Unexpected finding of AA amyloidosis with novel genetic variants in the MEFV gene in patients undergoing kidney biopsy for proteinuria. A case series.

Amyloidosis is a systemic clinical condition characterised by the extracellular deposition of misfolded proteins in various organs, most frequently involving the heart, kidneys, gastrointestinal tract, and bone marrow. Among its types, AA amyloidosis accounts for approximately 15% of cases and is mainly secondary to chronic infectious or inflammatory conditions. The association between Familial Mediterranean Fever (FMF) and AA amyloidosis is well-established, with the MEFV gene's M694V mutation being the most recognised risk factor. However, the role of other genetic variants often remains underestimated. This case series presents a spectrum of AA amyloidosis patients harbouring various MEFV gene variants. By emphasizing the clinical presentations and diagnostic challenges encountered, this report aims to highlight the clinical significance of heterozygous and less common variants that are frequently overlooked in the progression to AA amyloidosis.