Objective Develop response criteria for juvenile dermatomyositis (JDM). Methods We analyzed the performance of 312 definitions that used core set measures (CSM) from either the International Myositis Assessment and Clinical Studies Group (IMACS) or the Pediatric Rheumatology International Trials Organization (PRINTO) and were derived from natural history data and a conjoint-analysis survey. They were further validated in the PRINTO trial of prednisone alone compared to prednisone with methotrexate or cyclosporine and the Rituximab in Myositis trial. Experts considered 14 top-performing candidate criteria based on their performance characteristics and clinical face validity using nominal group technique at a consensus conference. Results Consensus was reached for a conjoint analysis–based continuous model with a Total Improvement Score of 0-100, using absolute percent change in CSM with thresholds for minimal (≥30 points), moderate (≥45), and major improvement (≥70). The same criteria were chosen for adult dermatomyositis/polymyositis with differing thresholds for improvement. The sensitivity and specificity were 89% and 91-98% for minimal, 92-94% and 94-99% for moderate, and 91-98% and 85-85% for major improvement, respectively, in JDM patient cohorts using the IMACS and PRINTO CSM. These criteria were validated in the PRINTO trial for differentiating between treatment arms for minimal and moderate improvement (P=0.009–0.057) and in the Rituximab trial for significantly differentiating the physician rating of improvement (P<0.006). Conclusion The response criteria for JDM was a conjoint analysis–based model using a continuous improvement score based on absolute percent change in CSM, with thresholds for minimal, moderate, and major improvement.

ObjectiveInclusion body myositis (IBM) is characterized by a combination of inflammatory and degenerative changes affecting muscle. While the primary cause of IBM is unknown, genetic factors may influence disease susceptibility. To determine genetic factors contributing to the etiology of IBM, we conducted the largest genetic association study of the disease to date, investigating immune‐related genes using the Immunochip.MethodsA total of 252 Caucasian patients with IBM were recruited from 11 countries through the Myositis Genetics Consortium and compared with 1,008 ethnically matched controls. Classic HLA alleles and amino acids were imputed using SNP2HLA.ResultsThe HLA region was confirmed as the most strongly associated region in IBM (P = 3.58 × 10−33). HLA imputation identified 3 independent associations (with HLA–DRB1*03:01, DRB1*01:01, and DRB1*13:01), although the strongest association was with amino acid positions 26 and 11 of the HLA–DRB1 molecule. No association with anti–cytosolic 5′‐nucleotidase 1A–positive status was found independent of HLA–DRB1*03:01. There was no association of HLA genotypes with age at onset of IBM. Three non‐HLA regions reached suggestive significance, including the chromosome 3 p21.31 region, an established risk locus for autoimmune disease, where a frameshift mutation in CCR5 is thought to be the causal variant.ConclusionThis is the largest, most comprehensive genetic association study to date in IBM. The data confirm that HLA is the most strongly associated region and identifies novel amino acid associations that may explain the risk in this locus. These amino acid associations differentiate IBM from polymyositis and dermatomyositis and may determine properties of the peptide‐binding groove, allowing it to preferentially bind autoantigenic peptides. A novel suggestive association within the chromosome 3 p21.31 region suggests a role for CCR5.

To test the overtraining-related "imbalanced amino acid hypothesis" (19), the influence of an unaccustomed average 103 %.4 wk-1 increase in training mileage (ITV) on performance and on serum levels of individual amino acids (AAs) was examined in distance runners and controlled by an unaccustomed average 152%.4 wk-1 increase in tempo-pace and interval runs (ITI). Two mmol.l-1 lactate performance (2 LP) increased, 4 LP stagnated and total running distance (TD) decreased in the incremental test during ITV--which may indicate an ITV-dependent overtraining--in contrast to an ITI-related increase in 2 LP, 4 LP and TD. The summed serum AAs decreased in ITV (2744 +/- 534 vs 2933 +/- 663 umol.l-1; p < 0.05) in contrast to an ITI-related increase (3541 +/- 657 vs 3252 +/- 885 umol.l-1; p < 0.05) with an average 29% higher final summed AAs concentration during ITI (p < 0.05). During ITV 12 individual AAs decreased by 6-17%, 8 remained constant and 3 increased (Cys, Met, fTrp) by 6-19%, as opposed to an ITI-related increase in 16 AA by 6-55%. The observed ITV-related changes in serum AAs profile were smaller than after completing contests as a marathon, a 100 km-run or an ultra-triathlon. It may be concluded that the observed small changes in AAs profile or AAA/BCAA and AA/LNAA ratios only represent an epiphenomenon without recognizable influence on incremental test performance, since increases in fTrp/LNAA ratios (+28% in ITV vs +45% in ITI) were found to be related both to performance impairment (ITV) and improvement (ITI).

Objective. Somatic mutations in UBA1 have recently been causally linked to a severe adult-onset inflammatory condition referred to as VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. Ubiquitinactivating enzyme E1 (UBA-1) is of fundamental importance to the modulation of ubiquitin homeostasis and to the majority of downstream ubiquitylation-dependent cellular processes. Direct sequencing analysis of exon 3 containing the prevalent variants p.Met41Leu, p.Met41Val, and/or p.Met41Thr is usually used to confirm the disease-associated mutations.Methods. We studied the clinical, biochemical, and molecular genetic characteristics of a 59-year-old man with a 2-year history of arthritis, fever, night sweats, nonspecific skin rash, lymphadenopathy, and myelodysplastic syndrome with multilineage dysplasia.Results. The mutational analysis revealed a previously undescribed sequence variant c.1430G>C in exon 14 (p.Gly477Ala) in the gene UBA1. In vitro enzymatic analyses showed that p.Gly477Ala led to both decreased E1 ubiquitin thioester formation and E2 enzyme charging.Conclusion. We report a case of a patient of European ancestry with clinical manifestations of VEXAS syndrome associated with a newly identified dysfunctional UBA-1 enzyme variant. Due to the patient's insufficient response to various immunosuppressive treatments, allogeneic hematopoietic stem cell transplantation was performed, which resulted in significant improvement of clinical and laboratory manifestations of the disease.