- Clinical science
Alport syndrome is a genetic disorder that is characterized by glomerulonephritis, often in combination with sensorineural hearing loss and sometimes eye abnormalities. It is caused by a genetic defect of type IV collagen, which is usually inherited in an X-linked pattern and therefore mostly affects boys. Patients typically present with intermittent gross hematuria during infancy. In adolescence, patients classically start to develop more serious signs of chronic kidney disease (e.g., proteinuria), and may experience hearing loss or, in rare cases, vision problems. In milder forms, patients may remain asymptomatic and only require monitoring. In classic Alport syndrome, diagnostic evaluation shows persistent microhematuria on urinalysis and splitting of the glomerular basement membrane on kidney biopsy. The classic form usually leads to end-stage renal disease (ESRD) between the second and third decade of life, and the only definitive treatment is a kidney transplant.
- Rare disorder (but it is the most common hereditary nephritis)
Age of onset
- Hematuria may present in infancy
- Severe disease typically presents during adolescence, although some milder forms may have late onset or remain subclinical.
Epidemiological data refers to the US, unless otherwise specified.
- Often asymptomatic
- Initially intermittent gross hematuria
- As glomerular damage progresses → symptoms of nephritic syndrome and chronic kidney disease (usually leads to ESRD between the ages of 16 and 35)
- Sensorineural hearing loss (∼ 60% of cases)
- Ocular findings () (∼ 25% of cases)
Patients with Alport syndrome can't pee, can't see, can't hear a bee!
- Laboratory tests
- Skin biopsy: confirmatory test, absence of collagen type IV alpha-5 chains
- Light microscopy: mesangial cell proliferation and sclerosis
- Electron microscopy: splitting and alternating thickening and thinning of the glomerular basement membrane (“basket-weave appearance”)
- Immunostaining: absence of the type IV collagen alpha-3, alpha-4, and/or alpha-5 chains in the basement membrane
- Molecular genetic testing: can confirm and distinguish subtypes
- Patients diagnosed with Alport's should regularly undergo:
- Monitor renal function regularly
- In patients with proteinuria : ACE inhibitors/angiotensin II receptor blockers
- As disease progresses to renal failure: see management of diuretics) (e.g., sodium restriction,
- A kidney transplant is the only definitive treatment of Alport syndrome.
- hearing loss in patients with
- Consider surgery in patients with lenticonus