Clinicopathological Assessment of Kidney Biopsies in Children with Familial Mediterranean Fever: A Single-Center Experience.

Objectives: Familial Mediterranean fever (FMF) is a monogenic auto-inflammatory disease which might rarely cause glomerulopathy in patients. The aim of this study was to determine the clinical, demographic, and genetic characteristics and type of glomerular lesions in pediatric FMF patients who underwent kidney biopsy.
Methods: The data of 30 pediatric FMF patients with biopsy-proven glomerulopathy were retrospectively reviewed. Patients were grouped into 2 categories as amyloid nephropathy (AN, n = 16) and non-amyloid nephropathy (N-AN, n = 14).
Results: The mean age at FMF diagnosis was 7.2 ± 3.0 years. The AN group showed higher rates of hypertension, higher levels of 24-h protein excretion and serum creatinine, and lower estimated glomerular filtration rate at the time of kidney biopsy. The rate of ESRD was found to be higher in the AN group (p = 0.011). Mesangioproliferative glomerulonephritis was the most common pathology in the N-AN group (21.4%). The frequency of amyloidosis was significantly higher in patients with homozygous p.M694V mutations than non-homozygous p.M694V mutations (p = 0.039).
Conclusions: In children with FMF, nephropathy is rare. To our knowledge, this is the first study performed in pediatric FMF patients exploring amyloid and non-amyloid glomerulopathies. Patients with AN had higher rates of proteinuria, lower estimated glomerular filtration rate levels, and higher blood pressure than N-AN patients at the time of biopsy.
(© 2020 S. Karger AG, Basel.)