AB1036 AN UNSOLVED CASE: IS THIS A CANDLE-LIKE SYNDROME?
Authors: Alessia Pin, Alessandra Tesser, Flavio Faletra, Alberto Tommasini, Serena Pastore, Andrea Taddio
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Chronic Atypical Neutrophilic Dermatosis with Lipodystrophy and Elevated Temperature (CANDLE) syndrome is a complex autoinflammatory disorders arising from inborn defects in immunoproteasome. Several genes can be involved and cases with digenic inheritance have been described. However, many cases remain without the identification of a specific genetic defect. A positive interferon signature is typically found in patients and may serve as a diagnostic clue. <h3>Objectives</h3> To describe clinical and genetic features in a girl with CANDLE and in her relatives with a variety of different rheumatologic complaints. <h3>Methods</h3> We performed Whole Exome Sequencing (WES) on 10 family members. Moreover, we assessed RNA-seq on three sample from the proband, collected during acute phases of disease (samples positive to class I interferon signature (IS)) (1), and her parents. Results of RNA sequencing (RNA-seq) were compared with specimens from healthy controls. Differentially expressed genes (DEGs) were filtered by fold change &gt; 2 and padj &lt; 0.05. DEGs enrichment were performed using different R packages, such as pathfindR. <h3>Results</h3> We describe the case of a 20 years old girl with clinical and biological data supportive of CANDLE syndrome. At the age of 3 years, she started presenting a clinical picture reminiscent of amyopathic dermatomyositis, with skin rash, lipodystrophy, subcutaneous panniculitis nodules, and more recently with chilblains, skin ulcerations, polyarticular arthritis and alopecia. Her pedigree includes several relatives with rheumatic disorders, but none has a clinical picture as complex and severe as our patient. This girl was found to have a strongly positive class I IS in peripheral blood cells. After several unsuccessful therapeutic attempts with antirheumatic drugs and biologics, the girl showed a dramatic clinical response to the JAK inhibitors tofacitinbib. IS resulted positive also in 4 of her relatives, three of whom presented also rheumatologic symptoms. Conversely, one uncle of the girl was affected with rheumatologic symptoms but had negative IS. The pedigree may suggest a complex pattern of inheritance, likely with a major dominant disorder, whose expression can be modulated by multigenic and/or environmental factors. WES failed to detect significant genetic variants in proteasome components. However, RNA-seq revealed a profile of differentially expressed IFN-regulated genes similar to that reported by Anja Brehm et al. in subjects with CANDLE/PRAAS (2). <h3>Conclusion</h3> Our results suggest that our family may present a multigenic form of CANDLE, with a complete clinical picture only in the proband, whilst other relatives may only present partial or incomplete forms of the disease. <h3>References</h3> [1] Rice GI, et al. Assessment of Type I Interferon Signaling in Pediatric Inflammatory Disease. J Clin Immunol. 2017 Feb;37(2):123- 132. doi: 10.1007/s10875-016-0359-1. Epub 2016 Dec 9. [2] Brehm A, et al. Additive loss-of- function proteasome subunit mutations in patients with CANDLE/PRAAS promote type I IFN production. J Clin Invest. 2016 Feb;126(2):795. doi: 10.1172/JCI86020. Epub 2016 Feb 1. <h3>Disclosure of Interests</h3> None declared