A novel truncating mutation in MYD88 in a patient with BCG adenitis, neutropenia and delayed umbilical cord separation

Inborn Errors of Immunity in Early Childhood: Essential Insights for the Neonatologist

BACKGROUND

Inborn errors of immunity (IEI), formerly referred to as primary immunodeficiencies, manifest with a wide range of symptoms such as increased susceptibility to infections, immune dysregulation, and autoinflammation. Although most cases manifest in childhood, onset during the neonatal period is rare but potentially critical.

SUMMARY

In this review, we discuss the diverse clinical presentations of IEI and the specific challenges they pose to neonatologists. Rather than detailing every molecular defect, we focus on common clinical scenarios in neonates and young infants, providing practical diagnostic strategies to ensure timely and effective therapeutic interventions.

KEY MESSAGES

Clinical presentations of IEI in neonates may include delayed separation of the umbilical cord, skin rashes such as eczema and erythroderma, and recurrent episodes of inflammation. We also highlight immunological emergencies that require urgent medical attention, such as hyperinflammatory activity mimicking acute neonatal liver failure, sometimes seen in hemophagocytic lymphohistiocytosis. We also discuss appropriate medical action in the case of a positive newborn screening for severe T-cell defects. Early medical intervention in such circumstances may significantly improve outcomes.

Successful CNS-Centric Therapeutic Management and Genomic Profiling of Primary Cranial Vault Diffuse Large B-Cell Lymphoma

Primary cranial vault lymphoma (PCVL) is a rare lymphoma involving the skull with or without extra- and intracranial extension. Most cases of PCVL are diffuse large B-cell lymphoma (DLBCL). We report a case of primary cranial vault diffuse large B-cell lymphoma (PCV-DLBCL) that was successfully treated with anthracycline-based chemoimmunotherapy (CIT) alternating with central nervous system (CNS)-directed CIT with high-dose methotrexate and high-dose cytarabine. CNS-centric therapy was given for suspected cerebral cortical involvement and presumed elevated risk of CNS recurrence. The patient has remained in complete remission for 4.25 years following treatment. We suggest that PCV-DLBCL is potentially curable with CNS-directed therapy. Additionally, we provide genomic profiling results indicating an indeterminate cell of origin and multiple genetic mutations which are not frequently seen in DLBCL.

Human variation in population-wide gene expression data predicts gene perturbation phenotype

Population-scale datasets of healthy individuals capture genetic and environmental factors influencing gene expression. The expression variance of a gene of interest (GOI) can be exploited to set up a quasi loss- or gain-of-function "in population" experiment. We describe here an approach, huva (human variation), taking advantage of population-scale multi-layered data to infer gene function and relationships between phenotypes and expression. Within a reference dataset, huva derives two experimental groups with LOW or HIGH expression of the GOI, enabling the subsequent comparison of their transcriptional profile and functional parameters. We demonstrate that this approach robustly identifies the phenotypic relevance of a GOI allowing the stratification of genes according to biological functions, and we generalize this concept to almost 16,000 genes in the human transcriptome. Additionally, we describe how huva predicts monocytes to be the major cell type in the pathophysiology of STAT1 mutations, evidence validated in a clinical cohort.

Defects of the Innate Immune System and Related Immune Deficiencies

The innate immune system is the host's first line of defense against pathogens. Toll-like receptors (TLRs) are pattern recognition receptors that mediate recognition of pathogen-associated molecular patterns. TLRs also activate signaling transduction pathways involved in host defense, inflammation, development, and the production of inflammatory cytokines. Innate immunodeficiencies associated with defective TLR signaling include mutations in NEMO, IKBA, MyD88, and IRAK4. Other innate immune defects have been associated with susceptibility to herpes simplex encephalitis, viral infections, and mycobacterial disease, as well as chronic mucocutaneous candidiasis and epidermodysplasia verruciformis. Phagocytes and natural killer cells are essential members of the innate immune system and defects in number and/or function of these cells can lead to recurrent infections. Complement is another important part of the innate immune system. Complement deficiencies can lead to increased susceptibility to infections, autoimmunity, or impaired immune complex clearance. The innate immune system must work to quickly recognize and eliminate pathogens as well as coordinate an immune response and engage the adaptive immune system. Defects of the innate immune system can lead to failure to quickly identify pathogens and activate the immune response, resulting in susceptibility to severe or recurrent infections.

Disease Presentation, Treatment Options, and Outcomes for Myeloid Immunodeficiencies

PURPOSE OF REVIEW

Up-to-date review on various types of immunodeficiencies with a significant myeloid component including some more recently described congenital disorders.

RECENT FINDINGS

While a number of disorders have been described in the past, genetic sequencing has led to the identification of the specific disorders and clarified their pathophysiology. Advances in genetic therapies including genetic editing should provide future treatments beyond hematopoietic stem cell transplant for patients with these rare disorders. Neutrophils (or granulocytes) are a major contributor to infection surveillance and clearance, and defective neutrophils characteristically lead to pyogenic infections. Deficiency in numbers, either iatrogenic or congenital; functional defects; and/or inability to target to the sites of infection can all lead to serious morbidity and mortality; however, myeloid-based immunodeficiencies are not all the same. Having absent neutrophils, that is, neutropenia, has implications different to those of having dysfunctional neutrophils as will become evident as the various disorders are reviewed.

Multiple Family Members With Delayed Cord Separtion and Combined Immunodeficiency With Novel Mutation in IKBKB

Background: Inhibitor of kappa kinase 2 (IKK2) deficiency is a recently described combined immunodeficiency. It undermines the nuclear factor-kappa B (NF-κB) activation pathway. Methods: The clinical and immunological data of four patients diagnosed with combined immunodeficiency (CID) from two related Saudi families were collected. Autozygosity mapping of all available members and whole exome sequencing of the index case were performed to define the genetic etiology. Results: The patients had early onset (2-4 months of age) severe infections caused by viruses, bacteria, mycobacteria, and fungi. They all had hypogammaglobulinemia and low absolute lymphocyte count. Their lymphocytes failed to respond to PHA mitogen stimulation. A novel homozygous non-sense mutation in the IKBKB gene, c.850C>T (p. Arg284*) was identified in the index patient and segregated with the disease in the rest of the family. He underwent hematopoietic stem cell transplantation (HSCT) from a fully matched sibling with no conditioning. The other three patients succumbed to their disease. Interestingly, all patients had delayed umbilical cord separation. Conclusion: IKK2 deficiency causes CID with high mortality. Immune reconstitution with HSCT should be considered as early as possible. Delayed umbilical cord separation in CID patients may be a clue to IKK2 deficiency.