Disorder of type IV collagen matrix

Aetiology

• X-linked mutation in COL4A5 gene leads to deficient collagenous matrix deposition

Clinical feature

• Suspect in patients with microscopic haematuria +/- hearing loss in the early years
• Haematuria is the characteristic feature
• Proteinuria seen later but confers bad prognosis
• Extra renal manifestations:
  • Sensorineural deafness
  • Ocular defects - anterior lenticonus
  • Leiomyomatosis of oesophagus/genitalia - rare

Investigations

• Renal biopsy: variable thickness of the glomerular basement membrane is the characteristic feature
  • Due to splitting of the lamina densa

Management

• No specific treatment
• Standard aggressive treatment of BP, proteinuria
• Dialysis/transplantation