Next-generation sequencing reveals genetic heterogeneity in MEFV-negative or heterozygous familial Mediterranean fever: a retrospective study.

BACKGROUND

Familial Mediterranean Fever (FMF) is traditionally linked to MEFV mutations. However, many patients remain genetically unexplained after routine screening. This study evaluates the utility of Next-Generation Sequencing (NGS) in patients with negative or heterozygous MEFV results from fragment analysis.

METHODS

We analyzed 320 patients clinically diagnosed with FMF who had either no mutations or a single heterozygous mutation based on traditional 16-variant screening. NGS was used to sequence the entire MEFV gene and 18 additional autoinflammatory genes.

RESULTS

NGS identified variants (pathogenic, likely pathogenic, or VUS) in 34% of cases. Crucially, NGS detected previously missed MEFV variants (e.g. c.380A > C, c.428 G > T) in 54 patients and identified compound heterozygosity in several others. Furthermore, 45 patients carried variants in non-MEFV genes, including TNFRSF1A, NOD2, and PSTPIP1, suggesting potential oligogenic or modifier effects. Clinical reevaluation of these cases revealed diverse phenotypes, including varying colchicine responses and associations with amyloidosis or neutrophilic dermatoses.

CONCLUSIONS

NGS significantly increases the diagnostic yield in FMF-like presentations by detecting rare MEFV variants and identifying broader genetic heterogeneity. The transition from targeted screening to comprehensive NGS panels provides a deeper understanding of autoinflammatory phenotypes and supports individualized diagnostic and therapeutic strategies in clinical practice.