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Adult Familial Mediterranean Fever (FMF): is a single MEFV mutation sufficient to cause severe disease?

Article title: Clinical characteristics and outcomes of adult FMF patients: comparison between those with one versus two

pathogenic MEFV exon 10 mutations

First author: Anaël Dumont

Journal: Joint Bone Spine

Author of the abstract: Rim BOURGUIBA


FMF adulte : une seule mutation MEFV suffit‑elle à rendre la maladie sévère ?

Introduction

Familial Mediterranean Fever (FMF) is an autoinflammatory disease caused by mutations in MEFV. While two pathogenic mutations typically lead to a classic and more severe phenotype, the clinical expression in patients with only one pathogenic mutation remains debated. This study compared adult FMF patients according to whether they carried one or two pathogenic MEFV mutations.


Methods

A French single‑center retrospective cohort included 581 adult FMF patients: 178 with a single pathogenic mutation and 403 with two pathogenic mutations. Diagnosis used Eurofever/PRINTO criteria, and all patients underwent MEFV sequencing. A focused analysis compared M694V/E148Q versus M694V/WT.


Results

Compared with biallelic patients, heterozygous patients were older at diagnosis and disease onset, had more personal and family history of recurrent aphthous stomatitis, and a higher BMI. No AA amyloidosis was observed in heterozygotes, and they required lower colchicine doses. These differences remained significant after adjustment for age at onset. No clinical difference was found between M694V/E148Q and M694V/WT.


Conclusion

Adult FMF patients with a single pathogenic MEFV mutation show distinct clinical features and outcomes compared with those carrying two mutations. Findings highlight FMF phenotypic heterogeneity and support tailoring management to the patient’s genetic profile.



 
 
 

Diagnosis traps for patients with acquired NLRP3 mutation (CAPS)

First author: M. DELPLANQUE et al,

Journal: European Journal of Internal Medicine

Pièges diagnostiques chez les patients atteints d'une mutation acquise de NLRP3 (CAPS)

Summary:

The article highlights the diagnostic challenges of cryopyrin-associated periodic syndromes CAPS, caused by NLRP3 gene mutations. These autoinflammatory diseases include three main forms: familial cold autoinflammatory syndrome (FCAS), Muckle-Wells syndrome (MWS), and Chronic Infantile Neurological Cutaneous and Articular (CINCA) syndrome.

The study presents two cases of patients with acquired somatic NLRP3 mutations, illustrating the difficulty of diagnosis due to atypical phenotypes:

  • Patient 1 (P1): A 46-year-old woman with neuroinflammatory symptoms (persistent headaches, aseptic meningitis, hearing loss), initially misdiagnosed. A somatic M406I mutation was identified after 10 years of diagnostic wandering, explaining her atypical presentation. Treatment with anti-IL-1 drastically improved her condition.

  • Patient 2 (P2): A male patient with severe CINCA syndrome since infancy, presenting with urticaria, arthritis, and growth delay. His genetic diagnosis was challenging, and the M406V mutation was only detected at the age of 15 using deep sequencing techniques.

The authors emphasize that somatic mutations in the NACHT domain of NLRP3 lead to constitutive activation of the inflammasome, resulting in excessive IL-1β production and severe chronic inflammation. The study underscores the importance of advanced genetic sequencing to detect these mutations, particularly in atypical cases.

Conclusion

Identifying somatic mutations in NLRP3 is crucial to avoid misdiagnosis and ensure effective treatment. Diagnostic delays can be prolonged in the absence of classic clinical signs (such as urticaria), and next-generation sequencing is essential for detecting low-percentage mosaicism.



 
 
 
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