Ombrello, Amanda K.

RELA-related disease is a rare, autosomal-dominant condition presenting with immune dysregulation and immunodeficiency. RELA encodes the p65 subunit, a component of the canonical NFκB pathway. The underlying pathogenesis, at least in part, involves impaired NFκB activation, increased susceptibility to TNFα-induced apoptosis, and hyperinflammation. To date, only a modest number of cases have been documented worldwide, and the full clinical and functional spectrum of disease remains incompletely defined. This study represents a large global cohort identified with RELA variants, comprising 40 patients from 30 institutions, expanding our previous report of a single large kindred (1). The clinical spectrum includes arthritis, mucocutaneous ulcers, uveitis, dermatitis, irritable bowel disease, recurrent infections, lymphopenia, hypogammaglobulinemia, recurrent fevers, and susceptibility to neoplasia. The patients represent 36 kindreds with 28 unique RELA variants, of which 15 are missense, 7 nonsense, and 6 frameshift variants. Fifteen are in the Rel homology domain, 7 in the transcriptional activation domain, and 6 in the C-terminal region proximal to TAD (Fig. 1). Functional studies assessed the canonical NFκB pathway in 27% of the cohort (n = 11; healthy controls = 40). Patient peripheral blood mononuclear cells (PBMCs) were used to quantify total and phosphorylated p65 (ph-p65, Ser529) by flow cytometry after stimulation with PMA (100 ng/ml) and ionomycin (1 uM). In 8 patients, we assessed the kinetics of IκBα degradation, required for p65 phosphorylation and nuclear translocation of p65/p50. All patients tested had decreased total p65, while 64% had decreased ph-p65 with altered phosphorylation kinetics. Nearly 45% had impaired IκBα degradation. One patient (P4) demonstrated increased IκBα degradation and ph-p65, while a related proband (P1) had decreased ph-p65. Additionally, P4 did not have the same mucocutaneous clinical phenotype as P1 despite sharing the same RELA variant. This could reflect the effect of other genetic modifiers, epigenetic, environmental, or stochastic variations, which could lead to variable expressivity and/or incomplete penetrance. All patients appeared to have haploinsufficiency, as none had normal levels of p65. This study expands the clinical and genetic spectrum of RELA-related disease and provides mechanistic insights into the impact of these variants on p65 phosphorylation and downstream function, resulting in variable expressivity. Figure 1. RelA protein structure. Represents unique variant locations and categories, key domains, and phosphorylation sites. Source: UniProt. Adapted from (2). BioRender.

Abstract VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome, caused by somatic mutations in UBA1, is an autoinflammatory disorder with diverse systemic manifestations. Thrombosis is a prominent clinical feature of VEXAS syndrome. The risk factors and frequency of thrombosis in VEXAS syndrome are not well described, due to the disease’s recent discovery and the paucity of large databases. We evaluated 119 patients with VEXAS syndrome for venous and arterial thrombosis and correlated their presence with clinical outcomes and survival. Thrombosis occurred in 49% of patients, mostly venous thromboembolism (VTE; 41%). Almost two-thirds of VTEs were unprovoked, 41% were recurrent, and 20% occurred despite anticoagulation. The cumulative incidence of VTE was 17% at 1 year from symptom onset and 40% by 5 years. Cardiac and pulmonary inflammatory manifestations were associated with time to VTE. M41L was positively associated specifically with pulmonary embolism by univariate (odds ratio [OR]: 4.58, confidence interval [CI] 1.28-16.21, P = .02) and multivariate (OR: 16.94, CI 1.99-144.3, P = .01) logistic regression. The cumulative incidence of arterial thrombosis was 6% at 1 year and 11% at 5 years. The overall survival of the entire patient cohort at median follow-up time of 4.8 years was 88%, and there was no difference in survival between patients with or without thrombosis (P = .8). Patients with VEXAS syndrome are at high risk of VTE; thromboprophylaxis should administered be in high-risk settings unless strongly contraindicated.

VEXAS is caused by somatic mutations in UBA1 (UBA1mut) and characterized by heterogenous systemic auto-inflammation and progressive hematologic manifestations, meeting criteria for myelodysplastic syndrome (MDS) and plasma cell dyscrasias. The landscape of myeloid-related gene mutations leading to typical clonal hematopoiesis (CH) in these patients is unknown. Retrospectively, we screened 80 VEXAS patients for CH in their peripheral blood (PB) and correlated findings with clinical outcomes in 77. UBA1mutwere most common at hotspot p.M41 (median variant allele frequency/VAF = 75%). Typical CH mutations co-occurred with UBA1mut in 60% of patients, mostly in DNMT3A and TET2, and were not associated with inflammatory or hematologic manifestations. In prospective single-cell proteogenomic sequencing (scDNA), UBA1mutwas the dominant clone, present mostly in branched clonal trajectories. Based on integrated bulk and scDNA analyses, clonality in VEXAS followed two major patterns: with either typical CH preceding UBA1mutselection in a clone (Pattern 1), or occurring as an UBA1mutsubclone or in independent clones (Pattern 2). VAF in PB differed markedly between DNMT3A and TET2 clones (median VAF of 25% vs 1%). DNMT3A and TET2 clones associated with hierarchies representing patterns 1 and 2, respectively. Overall survival for all patients was 60% at 10 years. Transfusion-dependent anemia, moderate thrombocytopenia, and typical CH mutations, each correlated with poor outcome. In VEXAS, UBA1mut cells are the primary cause of systemic inflammation and marrow failure, being a new molecularly defined somatic entity associated with MDS. VEXAS-associated MDS is distinct from classical MDS in its presentation and clinical course.

Abstract Somatic mutations in UBA1 cause vacuoles, E1 ubiquitin-activating enzyme, X-linked, autoinflammatory somatic (VEXAS) syndrome, an adult-onset inflammatory disease with an overlap of hematologic manifestations. VEXAS syndrome is characterized by a high mortality rate and significant clinical heterogeneity. We sought to determine independent predictors of survival in VEXAS and to understand the mechanistic basis for these factors. We analyzed 83 patients with somatic pathogenic variants in UBA1 at p.Met41 (p.Met41Leu/Thr/Val), the start codon for translation of the cytoplasmic isoform of UBA1 (UBA1b). Patients with the p.Met41Val genotype were most likely to have an undifferentiated inflammatory syndrome. Multivariate analysis showed ear chondritis was associated with increased survival, whereas transfusion dependence and the p.Met41Val variant were independently associated with decreased survival. Using in vitro models and patient-derived cells, we demonstrate that p.Met41Val variant supports less UBA1b translation than either p.Met41Leu or p.Met41Thr, providing a molecular rationale for decreased survival. In addition, we show that these 3 canonical VEXAS variants produce more UBA1b than any of the 6 other possible single-nucleotide variants within this codon. Finally, we report a patient, clinically diagnosed with VEXAS syndrome, with 2 novel mutations in UBA1 occurring in cis on the same allele. One mutation (c.121 A>T; p.Met41Leu) caused severely reduced translation of UBA1b in a reporter assay, but coexpression with the second mutation (c.119 G>C; p.Gly40Ala) rescued UBA1b levels to those of canonical mutations. We conclude that regulation of residual UBA1b translation is fundamental to the pathogenesis of VEXAS syndrome and contributes to disease prognosis.

ObjectiveDeficiency of adenosine deaminase 2 (DADA2) is a monogenic form of vasculitis that can resemble polyarteritis nodosa (PAN). This study was undertaken to identify potential disease‐causing sequence variants in ADA2 in patients with idiopathic PAN, granulomatosis with polyangiitis (GPA), or microscopic polyangiitis (MPA).MethodsPatients with idiopathic PAN (n = 118) and patients with GPA or MPA (n = 1,107) were screened for rare nonsynonymous variants in ADA2 using DNA sequencing methods. ADA‐2 enzyme activity was assessed in selected serum samples.ResultsNine of 118 patients with PAN (7.6%) were identified as having rare nonsynonymous variants in ADA2. Four patients (3.4%) were biallelic for pathogenic or likely pathogenic variants, and 5 patients (4.2%) were monoallelic carriers for 3 variants of uncertain significance and 2 likely pathogenic variants. Serum samples from 2 patients with PAN with biallelic variants were available and showed markedly reduced ADA‐2 enzyme activity. ADA‐2 enzyme testing of 86 additional patients revealed 1 individual with strongly reduced ADA‐2 activity without detectable pathogenic variants. Patients with PAN and biallelic variants in ADA2 were younger at diagnosis than patients with 1 or no variant in ADA2, with no other clinical differences noted. None of the patients with GPA or MPA carried biallelic variants in ADA2.ConclusionA subset of patients with idiopathic PAN meet genetic criteria for DADA2. Given that tumor necrosis factor inhibition is efficacious in DADA2 but is not conventional therapy for PAN, these findings suggest that ADA‐2 testing should strongly be considered in patients with hepatitis B virus–negative idiopathic PAN.