BACKGROUND. Undifferentiated systemic autoinflammatory diseases (USAIDs) present diagnostic and therapeutic challenges. Chronic interferon (IFN) signaling and cytokine dysregulation may identify diseases with available targeted treatments. METHODS. Sixty-six consecutively referred USAID patients underwent underwent screening for the presence of an interferon signature using a standardized type-I IFN-response-gene score (IRG-S), cytokine profiling, and genetic evaluation by next-generation sequencing. RESULTS. Thirty-six USAID patients (55%) had elevated IRG-S. Neutrophilic panniculitis (40% vs. 0%), basal ganglia calcifications (46% vs. 0%), interstitial lung disease (47% vs. 5%), and myositis (60% vs. 10%) were more prevalent in patients with elevated IRG-S. Moderate IRG-S elevation and highly elevated serum IL-18 distinguished 8 patients with pulmonary alveolar proteinosis (PAP) and recurrent macrophage activation syndrome (MAS). Among patients with panniculitis and progressive cytopenias, 2 patients were compound heterozygous for potentially novel LRBA mutations, 4 patients harbored potentially novel splice variants in IKBKG (which encodes NF-κB essential modulator [NEMO]), and 6 patients had de novo frameshift mutations in SAMD9L. Of additional 12 patients with elevated IRG-S and CANDLE-, SAVI- or Aicardi-Goutières syndrome–like (AGS-like) phenotypes, 5 patients carried mutations in either SAMHD1, TREX1, PSMB8, or PSMG2. Two patients had anti-MDA5 autoantibody–positive juvenile dermatomyositis, and 7 could not be classified. Patients with LRBA, IKBKG, and SAMD9L mutations showed a pattern of IRG elevation that suggests prominent NF-κB activation different from the canonical interferonopathies CANDLE, SAVI, and AGS. CONCLUSIONS. In patients with elevated IRG-S, we identified characteristic clinical features and 3 additional autoinflammatory diseases: IL-18–mediated PAP and recurrent MAS (IL-18PAP-MAS), NEMO deleted exon 5–autoinflammatory syndrome (NEMO-NDAS), and SAMD9L-associated autoinflammatory disease (SAMD9L-SAAD). The IRG-S expands the diagnostic armamentarium in evaluating USAIDs and points to different pathways regulating IRG expression. TRIAL REGISTRATION. ClinicalTrials.gov NCT02974595. FUNDING. The Intramural Research Program of the NIH, NIAID, NIAMS, and the Clinical Center.

Previously, we described associations between health-related quality of life (HRQOL) and disease-related factors among childhood onset systemic lupus erythematosus (cSLE) patients. Here we determined the relationship between HRQOL, disease activity and damage in a large prospective international cohort of cSLE. We compared HRQOL, disease activity and disease damage across different continents and examined the relationship between children's and parents' assessments of HRQOL. Patients with cSLE and their parents completed HRQOL measures at enrollment and ≥4 follow-up visits. Physicians assessed disease activity and damage. The multinational cohort (n = 467) had relatively low disease activity and damage. Patient and parent HRQOL scores were significantly correlated. Asian and European patients had the highest HRQOL, while South and North American patients had lower HRQOL scores. Renal, CNS, skin and musculoskeletal systems exhibited the highest levels of damage. North and South American and Asian patients were more likely to have disease damage and activity scores above median values, compared with Europeans. Asians were more likely to use cyclophosphamide/rituximab. Female gender, high disease activity and damage, non-White ethnicity, and use of cyclophosphamide and/rituximab were related to lower HRQOL. HRQOL domain scores continue to emphasize that SLE has widespread impact on all aspects of children's and parents' lives.

Objective: Fibromyalgia (FM) is defined by idiopathic, chronic, widespread musculoskeletal pain. In adults with FM, a metaanalysis of lower-leg skin biopsy demonstrated 45% pooled prevalence of abnormally low epidermal neurite density (END). END < 5th centile of the normal distribution is the consensus diagnostic threshold for small-fiber neuropathy. However, the clinical significance of END findings in FM is unknown. Here, we examine the prevalence of small-fiber pathology in juvenile FM, which has not been studied previously.Methods: We screened 21 patients aged 13–20 years with FM diagnosed by pediatric rheumatologists. Fifteen meeting the American College of Rheumatology criteria (modified for juvenile FM) underwent lower-leg measurements of END and completed validated questionnaires assessing pain, functional disability, and dysautonomia symptoms. The primary outcome was proportion of FM patients with END < 5th centile of age/sex/race-based laboratory norms. Cases were systematically matched by ethnicity, race, sex, and age to a group of previously biopsied healthy adolescents with selection blinded to biopsy results. All 23 controls matching demographic criteria were included.Results: Among biopsied juvenile FM patients, 53% (8/15) had END < 5th centile vs 4% (1/23) of healthy controls (P < 0.001). Mean patient END was 273/mm² skin surface (95% CI 198–389) vs 413/mm² (95% CI 359–467, P < 0.001). As expected, patients with FM reported more functional disability, dysautonomia, and pain than healthy controls.Conclusion: Abnormal END reduction is common in adolescents with FM, with similar prevalence in adults with FM. More studies are needed to fully characterize the significance of low END in FM and to elucidate the clinical implications of these findings.

Rheumatic diseases in children are associated with significant morbidity andpoor health-related quality of life (HRQOL). There is no health-relatedquality of life (HRQOL) scale available specifically for children with lesscommon rheumatic diseases. These diseases share several features withsystemic lupus erythematosus (SLE) such as their chronic episodic nature,multi-systemic involvement, and the need for immunosuppressive medications.HRQOL scale developed for pediatric SLE will likely be applicable tochildren with systemic inflammatory diseases. We adapted Simple Measure of Impact of Lupus Erythematosus in Youngsters(SMILEY©) to Simple Measure of Impact of Illness in Youngsters(SMILY©-Illness) and had it reviewed by pediatric rheumatologists forits appropriateness and cultural suitability. We tested SMILY©-Illnessin patients with inflammatory rheumatic diseases and then translated it into28 languages. Nineteen children (79% female, n=15) and 17 parents participated. The meanage was 12±4 years, with median disease duration of 21 months (1-172months). We translated SMILY©-Illness into the following 28 languages:Danish, Dutch, French (France), English (UK), German (Germany), German(Austria), German (Switzerland), Hebrew, Italian, Portuguese (Brazil),Slovene, Spanish (USA and Puerto Rico), Spanish (Spain), Spanish(Argentina), Spanish (Mexico), Spanish (Venezuela), Turkish, Afrikaans,Arabic (Saudi Arabia), Arabic (Egypt), Czech, Greek, Hindi, Hungarian,Japanese, Romanian, Serbian and Xhosa. SMILY©-Illness is a brief, easy to administer and score HRQOL scale forchildren with systemic rheumatic diseases. It is suitable for use acrossdifferent age groups and literacy levels. SMILY©-Illness with itsavailable translations may be used as useful adjuncts to clinical practiceand research.

Significance: Pulmonary involvement in childhood-onset systemic lupus erythematosus (cSLE), contributes to significant morbidity and mortality. Manifestations include chronic interstitial pneumonitis, pneumonia, pleuritis, alveolar hemorrhage, and shrinking lung syndrome. However, many patients can be asymptomatic from a respiratory standpoint and still have pulmonary function test (PFT) abnormalities. Our aim is to describe PFT abnormalities in patients with cSLE. Methods: We completed a retrospective review of 42 patients with cSLE followed at our center. These patients were at least 6 years old (so they could complete PFTs). We collected data from July 2015 to July 2020. Results: Out of the 42 patients, 10 (23.8%) had abnormal PFTs. These 10 patients had a mean age at diagnosis of 13 ± 2.9 years. Nine were female. One-fifth (20%) self-identified as Hispanic, 20% as Asian, 10% as Black or African American, and the remaining 50% as “Other.” Of the 10, 3 had restrictive disease only, 3 with diffusion impairment only, and 4 with both restrictive lung disease and diffusion impairment. Patients with restrictive patterns had a mean total lung capacity (TLC) of 72.5 ± 5.8 throughout the study period. The average diffusing capacity for carbon monoxide corrected for hemoglobin (DsbHb) among patients with diffusion limitation during the study period was 64.8 ± 8.3. Conclusions: The most common PFT abnormalities seen in patients with cSLE are alterations in diffusing capacity as well as restrictive lung disease.