Familial Mediterranean Fever: unexpected symptoms in some patients

Title in English: Non-canonical manifestations of FMF in homozygous M694V MEFV genotype: Insights from a large patient cohort

First author: Eitan Giat

Journal: Seminars in Arthritis and Rheumatism

Link to PubMed : https://pubmed.ncbi.nlm.nih.gov/40902213/

Summary by: Dr Catherine Grandpeix-Guyodo

Introduction:

Familial Mediterranean Fever (FMF) is the most common monogenic autoinflammatory disease worldwide. Among the MEFV gene mutations associated with a classic FMF phenotype, homozygous M694V variants are classically associated with the most severe forms of the disease, with more frequent attacks, more frequent arthritis, lower limb pain during exercise, poorer quality of life, higher colchicine requirements, poorer treatment response, and increased risk of inflammatory amyloidosis, with half of AA amyloidosis cases in FMF patients being associated with a homozygous M694V genotype. This study examined clinical and biological manifestations other than those already known, associated with homozygous M694V mutations in a large cohort of patients in Israel.

Patients and methods:

This was a retrospective study of adults with FMF followed between 2010 and 2020 at an Israeli hospital center. Patients carrying the homozygous M694V mutation were compared to a control group of patients with a classic FMF phenotype and either homozygous MEFV mutations other than M694V, compound heterozygotes, or heterozygotes (known variants associated with classic FMF but also presence of variants of unknown significance (VUS) such as E148Q, K695R, P369S).

Results:

The cohort included 3,866 FMF patients, 47.6% male, and 517 (13.4%) homozygous M694V. Significant differences between the two groups were, in homozygous M694V: higher colchicine dosage (median 2 mg/day versus 1.5 mg/day) despite better compliance, greater number of colchicine failures requiring addition of biotherapy (anti-IL1 or anti-TNF) (30% versus 4.2%), higher number of associated pathologies (*ankylosing spondylitis (AS), Behçet's disease, congestive heart failure, deep vein thromboses, chronic renal failure, and hepatic dysfunctions*), more significant abnormalities in biological parameters (CRP, ESR, liver enzymes, bilirubin, creatinine, and uric acid), higher number of hospitalizations and emergency room visits, particularly due to FMF attacks.

The results are the same if patients with at least one M694V mutation are excluded from the control group. Moreover, comparison of a heterozygous M694V group to other controls shows no difference.

It should also be noted that homozygous M694V patients on biotherapies had more AS, Behçet's disease, chronic renal failure, hepatic cytolysis, hyperuricemia, emergency room visits, and hospitalizations. However, there was no difference in terms of cardiovascular pathologies between homozygotes on biotherapies and those on colchicine alone.

Discussion:

In addition to what is described in the literature (more severe phenotype, more attacks, specific locations of FMF flares, poorer response to colchicine, more associations with inflammatory diseases, more AA amyloidosis and chronic renal failure), this study shows in FMF patients with homozygous M694V mutation the use of higher colchicine dosages, more frequent use of biotherapies, no increase in ischemic cardiovascular pathologies despite greater inflammation (possibly due to the action of anti-IL1). The study did find a higher rate of congestive heart failure which could be attributed to greater systemic inflammation, as has been shown in rheumatoid arthritis, Crohn's disease, and ulcerative colitis. The same applies to the higher frequency of deep vein thromboses.

Hepatic dysfunctions and hepatic cytolysis were more frequent in homozygous M694V FMF patients and could also be attributed to systemic inflammation that would generate hepatic steatosis.

To better understand the pathophysiological mechanisms, more studies seem necessary.

Conclusion:

In addition to the more severe and complicated presentations of classic FMF associated with the homozygous M694V genotype of MEFV, higher colchicine requirements or even recourse to biotherapies are observed, more frequent associated pathologies such as inflammatory diseases (AS, Behçet), increased frequency of congestive heart failure, deep vein thromboses, chronic renal failure, and liver diseases. Increased biannual monitoring of homozygous M694V patients seems essential.

CAPS: Improving Our Understanding of a Rare Inflammatory Disease Caused by a Partial NLRP3 Gene Mutation

Summary by: Dr Yixiang Yves-Jean Zhu

First author: Bonet N.

Journal: Journal of Clinical Immunology

Reference: J Clin Immunol. 2025 Sep 30;45(1):134. doi: 10.1007/s10875-025-01922-x

Link to PubMed: https://pubmed.ncbi.nlm.nih.gov/41026232/

Introduction:

Cryopyrin-associated periodic syndrome (CAPS) is a rare monogenic autoinflammatory disease associated with gain‑of‑function variants in the NLRP3 gene. These variants lead to constitutive activation of the corresponding inflammasome and excessive production of IL‑1β. The classic manifestations combine a urticaria‑like rash, arthralgia, recurrent fever, neurologic involvement, and sensorineural hearing loss, in a context of biological inflammation (elevated CRP). Within the clinical spectrum of CAPS, Neonatal Onset Multisystem Inflammatory Disease (NOMID) stands out because of its particular severity. Current treatment relies on IL‑1β‑blocking agents, and specific *NLRP3* inflammasome inhibitors such as MCC950 are under investigation. Transmission is usually autosomal dominant, but some cases result from post‑zygotic mutations leading to mosaicism, a phenomenon that remains poorly documented. This retrospective Spanish study reports the largest cohort to date of CAPS patients with NLRP3 mosaicism, providing clinical, genetic, and functional analyses of 17 patients.

Main results:

-Clinical characteristics: Seventeen individuals (7 men, 10 women) were included. Four had a NOMID phenotype, 14 had a CAPS phenotype other than NOMID, and one individual was asymptomatic. The mean age at onset was 26 years (range 0.1–76 years), with two patient subgroups: an early‑onset group (< 5 years) including 6 patients, and a late‑onset group (> 45 years) including 6 patients. The most frequent manifestations were a urticaria‑like rash (100%), arthralgia (87%), recurrent fever (75%), arthritis (68%), and headache (56%).

- Response to treatment: All symptomatic patients received an IL‑1 inhibitor: anakinra (14 patients) or canakinumab (2 patients). A complete response with CRP normalization and clinical improvement was observed in 94% of patients. One case with partial response to anakinra was successfully controlled after switching to canakinumab.

- Genetic and functional data: Sixteen different NLRP3 variants were identified, all located in exon 4, with allele frequencies ranging from 1.3% to 34.8%. In vitro studies confirmed hyperactivation of the inflammasome, which was sensitive to the specific NLRP3 inhibitor MCC950, except for the D303H variant, which was partially resistant.

- Clonal evolution: Longitudinal follow‑up showed stable allele frequency in 54% of cases, an increase in 23% (mainly in patients older than 50 years, suggesting possible clonal hematopoiesis carrying the pathogenic NLRP3 variant, and a decrease in 23%, which may reflect “fatigue” of the mutant clone.

- Distribution of mosaicism: In 64% of patients, mosaicism involved at least myeloid and lymphoid cells, while 36% had mosaicism restricted to myeloid cells. No major clinical differences were observed between these mosaic patterns.

Practical message:

This largest‑to‑date study of mosaic CAPS shows that:

- The clinical picture and treatment response are comparable to those of germline CAPS, and functional studies reveal a similar activation profile.

- Mosaicism may remain stable or fluctuate over time, and the usefulness of monitoring allele frequency for follow‑up remains to be determined.

- Mosaicism may be restricted to myeloid cells, suggesting a later‑acquired variant, without apparent impact on clinical features.

A diagnosis of CAPS should not be ruled out in patients with a compatible phenotype solely on the basis of negative family history. Screening for NLRP3 mosaicism is essential in any adult with a suggestive CAPS presentation, as these patients also show an excellent response to IL‑1 inhibitors. Because mosaicism is more sensitively detected by high‑throughput sequencing, this technique should be preferred when CAPS is suspected, with sufficient read depth to identify low‑frequency allele mosaicism.

Living with Familial Mediterranean Fever (FMF): what helps you cope better?

Article title: The effects of self-efficacy in managing the disease and disease adaptation levels of Familial Mediterranean

Fever (fmf) patients on satisfaction with life: a web-based cross-sectional study

First author: Demir RN

Journal: Orphanet Journal of Rare Diseases

Link to the article: https://ojrd.biomedcentral.com/articles/10.1186/s13023-025-03931-w

Author of the abstract: Rim BOURGUIBA

Abstract

Familial Mediterranean Fever (FMF) is the most common monogenic autoinflammatory disease in the world. It is characterized by recurrent inflammatory episodes of fever, abdominal pain, chest pain, and joint pain. Treatment is based on colchicine as first-line therapy, with biotherapy sometimes necessary. In addition to medical management, patients' ability to adapt to chronic disease and their sense of self-efficacy, defined as their feeling of personal effectiveness in managing the disease, can influence their quality of life. The objective of this study was to evaluate the impact of self-efficacy in FMF management and levels of adaptation to the disease on the satisfaction/quality of life of patients with FMF.

Methods:

A cross-sectional observational study was conducted using an online questionnaire distributed on Facebook and Instagram (FMF patient groups) between February and April 2024. The authors included adult Turkish patients (≥18 years old) who had been diagnosed at least one year prior.

The assessment tools used were:

- Self-Efficacy Scale for Chronic Disease (6 items).

- Adaptation to Chronic Illness Scale (25 items: physical, psychological, and social adaptation).

- Satisfaction With Life Scale.

Results

In this study of 423 adult Turkish patients with FMF, there was a predominance of females (73.8%), with ages ranging from 32 to 45 years. A disease duration of 21 years or more was reported in 38.3% of patients. The average self-efficacy score in disease management was relatively high (4.67/10). Adaptation to the disease was moderate overall (3.10/5), with better physical adaptation (3.36), followed by psychological adaptation (2.92) and social adaptation (2.87). Life satisfaction was below average (2.68/5). The correlation study revealed positive and significant associations between self-efficacy and adaptation (r = 0.532), between self-efficacy and life satisfaction (r = 0.417), and between adaptation and life satisfaction (r = 0.564) (Table 1). Regression analysis showed that self-efficacy explained 17.4% of the variance in life satisfaction, while adaptation to the disease explained 31.8%, confirming their decisive role in the self-management of FMF on quality of life (Table 2).

Conclusion

This study shows that in patients with FMF, self-efficacy and adaptation to the disease directly influence the overall low quality of life in this population. Strengthening therapeutic education and psychosocial support appears essential to improving the quality of life of adult patients with FMF.

Table 1: Correlation study between self-efficacy and quality of life in FMF patients

Table 2: Regression analysis of self-efficacy on quality of life and disease management

Vivre avec la fièvre méditerranéenne familiale : qu’est-ce qui aide à mieux s’en sortir.pd

Download PD • 1.19MB