Highlights1. What is already known about this topic? SARS-CoV-2 causes asymptomatic or mild infection in about 80% of humans, while an excessive immune response has killed millions. Differential susceptibility and risk factors became a concern early in the pandemic. Several monogenic defects that involve innate viral sensors or affect interferon response pathways, as well as autoantibodies against type 1 interferons, have been identified in 14% of patients with life-threatening COVID-19. The impact of the novel betacoronavirus infection in patients with known inborn errors of immunity is less clear. Case series and reports from different countries have suggested a minor impact or even a potential protective effect of the IEI for some patients.2. What does this article add to our knowledge? We describe findings and outcomes of COVID-19 in 31 pediatric and adult patients with known IEI from Mexico, 84% of whom survived. Pediatric patients had a higher hospitalization rate. Inpatient mortality was 40%, and ICU mortality was 63%. Six patients died of secondary bacterial infection or uncontrolled systemic inflammation, but not from overwhelming viral infection. One patient with an autoinflammatory disorder under treatment with anakinra had a catastrophic clinical course. Eighty percent of patients received IVIG as part of their treatment for acute SARS-CoV-2 infection.3. How does this study impact current management guidelines? We recommend continued and/or high-dose IVIG in patients with known IEI seeking care for COVID-19. Patients with autoinflammatory disorders, especially those with inflammasome dysregulation, should probably take extreme measures to prevent exposure, while doctors taking care of SARS-CoV-2 infected patients with immune deficiencies must do everything they can to prevent secondary bacterial infections. The high survival of patients with COVID-19 in the context of inborn errors of immunity worldwide (over 80%) might be the result of patientphysician awareness and special care.

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Tumor necrosis factor receptor–associated factor 3 (TRAF3) is a central regulator of immunity. TRAF3 is often somatically mutated in B cell malignancies, but its role in human immunity is not defined. Here, in five unrelated families, we describe an immune dysregulation syndrome of recurrent bacterial infections, autoimmunity, systemic inflammation, B cell lymphoproliferation, and hypergammaglobulinemia. Affected individuals each had monoallelic mutations in TRAF3 that reduced TRAF3 expression. Immunophenotyping showed that patients’ B cells were dysregulated, exhibiting increased nuclear factor-κB 2 activation, elevated mitochondrial respiration, and heightened inflammatory responses. Patients had mild CD4 + T cell lymphopenia, with a reduced proportion of naïve T cells but increased regulatory T cells and circulating T follicular helper cells. Guided by this clinical phenotype, targeted analyses demonstrated that common genetic variants, which also reduce TRAF3 expression, are associated with an increased risk of B cell malignancies, systemic lupus erythematosus, higher immunoglobulin levels, and bacterial infections in the wider population. Reduced TRAF3 conveys disease risks by driving B cell hyperactivity via intrinsic activation of multiple intracellular proinflammatory pathways and increased mitochondrial respiration, with a likely contribution from dysregulated T cell help. Thus, we define monogenic TRAF3 haploinsufficiency syndrome and demonstrate how common TRAF3 variants affect a range of human diseases.

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Introduction: Around 20% of all inborn errors of immunity (IEI) are autosomal dominant or monoallelic, either by haploinsufficiency, negative dominance, or gain of function (GOF). GOF phenotypes usually include autoinflammation, autoimmunity, lymphoproliferation, allergies, and some infections. Case series: We describe the cases of two unrelated patients born of HIV-seroconcordant parents. Both patients are HIV-negative but carry de novo GOF missense variants that resulted in inflammatory lymphoproliferative IEI diseases: signal transducer and activator of transcription 3 (STAT3)-GOF and phosphatidylinositol 3-kinase, catalytic delta (PIK3CD)-GOF. Both variants were found through whole-exome sequencing and confirmed by Sanger. An 11-year-old male with recurrent sinopulmonary infections, dysmorphism, growth delay, bronchiectasis, and mild mental retardation, as well as lymphopenia, thrombocytopenia, and high immunoglobulin M. Both his parents were known to be HIV-positive under anti-retroviral treatment. HIV infection was repeatedly ruled out in the patient, whom through whole-exome sequencing was found to have a heterozygous missense variant in exon 24 of PIK3CD, a hotspot transition, and the most reported variant in PIK3CD-GOF patients. A 6-year-old male with autoimmune hemolytic anemia, lymphoproliferation, short stature, and intractable diarrhea. Both his parents were found to be HIV-positive. HIV was repeatedly ruled out in the patient by ELISA and viral load. He was found to have a heterozygous missense/splice variant in exon 22 of STAT3, a hotspot transition, and the most reported variant in STAT3-GOF patients. Discussion: The AID/APOBEC3 A-H family of proteins are cytidine deaminases that induce G>A hypermutation in both the invading viral DNA and the host genome, which results in stop codons inside the endogenized retroviral sequence. Both variants found in our patients are G to A transitions. Retroviral infection might thus have resulted in host genome instability, and our patients’ rare congenital diseases are the unfortunate consequence of somatic hypermutation in one of their parents’ gametes.