An unusual association between familial Mediterranean fever and IgM nephropathy

Objective: To report a case with the diagnosis of IgM nephropathy and familial Mediterranean fever (FMF). Clinical Presentation and Intervention: A 9-year-old boy was admitted to our hospital with recurrent abdominal pain since the age of 4 years. Laboratory investigations revealed a sedimentation rate of 88 mm/h, C-reactive protein: 83.2 mg/l (0-10 mg/l), white blood cell count: 12,700/mm³, fibrinogen: 622 mg/dl (200-400 mg/dl) and serum amyloid A: 186 mg/l (0-5.8 mg/l). Urinalysis revealed +2 proteinuria. A 24-hour urinary protein excretion was 12 mg/m²/h. M694V homozygous mutation was identified in exon 10. Percutaneous renal biopsy showed mesangial cell proliferation and increased mesangial matrix in the glomeruli, without amyloid accumulation. Immunofluorescence study showed IgM (+1) and C1q (+1) deposits. Treatment with 1 mg/day colchicine was started. Six weeks later, proteinuria had disappeared and the patient was asymptomatic. Conclusion: This case illustrates the unusual association of FMF with non-amyloid glomerulopathy. Glomerular diseases such as IgM nephropathy may be seen as a manifestation of FMF.