Pre-T cell receptor-α immunodeficiency detected exclusively using whole genome sequencing.

Maturation of αβ lineage T cells in the thymus relies on the formation and cell surface expression of a pre-T cell receptor (TCR) complex, composed of TCRβ chain and pre-TCRα (pTCRα) chain heterodimers, giving rise to a diverse T cell repertoire. Genetic aberrations in key molecules involved in T cell development lead to profound T cell immunodeficiency. Definitive genetic diagnosis guides treatment choices and counseling.

A Unique Comprehensive Model to Screen Newborns for Severe Combined Immunodeficiency-An Ontario Single-Centre Experience Spanning 2013-2023.

Background: Severe combined immunodeficiency (SCID) is a life-threatening genetic disorder caused by critical defects of the immune system. Almost all cases are lethal if not treated within the first two years of life. Early diagnosis and intervention are thus essential for improving patient outcomes.

Utilization of next-generation sequencing to define the role of heterozygous variants in immunodeficiency.

Background: Forkhead box protein N1 (FOXN1) transcription factor plays an essential role in the development of thymic epithelial cells, required for T-cell differentiation, maturation, and function. Biallelic pathogenic variants in cause severe combined immunodeficiency (SCID). More recently, heterozygous variants in identified by restricted gene panels, were also implicated with causing a less severe and variable immunodeficiency.

Autoantibodies against type I IFNs in humans with alternative NF-κB pathway deficiency.

Patients with autoimmune polyendocrinopathy syndrome type 1 (APS-1) caused by autosomal recessive AIRE deficiency produce autoantibodies that neutralize type I interferons (IFNs), conferring a predisposition to life-threatening COVID-19 pneumonia. Here we report that patients with autosomal recessive NIK or RELB deficiency, or a specific type of autosomal-dominant NF-κB2 deficiency, also have neutralizing autoantibodies against type I IFNs and are at higher risk of getting life-threatening COVID-19 pneumonia. In patients with autosomal-dominant NF-κB2 deficiency, these autoantibodies are found only in individuals who are heterozygous for variants associated with both transcription (p52 activity) loss of function (LOF) due to impaired p100 processing to generate p52, and regulatory (IκBδ activity) gain of function (GOF) due to the accumulation of unprocessed p100, therefore increasing the inhibitory activity of IκBδ (hereafter, p52/IκBδ).

RelB-deficient autoinflammatory pathology presents as interferonopathy, but in mice is interferon-independent.

Background: Autoimmune diseases are leading causes of ill health and morbidity and have diverse etiology. Two signaling pathways are key drivers of autoimmune pathology, interferon and nuclear factor-κB (NF-κB)/RelA, defining the 2 broad labels of interferonopathies and relopathies. Prior work has established that genetic loss of function of the NF-κB subunit RelB leads to autoimmune and inflammatory pathology in mice and humans.

The human Stat1 gain-of-function T385M mutation causes expansion of activated T-follicular helper/T-helper 1-like CD4 T cells and sex-biased autoimmunity in specific pathogen-free mice.

Introduction: Humans with gain-of-function (GOF) mutations in STAT1 (Signal Transducer and Activator of Transcription 1), a potent immune regulator, experience frequent infections. About one-third, especially those with DNA-binding domain (DBD) mutations such as T385M, also develop autoimmunity, sometimes accompanied by increases in T-helper 1 (Th1) and T-follicular helper (Tfh) CD4 effector T cells, resembling those that differentiate following infection-induced STAT1 signaling. However, environmental and molecular mechanisms contributing to autoimmunity in STAT1 GOF patients are not defined.

Deep phenotypic characterization of the retinal dystrophy in patients with RNU4ATAC-associated Roifman syndrome.

Purpose: To characterize the retinal phenotype in RNU4ATAC-associated Roifman syndrome.

Methods: Ten patients (including 8 males) with molecularly confirmed Roifman syndrome underwent detailed ophthalmologic evaluation including fundus imaging, fundus autofluorescence (FAF) imaging, spectral-domain optical coherence tomography (SD-OCT), and electroretinography (ERG). Six patients had follow-up eye exams.

NFκB pathway dysregulation due to reduced RelB expression leads to severe autoimmune disorders and declining immunity.

Background: Genetic aberrations in the NFκB pathway lead to primary immunodeficiencies with various degrees of severity. We previously demonstrated that complete ablation of the RelB transcription factor, a key component of the alternative pathway, results in an early manifested combined immunodeficiency requiring stem cell transplantation.

Objective: To study the molecular basis of a progressive severe autoimmunity and immunodeficiency in three patients.

Case Report: Eosinophilic Esophagitis in a Patient With a Novel STAT1 Gain-of-Function Pathogenic Variant.

Background: STAT1 gain-of-function (GOF) is a primary immune dysregulatory disorder marked by wide infectious predisposition (most notably chronic mucocutaneous Candidiasis), autoimmunity, vascular disease and malignant predisposition. While atopic features have been described in some STAT1 GOF patients, they are not considered a predominant feature of the disease. Additionally, while eosinophilic gastrointestinal infiltration has been reported in some cases, this has always been described in the context of pre-existing oropharyngeal and/or esophageal Candidiasis.

Homozygous duplication identified by whole genome sequencing causes LRBA deficiency.

In more than one-third of primary immunodeficiency (PID) patients, extensive genetic analysis including whole-exome sequencing (WES) fails to identify the genetic defect. Whole-genome sequencing (WGS) is able to detect variants missed by other genomics platforms, enabling the molecular diagnosis of otherwise unresolved cases. Here, we report two siblings, offspring of consanguineous parents, who experienced similar severe events encompassing early onset of colitis, lymphoproliferation, and hypogammaglobulinemia, typical of lipopolysaccharide-responsive and beige-like anchor (LRBA) or cytotoxic T lymphocyte antigen 4 (CTLA4) deficiencies.

Thymic Epithelial Cell Alterations and Defective Thymopoiesis Lead to Central and Peripheral Tolerance Perturbation in MHCII Deficiency.

Major Histocompatibility Complex (MHC) class II (MHCII) deficiency (MHCII-D), also known as Bare Lymphocyte Syndrome (BLS), is a rare combined immunodeficiency due to mutations in genes regulating expression of MHCII molecules. MHCII deficiency results in impaired cellular and humoral immune responses, leading to severe infections and autoimmunity. Abnormal cross-talk with developing T cells due to the absence of MHCII expression likely leads to defects in thymic epithelial cells (TEC).

STAT1 gain-of-function heterozygous cell models reveal diverse interferon-signature gene transcriptional responses.

Signal transducer and activator of transcription 1 (STAT1) gain-of-function (GOF) is an autosomal dominant immune disorder marked by wide infectious predisposition, autoimmunity, vascular disease, and malignancy. Its molecular hallmark, elevated phospho-STAT1 (pSTAT1) following interferon (IFN) stimulation, is seen consistently in all patients and may not fully account for the broad phenotypic spectrum associated with this disorder. While over 100 mutations have been implicated in STAT1 GOF, genotype-phenotype correlation remains limited, and current overexpression models may be of limited use in gene expression studies.

Disruption of exon-bridging interactions between the minor and major spliceosomes results in alternative splicing around minor introns.

Vertebrate genomes contain major (>99.5%) and minor (<0.5%) introns that are spliced by the major and minor spliceosomes, respectively.

Ataxia Telangiectasia Diagnosed on Newborn Screening-Case Cohort of 5 Years' Experience.

Ataxia telangiectasia (AT) is a genetic condition caused by mutations involving (Ataxia Telangiectasia Mutated). This gene is responsible for the expression of a DNA double stranded break repair kinase, the ATM protein kinase. The syndrome encompasses combined immunodeficiency and various degrees of neurological abnormalities and increased risk of malignancy.

New insights into minor splicing-a transcriptomic analysis of cells derived from TALS patients.

Minor intron splicing plays a central role in human embryonic development and survival. Indeed, biallelic mutations in , transcribed into the minor spliceosomal U4atac snRNA, are responsible for three rare autosomal recessive multimalformation disorders named Taybi-Linder (TALS/MOPD1), Roifman (RFMN), and Lowry-Wood (LWS) syndromes, which associate numerous overlapping signs of varying severity. Although RNA-seq experiments have been conducted on a few RFMN patient cells, none have been performed in TALS, and more generally no in-depth transcriptomic analysis of the ∼700 human genes containing a minor (U12-type) intron had been published as yet.

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.