Persistent Isolated Hematuria in a Japanese Woman

A 43-year-old Japanese woman, with a family history of hematuria, underwent a kidney biopsy because of persistent hematuria without proteinuria, with serum creatinine of 0.55 mg/dl. Light microscopy revealed minor glomerular abnormalities. Electron microscopy predominantly showed thinning of the glomerular basement membrane (GBM); thickening and lamination were observed in small portions of the GBM (Figure 1A). Atypical Alport syndrome (AS) was suspected. Type IV collagen staining revealed weak α5(IV) expression with enhanced expression of α2(IV) in segmental lesions, consistent with AS (Figure 1, B and C). This case was presumed to be autosomal dominant AS (ADAS), because of the family history and preserved α5(IV) expression in the Bowman’s capsule, which indicate the mutation of COL4A3 or COL4A4 (Figure 1C) (1). Diagnosis of typical AS, namely, X-linked AS in males and autosomal recessive AS, is straightforward, and often made in childhood. In contrast, ADAS is usually suspected in adults because …