Faculty Bibliography

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a severe inflammatory and hematologic disease caused by somatic mutations in UBA1. Canonical pathogenic mutations at UBA1 p.Met41 (M41) lead to the loss of the cytoplasmic isoform (UBA1b), while non-canonical mutations outside of M41 (non-M41) result in reduced activity of both nuclear and cytoplasmic isoforms. Studies have reported clinical differences between canonical and non-canonical mutations, but these findings are constrained by small sample sizes and scarcity of genetic studies. In our study, we screened 29,000 individuals for UBA1 variants, referred for a broad range of hematologic diseases, and subjected to 62-gene panel sequencing, identifying 232 patients carrying likely disease-causing mutations. We identified decreased polyubiquitylation in all of the 18 UBA1 variants tested and found differences in H2A/B monoubiquitylation alteration between M41 and non-M41 mutations. Our findings confirm that patients harboring M41 mutations present at most with myelodysplastic neoplasms (MDS) and suggest that M41 mutations generally do not tolerate multiple co-mutations. In contrast, non-M41 mutations are more likely to appear with co-mutations and are detected in patients with hematologic neoplasms other than MDS. Our study establishes that M41 and non-M41 mutations exhibit distinct clinical and biological phenotypes, significantly enhancing UBA1 variant interpretation.

Infections are increasingly recognised as a major cause of morbidity and mortality in patients with vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome. We conducted a systematic review to characterise the infectious burden of VEXAS syndrome and propose preventive strategies. We included 57 studies (813 patients) showing that infections in patients with VEXAS syndrome were frequent, severe in 40-60% of cases, and fatal in 6-15% of cases. Pulmonary infections were most common, followed by cutaneous infections and bacteraemia. Opportunistic pathogens, such as Pneumocystis jirovecii, Legionella pneumophila, non-tuberculous mycobacteria, and varicella zoster virus, were frequently reported, even in patients not receiving immunosuppressive therapy, which suggests intrinsic immune dysfunction. Prophylaxis with co-trimoxazole (or other Pneumocystis prophylaxis, such as atovaquone or pentamidine) and valaciclovir should particularly be considered for patients at high risk of infection, including those receiving immunosuppressive therapy and those with lymphopenia, pMet41Val mutation, or previous severe or recurrent infections. Posaconazole might be appropriate in patients with neutropenia who are taking azacitidine. Vaccination against Streptococcus pneumoniae, varicella zoster virus, influenza, and SARS-CoV-2 is recommended. These data highlight the need to integrate infectious risk into VEXAS syndrome management and to evaluate preventive strategies in prospective studies.

OBJECTIVE:Vacuoles E1 enzyme X-linked autoinflammatory somatic syndrome (VEXAS) is a recently identified rare genetic disorder associated with somatic mutations in the UBA1 gene. VEXAS presents with a combination of inflammatory and hematologic manifestations, leading to increased morbidity and mortality. METHODS:Given the variability in disease presentation and the limited number of studies to date, no clinical documents currently exist to provide guidance to health care providers about the management of VEXAS. To address this gap, we formed an international multidisciplinary panel of VEXAS experts. RESULTS:Through formalized meetings and a voting process, the group developed consensus clinical guidance considerations for the management of VEXAS. These considerations offer practical advice on several key topics: (1) clinical features of VEXAS, (2) UBA1 screening methods, (3) the diagnosis of myelodysplastic syndromes (MDSs) in patients with VEXAS, and (4) prognosis and management. The aim is to provide expert guidance on which patients to test, how to test for VEXAS, how to approach MDS in the context of VEXAS, and considerations for management. CONCLUSION/CONCLUSIONS:This work marks the first formal international consensus guidance for VEXAS and is intended to be used as a resource for clinicians seeking to understand the disease and its management.

COPA syndrome, an autosomal-dominant inborn error of immunity, is nonpenetrant in ∼20% of individuals, with no known mediators of protection. Recent studies implicate STING in the pathogenesis of COPA syndrome. We show that the common HAQ STING allele mediates complete clinical protection. We sequenced 35 individuals with COPA mutations, 26 affected patients and 9 unaffected carriers, finding HAQ STING co-segregation with clinical nonpenetrance. Exome sequencing identified only the mutations comprising HAQ STING as variants shared by unaffected carriers and absent in patients. Experimentally, we found that HAQ STING acts dominantly to dampen COPA-dependent STING signaling. Expressing HAQ STING in patient cells rescued the molecular phenotype of COPA syndrome. Our study is the first report of a common and well-tolerated allele mediating complete clinical protection from a severe genetic disorder. Our findings redefine the diagnostic criteria for COPA syndrome, expose functional differences among STING alleles with broad scientific and clinical implications, and reveal a potential universal gene therapy approach for patients.

Somatic mutations (also known as acquired mutations) are emerging as common, age-related processes that occur in all cells throughout the body. Somatic mutations are canonically linked to malignant processes but over the past decade have been increasingly causally connected to benign diseases including rheumatic conditions. Here we outline the contribution of somatic mutations to complex and monogenic immunological diseases with a detailed review of unique aspects associated with such causes. Somatic mutations can cause early- or late-onset rheumatic monogenic diseases but also contribute to the pathogenesis of complex inflammatory and immune-mediated diseases, affect disease progression and define new clinical subtypes. Although even variants with a low variant allele fraction can be pathogenic, clonal dynamics could lead to changes over time in the proportion of mutant cells, with possible phenotypic consequences for the individual. Thus, somatic mutagenesis and clonal expansion have relevant implications in genetic testing and counselling. On the basis of both increased recognition of somatic diseases in clinical practice and improved technical and bioinformatic processes, we hypothesize that there will be an ever-expanding list of somatic mutations in various genes leading to inflammatory conditions, particularly in late-onset disease.

Idiopathic osteoporosis (IOP) is a rare form of early-onset osteoporosis diagnosed in patients with no known metabolic or hormonal cause of bone loss and unknown pathogenesis. Patients with IOP commonly report both childhood fractures and family history of osteoporosis, raising the possibility of genetic etiologies of IOP. Whole-exome sequencing analyses of different IOP cohorts identified multiple variants in melatonin receptor 1A (MTNR1A) with a potential pathogenic outcome. A rare MTNR1A variant (rs374152717) was found in members of an Ashkenazi Jewish family with IOP, and an MTNR1A variant (rs28383653) was found in a nonrelated female IOP cohort (4%). Both variants occur at a substantially higher frequency in Ashkenazi Jewish individuals than in the general population. We investigated consequences of the heterozygous (rs374152717) variant [MTNR1Ac.184+1G>T (MTNR1A