Alport’s syndrome is a type of autoimmune/collagen disease.
Pathophysiology
1) progressive sclerosis of glomerulus caused by defect in type 4 collagen 2) four forms occur – the most common is the X-linked “classic” form
Signs and Symptoms
1) end stage renal disease by age 40-50 years 2) bilateral anterior conical lens deformation (lenticonus) 3) cataracts 4) corneal abrasions 5) 50% sensorineural hearing loss (initially high-frequency deafness 6) hypertension
Characteristic Test Findings
Laboratory – 1) hematuria from infancy 2) proteinuria
Histology/Gross Pathology
1) defective thickened basement membrane structure with layering and splitting 2) hypercellular glomerulus 3) interlacing lamellae in glomerular basement membrane
Associated Conditions
1) renal failure in adolescence 2) greatly increased risk of developing Goodpasture’s syndrome
Biochemistry
defect in collagen type IV alpha-5 gene (COL4A5)
Inheritance/Epidemiology
1) classic X-linked inheritance form affects 1/10,000 2) female carriers have mild disease and do not develop renal insufficiency
Treatment
definitive treatment is renal transplantation (Alport’s can recur in the graft)
Tips for USMLE
1) lenticonus (bilateral anterior conical displacement of the lens) is pathognomonic for Alport’s syndrome 2) if question mentions cataracts, kidney damage, and hearing loss in a young man, or defect in type IV collagen, think Alport’s
Leave a Reply