Thin Basement Membrane Disease
Helen Liapis, MD
Joseph Gaut, MD, PhD
Key Facts
Clinical Issues
Presents with persistent microscopic hematuria
Autosomal dominant inheritance
1-5% of population
Microscopic Pathology
Minimal changes
Ancillary Tests
Immunofluorescence
Preserved α3, α4, and α5 (IV) collagen
Normal expression does not definitively exclude AS
Electron microscopy
Uniform GBM thinning (< 200 nm)
Genetic testing
Mutations in COL4A3 or COL4A4 genes
Top Differential Diagnoses
Alport syndrome
IgA nephropathy
 This PAS stained slide from a woman with thin basement membrane disease (TBMD) shows a normal glomerulus, typical of TBMD by light microscopy. The GBM averaged 230 nm by electron microscopy. |
 Electron microscopy in TBMD reveals a diffusely thin but otherwise normal GBM of < 200 nm (normal is 320 ± 50 nm in females, 370 ± 50 nm in males). Morphometry is recommended to assess the thickness of the GBM. |
TERMINOLOGY
Abbreviations
Thin basement membrane disease (TBMD)
Synonyms
Benign familial hematuria (BFH)
Definitions
Autosomal dominant disorder presenting with asymptomatic microscopic hematuria characterized by diffuse GBM thinning
ETIOLOGY/PATHOGENESIS
Genetics
Autosomal dominant in majority of BFH
Rare mutations in collagen α3 and α4 (IV)
40% of patients with GBM thinning have mutations in COL4A3 or COL4A4 genes
Encode α3 and α4 chains of type IV collagen, respectively
Heterozygotes, typically women
Autosomal recessive Alport syndrome (ARAS)
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