NOD2 Versus MEFV: Differential Diagnosis of Yao Syndrome and Familial Mediterranean Fever

The expanding clinical spectrum of autoinflammatory diseases with NOD2 variants: a case series and literature review

Objective

To assess the impact conferred by NOD2 variants on the clinical spectrum of patients with systemic autoinflammatory diseases (SAIDs) in Greece.

Methods

Consecutive patients (n=167) with confirmed SAIDs who underwent screening by next generation sequencing (NGS) targeting 26 SAID-associated genes, and carried at least one NOD2 gene variant, were retrospectively studied. The demographic, clinical and laboratory parameters were recorded.

Results

In total, 24 rare NOD2 variants in 23/167 patients (14%) were detected. Notably, 18 patients had at least one co-existing variant in 13 genes other than NOD2. Nine patients had juvenile- and 14 adult-onset disease. All patients presented with symptoms potentially induced by the NOD2 variants. In particular, the candidate clinical diagnosis was Yao syndrome (YAOS) in 12 patients (7% of the whole SAID cohort). The clinical spectrum of patients with YAOS (mean episode duration 8 days) was fever (n=12/12), articular symptoms (n=8), gastrointestinal symptoms (n=7; abdominal pain/bloating in 7; diarrhea in 4; oral ulcers in 3), serositis (n=7), and rash (n=5), while the inflammatory markers were elevated in all but one patient. Most of these patients showed a poor response to nonsteroidal anti-inflammatory drugs (n=7/9), colchicine (n=6/8) and/or anti-TNF treatment (n=3/4), while a complete response was observed in 6/10 patients receiving steroids and 3/5 on anti-IL1 treatment. Another 8 patients were diagnosed with either FMF (n=6) or PFAPA syndrome (n=2) presenting with prominent diarrhea (n=7), oral ulcers (n=2), periorbital swelling and sicca-like symptoms (n=1), or maculopapular rash (n=1). One patient had a clinically undefined SAID, albeit characterized by oral ulcers and diarrhea. Finally, one patient presented with chronic relapsing urticaria with periorbital edema and inflammatory markers, and another one had a Crohn-like syndrome with good response to anti-IL-1 but refractory to anti-TNF treatment.

Conclusion

NOD2 variants were detected in 1 out of 7 SAID patients and seem to have an impact on disease phenotype and treatment response. Further studies should validate combined molecular and clinical data to better understand these distinct nosological entities.

Inflammatory Bowel Disease: Focus on Enteropathic Arthritis and Therapy

Inflammatory bowel disease (IBD) is a chronic inflammatory disease primarily affecting the gastrointestinal (GI) tract and other organs. In this article, we provide a comprehensive review of IBD, particularly in the context of enteropathic arthritis and its therapeutic advances. Patients with IBD present with intestinal and extraintestinal manifestations (EIMs). Enteropathic arthritis or arthritis associated with IBD (Crohn's disease [CD] and ulcerative colitis [UC]) is the most common EIM and can involve both peripheral and axial joints with some overlaps. Furthermore, peripheral arthritis can be divided into two subcategories. Due to its varied inflammatory presentations and association with NOD2 mutations, CD can mimic other autoimmune and autoinflammatory diseases. Differential diagnosis should be extended to include another NOD2-associated disease, Yao syndrome. Therapy for IBD entails a myriad of medications and procedures, including various biologics targeting different pathways and Janus kinase (JAK) inhibitors. A better understanding of the therapeutic efficacy and mechanism of each drug aids in proper selection of more effective treatment for IBD and its associated inflammatory arthritis.