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Alport’s Syndrome

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Overview

Alport’s syndrome (AS) is a genetic disorder that is mostly inherited in an x-linked dominant pattern, however, may also be inherited in an autosomal recessive fashion. It is caused by an inherited defect in type IV collagen, which is found in the ears, eyes, and kidneys. It can lead to chronic kidney disease (CKD).

Epidemiology

  • X-linked recessive (COL4A5) inheritance makes up around 85% of cases
  • Autosomal recessive (COL4A3/4) inheritance makes up around 15% of cases
  • Rarer autosomal dominant cases have been noted – around 1%
  • Males are more severely affected than females

Presentation

AS generally presents in childhood. Features include:

  • Microscopic haematuria
  • Proteinuria
  • Bilateral sensorineural deafness
  • Lenticonus – bulging of the lens capsule

Investigations

  • Urinalysis and microscopy:
    • Microscopic/macroscopic haematuria is the earliest and commonest sign of AS
    • Proteinuria worsens with age
    • May show red blood cells and red cell casts
  • Renal biopsy:
    • Light microscopy: mesangial cell proliferation and capillary wall thickening
    • Electron microscopy: glomerular basement membrane lamina densa splitting and lamellation
  • Audiometry:
  • Molecular genetic testing:
    • Identifies mutations

Management

There is no definitive treatment for AS. Management involves:

  • ACE inhibitors – reduce proteinuria and renal disease progression
  • Management of CKD

Complications

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