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Please prepare and upload your E-Poster no later than March 14, 2026 11.59PM CET. After this date, you will no longer be able to prepare and upload your E-poster and it will not be displayed and accessible on the congress website.
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Abstract titles should be brief and reflect the content of the abstract.
Type IV collagen is a principal structural component of the glomerular basement membrane (GBM). Pathogenic variants in COL4A3, COL4A4, and COL4A5 cause Alport syndrome. Recent genomic studies indicate that these variants also underline a spectrum of hereditary kidney diseases, including focal segmental glomerulosclerosis (FSGS).
A 36-year-old woman with hypertension and hyperuricemia presented with several weeks of new-onset bilateral lower-leg edema. Her paternal grandmother, older sister, and three nieces had a history of hematuria. Until recently, only microscopic hematuria had been noted; proteinuria was first detected at a routine health examination, and four month later lower leg edema developed, prompting referral to our hospital. Urinalysis showed 20–29 red blood cells/high-power field and proteinuria of 11.3 g/gCr; serum creatinine was 0.95 mg/dL and albumin of 1.8 g/dL, consistent with hematuria and nephrotic syndrome. Given the subacute course, she underwent steroid pulse therapy and renal biopsy. Renal pathology was consistent with FSGS. Cyclosporine was added, and low-density lipoprotein (LDL) apheresis was performed four times; however, proteinuria persisted. Genetic testing identified a heterozygous COL4A4 variant (p.Gly894Glu) classified as likely pathogenic according to ACMG/AMMP criteria. Electron microscopy demonstrated GBM thinning without the typical Alport features like irregular thickening or lamellation. The rapid progression to nephrotic syndrome and absence of hearing or ocular impairment were atypical for classic Alport syndrome. Immunosuppressive therapy was continued for approximately four years after the onset of nephrotic syndrome without remission. In light of the diagnosis of hereditary nephritis, the immunosuppressive treatment was gradually tapered and discontinued.
To our knowledge, this is the first report of sudden-onset nephrotic syndrome attributable to a type Ⅳ collagen gene variant. Genetic testing has expanded the spectrum of type Ⅳ collagen-related nephropathies beyond classical Alport syndrome, encompassing entries such as hereditary FSGS. We observed intrafamilial phenotypic variability among two sisters with the same COL4A4 variant: the elder had isolated hematuria without proteinuria or renal dysfunction, whereas the younger had proteinuria (～1g/gCr) and reduced kidney function (creatinine 1.8 mg/dL). This variability suggests that additional genetic modifiers or environmental factors influence disease expression. Taken together, these cases underscore the clinical heterogeneity and complexity of type Ⅳ collagen-associated kidney disease.
Even in adult-onset, treatment-resistant FSGS, genetic testing including COL4A3-COL4A5 can provide diagnostic and prognostic insight. Recognizing the broader clinical spectrum of COL4-related nephropathy may improve patient management and genetic counseling.
