Background: Hereditary fibrinogen A alpha-chain (AFib) amyloidosis affects different organs, especially the kidneys. No case of this disease has been reported in Latin America.
Case report: A 52-year-old previously healthy Brazilian woman presented with a seven-month history of proteinuria in the absence of hematuria. The patient had normal blood pressure and reported no other symptoms. A renal biopsy was obtained and light microscopy revealed the presence of Congo red positive deposits (apple-green birefringence under polarized light) only in the glomerular compartment. These deposits were strongly immunoreactive to fibrinogen in all glomeruli. Electron microscopy showed the presence of organized deposits compatible with AFib. The diagnosis was confirmed by DNA analysis of the AFib gene, which demonstrated a Glu526Val mutation in one allele.
Conclusion: This first description of hereditary AFib amyloidosis in Latin America highlights the need to include this type of amyloidosis in the differential diagnosis, especially in Brazil where the degree of miscegenation is high.