Novel insights into FAS defects underlying autoimmune lymphoproliferative syndrome revealed by studies in consanguineous patients

Genetic Testing in Patients with Autoimmune Lymphoproliferative Syndrome: Experience of 802 Patients at Cincinnati Children's Hospital Medical Center

Autoimmune lymphoproliferative syndrome (ALPS) is a rare genetic disorder featuring chronic lymphadenopathy, splenomegaly, cytopenias, and increased lymphoma risk. Differentiating ALPS from immunodeficiencies with overlapping symptoms is challenging. This study evaluated the performance and the diagnostic yield of a 15-gene NGS panel for ALPS at Cincinnati Children's Hospital Medical Center. Samples from 802 patients submitted for ALPS NGS panel were studied between May 2014 and January 2023. A total of 62 patients (7.7%) had a definite diagnosis: 52/62 cases (84%) showed 37 unique pathogenic/likely pathogenic germline FAS variants supporting ALPS diagnosis (6.5%, 52/802). The ALPS diagnostic yield increased to 30% in patients who additionally fulfilled abnormal ALPS immunology findings criteria. 17/37 (46%) diagnostic FAS variants were novel variants reported for the first time in ALPS. 10/802 cases (1.2%) showed diagnostic findings in five genes (ADA2, CTLA4, KRAS, MAGT1, NRAS) which are related to autoimmune lymphoproliferative immunodeficiency (ALPID). Family studies enabled the reclassification of variants of unknown significance (VUS) and also the identification of at-risk family members of FAS-positive patients, which helped in the follow-up diagnosis and treatment. Alongside family studies, complete clinical phenotypes and abnormal ALPS immunology and Fas-mediated apoptosis results helped clarify uncertain genetic findings. This study describes the largest cohort of genetic testing for suspected ALPS in North America and highlights the effectiveness of the ALPS NGS panel in distinguishing ALPS from non-ALPS immunodeficiencies. More comprehensive assessment from exome or genome sequencing could be considered for undefined ALPS-U patients or non-ALPS immunodeficiencies after weighing cost, completeness, and timeliness of different genetic testing options.

Autoimmune lymphoproliferative syndrome: A disorder of immune dysregulation

Autoimmune Lymphoproliferative Syndrome (ALPS) is an autoimmune disease that has been reported in over 2200 patients. It is a rare, genetic disease where pathogenic variants occur in the extrinsic pathway of apoptosis. Various mutations in different genes, such as FAS, FASL, and CASP10, can result in ALPS. Most commonly, pathogenic variants occur in the FAS receptor. This malfunctioning pathway allows for the abnormal accumulation of lymphocytes, namely CD3 + TCRαβ+CD4 - CD8- (double negative (DN) T) cells, which are a hallmark of the disease. This disease usually presents in childhood with lymphadenopathy and splenomegaly as a result of lymphoproliferation. Over time, these patients may develop cytopenias or lymphomas because of irregularities in the immune system. Current treatments include glucocorticoids, mycophenolate mofetil, sirolimus, immunoglobulin G, and rituximab. These medications serve to manage the symptoms and there are no standardized recommendations for the management of ALPS. The only curative therapy is a bone marrow transplant, but this is rarely done because of the complications. This review serves to broaden the understanding of ALPS by discussing the mechanism of immune dysregulation, how the symptoms manifest, and the mechanisms of treatment. Additionally, we discuss the epidemiology, comorbidities, and medications relating to ALPS patients across the United States using data from Cosmos.

Novel Insights into YB-1 Signaling and Cell Death Decisions

YB-1 belongs to the evolutionarily conserved cold-shock domain protein family of RNA binding proteins. YB-1 is a well-known transcriptional and translational regulator, involved in cell cycle progression, DNA damage repair, RNA splicing, and stress responses. Cell stress occurs in many forms, e.g., radiation, hyperthermia, lipopolysaccharide (LPS) produced by bacteria, and interferons released in response to viral infection. Binding of the latter factors to their receptors induces kinase activation, which results in the phosphorylation of YB-1. These pathways also activate the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a well-known transcription factor. NF-κB is upregulated following cellular stress and orchestrates inflammatory responses, cell proliferation, and differentiation. Inflammation and cancer are known to share common mechanisms, such as the recruitment of infiltrating macrophages and development of an inflammatory microenvironment. Several recent papers elaborate the role of YB-1 in activating NF-κB and signaling cell survival. Depleting YB-1 may tip the balance from survival to enhanced apoptosis. Therefore, strategies that target YB-1 might be a viable therapeutic option to treat inflammatory diseases and improve tumor therapy.

Targeted therapy for intervertebral disc degeneration: inhibiting apoptosis is a promising treatment strategy

Intervertebral disc (IVD) degeneration (IDD) is a multifactorial pathological process associated with low back pain (LBP). The pathogenesis is complicated, and the main pathological changes are IVD cell apoptosis and extracellular matrix (ECM) degradation. Apoptotic cell loss leads to ECM degradation, which plays an essential role in IDD pathogenesis. Apoptosis regulation may be a potential attractive therapeutic strategy for IDD. Previous studies have shown that IVD cell apoptosis is mainly induced by the death receptor pathway, mitochondrial pathway, and endoplasmic reticulum stress (ERS) pathway. This article mainly summarizes the factors that induce IDD and apoptosis, the relationship between the three apoptotic pathways and IDD, and potential therapeutic strategies. Preliminary animal and cell experiments show that targeting apoptotic pathway genes or drug inhibition can effectively inhibit IVD cell apoptosis and slow IDD progression. Targeted apoptotic pathway inhibition may be an effective strategy to alleviate IDD at the gene level. This manuscript provides new insights and ideas for IDD therapy.

Mutations primarily alter the inclusion of alternatively spliced exons

Genetic analyses and systematic mutagenesis have revealed that synonymous, non-synonymous and intronic mutations frequently alter the inclusion levels of alternatively spliced exons, consistent with the concept that altered splicing might be a common mechanism by which mutations cause disease. However, most exons expressed in any cell are highly-included in mature mRNAs. Here, by performing deep mutagenesis of highly-included exons and by analysing the association between genome sequence variation and exon inclusion across the transcriptome, we report that mutations only very rarely alter the inclusion of highly-included exons. This is true for both exonic and intronic mutations as well as for perturbations in trans. Therefore, mutations that affect splicing are not evenly distributed across primary transcripts but are focussed in and around alternatively spliced exons with intermediate inclusion levels. These results provide a resource for prioritising synonymous and other variants as disease-causing mutations.