometry (MFC) represents a rapid, highly reproducible, and sensitive diagnostic technology for primary immunodeficiencies (PIDs), which are characterized by a wide range of T cell perturbations and a broad clinical and genetic heterogeneity. MFC data from CD4+ and CD8+ T cell subsets were examined in 100 patients referred for Primary Immunodeficiencies to our center. Naïve, central memory, effector memory, and terminal effector memory cell differentiation stages were defined by the combined expression CD45RA/CD27 for CD4 and CD45RA/CCR7 for CD8. Principal component analysis (PCA), a non-hypothesis driven statistical analysis, was applied to analyze MFC data in order to distinguish the diverse PIDs. Among severe lymphopenic patients, those affected by severe combined and combined immunodeficiency (SCID and CID) segregated in a specific area, reflecting a homogenous, and a more severe T cell impairment, compared to other lymphopenic PID, such as thymectomized and partial DiGeorge syndrome patients. PID patients with predominantly antibody defects were distributed in a heterogeneous pattern, but unexpectedly PCA was able to cluster some patients' resembling CID, hence warning for additional and more extensive diagnostic tests and a diverse clinical management. In conclusion, PCA applied to T cell MFC data might help the physician to estimate the severity of specific PID and to diversify the clinical and diagnostic approach of the patients.

Expanding the Clinical and Genetic Spectra of Primary Immunodeficiency-Related Disorders With Clinical Exome Sequencing: Expected and Unexpected Findings

Primary immunodeficiencies (PIDs) refer to a clinically, immunologically, and genetically heterogeneous group of over 350 disorders affecting development or function of the immune system. The increasing use of next-generation sequencing (NGS) technology has greatly facilitated identification of genetic defects in PID patients in daily clinical practice. Several NGS approaches are available, from the unbiased whole exome sequencing (WES) to specific gene panels. Here, we report on a 3-year experience with clinical exome sequencing (CES) for genetic diagnosis of PIDs. We used the TruSight One sequencing panel, which includes 4,813 disease-associated genes, in 61 unrelated patients (pediatric and adults). The analysis was done in 2 steps: first, we focused on a virtual PID panel and then, we expanded the analysis to the remaining genes. A molecular diagnosis was achieved in 19 (31%) patients: 12 (20%) with mutations in genes included in the virtual PID panel and 7 (11%) with mutations in other genes. These latter cases provided interesting and somewhat unexpected findings that expand the clinical and genetic spectra of PID-related disorders, and are useful to consider in the differential diagnosis. We also discuss 5 patients (8%) with incomplete genotypes or variants of uncertain significance. Finally, we address the limitations of CES exemplified by 7 patients (11%) with negative results on CES who were later diagnosed by other approaches (more specific PID panels, WES, and comparative genomic hybridization array). In summary, the genetic diagnosis rate using CES was 31% (including a description of 12 novel mutations), which rose to 42% after including diagnoses achieved by later use of other techniques. The description of patients with mutations in genes not included in the PID classification illustrates the heterogeneity and complexity of PID-related disorders.

Ripoptocide - A Spark for Inflammation

The clinical success of biologics that inhibit TNF (Tumor Necrosis Factor) in inflammatory bowel diseases (IBD), psoriasis and rheumatoid arthritis (RA) has clearly established a pathogenic role for this cytokine in these inflammatory disorders. TNF binding to its receptors activates NFκB and MAPK signaling, inducing the expression of downstream pro-inflammatory genes. This is thought to be the primary mechanism by which TNF elicits inflammation. TNF is also a well-known trigger of caspase-dependent apoptosis or caspase-independent necroptosis. Whether cell death has any role in TNF-mediated inflammation has been less clear. Emerging data from animal models now suggest that cellular demise caused by TNF may indeed provoke inflammation. The default response of most cells to TNF stimulation is survival, rather than death, due to the presence of two sequential cell death checkpoints. The early checkpoint is transcription-independent involving the non-degradative ubiquitination of RIPK1 to prevent RIPK1 from becoming a death-signaling molecule. The later checkpoint requires the induction of pro-survival genes by NFκB-mediated transcription. When the early checkpoint is disrupted, RIPK1 initiates cell death and we suggest the term ripoptocide to describe this manner of death (encompassing both apoptosis and necroptosis). The sensitivity of a cell to ripoptocide is determined by the balance between regulatory molecules that enforce and those that disassemble the early checkpoint. As there is evidence suggesting that ripoptocide is inflammatory, individuals may develop inflammation due to ripoptocide brought about by genetic, epigenetic or post-translational alteration of these checkpoint regulators. For these individuals, drugs that reinforce the early checkpoint and inhibit ripoptocide could be useful in ameliorating inflammation.

The Incontinentia Pigmenti Genetic Biobank: study design and cohort profile to facilitate research into a rare disease worldwide

Incontinentia pigmenti (IP; OMIM#308300) is a rare genetic disease resulting in neuroectodermal defects, which can lead to disability. At present, there is neither definitive cure available nor are there any sufficiently reliable insights to predict the severity of the disease. We launched the Incontinentia Pigmenti Genetic Biobank (IPGB) project ( http://www.igb.cnr.it/ipgb ) in 2015 to establish a large-scale deposit of biological samples, to provide detailed clinical information about children diagnosed with IP and to facilitate research. We have built a cohort comprising samples of 381 clinically confirmed patients with IP and 633 healthy individuals recruited through IP patients' associations. The collection includes 269 trios, 83 duos, and 95 families with at least two affected members and represents an extensive dataset (200 cooperative medical institutes, 139 in Italy and 61 worldwide) that enables a comprehensive phenotyping. Joining the IPGB guarantees all participants access to the results including the genetic testing of IP and the long-term storage of the samples. The IPGB is the largest IP sample collection and one of the largest rare-disease-oriented collections in the world and will be open to requests for access to data by the national and international scientific community.

Incontinentia pigmenti in adults

Incontinentia Pigmenti (IP; MIM 308300) is an X-linked dominant genodermatosis caused by pathogenic variant in IKBKG. The phenotype in adults is poorly described compared to that in children. Questionnaire survey of 99 affected women showed an age at diagnosis from newborn to 41 years, with 53 diagnosed by 6 months of age and 30 as adults. Stage I, II, and III lesions persisted in 16%, 17%, and 71%, respectively, of those who had ever had them. IP is allelic to two forms of ectodermal dysplasia. Many survey respondents reported hypohidrosis and/or heat intolerance and most had Stage IV findings. This suggests that "Stage IV" may be congenitally dysplastic skin that becomes more noticeable with maturity. Fifty-one had dentures or implants with 26 having more invasive jaw or dental surgery. Half had wiry or uncombable hair. Seventy-three reported abnormal nails with 27 having long-term problems. Cataracts and retinal detachment were the reported causes of vision loss. Four had microphthalmia. Respondents without genetic confirmation of IP volunteered information suggesting more involved phenotype or possibly misassigned diagnosis. Ascertainment bias likely accounts for the low prevalence of neurocognitive problems in the respondents.

NF-κB pathway and the Goldilocks principle: Lessons from human disorders of immunity and inflammation

Nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) signaling pathways play a key role in various cell processes related to host immunity. The last few years have seen an explosion of disorders associated with NF-κB components from core members of the canonical and noncanonical cascades to adaptor protein and ubiquitination-related enzymes. Disease phenotypes have extended beyond susceptibility to infections and include autoimmunity, lymphoproliferation, atopy, and inflammation. Concurrently, studies are unveiling a tightly regulated system marked by extensive cross-talk between the canonical and noncanonical pathways, as well as among the NF-κB and other signaling pathways. As the rate of discovery in the realm of NF-κB defects accelerates, this review presents a timely summary of major known defects causing human disease, as well as diagnostic, therapeutic, and research challenges and opportunities.

Incontinentia Pigmenti

Incontinentia pigmenti (Bloch-Sulzberger syndrome) is a rare neuroectodermal dysplasia. It is an X-linked dominant disorder caused by mutations in the IKBKG/NEMO gene on Xq28. Approximately 80% of patients have a deletion of exons 4 to 10. Incontinentia pigmenti has an estimated incidence of 0.7 cases per 100,000 births. In hemizygous males, it is usually lethal, while in females, it has a wide spectrum of clinical manifestations. Incontinentia pigmenti is a multisystemic disease that invariably features skin changes. These changes are the main diagnostic criteria and they evolve in 4 stages, in association with other abnormalities affecting the central nervous system, eyes, teeth, mammary glands, hair, nails, skin, and other parts of the body. The aim of this brief review is to highlight the clinical features of this genodermatosis and underline the importance of case-by-case interdisciplinary management, including genetic counseling.