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Alport syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Alport syndrome

Alport syndrome is a genetic condition that causes progressive kidney disease, hearing loss, and eye abnormalities.

Overview

Alport syndrome is characterized by the progressive loss of kidney function. Almost all affected individuals experience blood in the urine (hematuria), and many develop high levels of protein in the urine (proteinuria). Over time, this leads to end-stage kidney disease (ESKD).

Symptoms

  • Kidney Disease: Progressive decline in the ability to filter waste, eventually leading to kidney failure.
  • Hearing Loss: Sensorineural hearing loss often develops in late childhood or early adolescence due to abnormalities in the inner ear.
  • Eye Abnormalities: These include misshapen lenses (anterior lenticonus) and abnormal coloration of the retina. These issues rarely lead to vision loss.

Causes

The condition is caused by variants in the COL4A3, COL4A4, and COL4A5 genes. These genes are responsible for producing components of collagen IV, a protein essential for the structure of the glomeruli (kidney filters), the inner ear, and the eyes. Abnormal collagen IV prevents the kidneys from filtering blood properly and impairs the function of the inner ear and eye structures.

Inheritance

Alport syndrome follows three distinct inheritance patterns:

  • X-linked (approx. 66% of cases): Caused by variants in the COL4A5 gene. Males are typically more severely affected than females.
  • Autosomal Recessive (approx. 15% of cases): Caused by variants in both copies of the COL4A3 or COL4A4 gene.
  • Autosomal Dominant (20–30% of cases): Caused by a single variant in the COL4A3 or COL4A4 gene.

It is often difficult to distinguish between mild Alport syndrome and a related condition called thin basement membrane nephropathy, which is also characterized by hematuria.

Frequently Asked Questions

udiologic screening should begin in early childhood, ideally before age 5, because sensorineural hearing loss can develop in late childhood or early adolescence. Early identification allows timely hearing aids or cochlear implants, which can improve speech and learning outcomes.
definitive diagnosis often requires a kidney biopsy showing characteristic thinning and splitting of the glomerular basement membrane, along with genetic testing for COL4A3, COL4A4, or COL4A5 mutations. Urinalysis for hematuria and proteinuria, blood pressure monitoring, and renal function tests are also essential.
ngiotensin‑converting enzyme inhibitors or angiotensin receptor blockers are first‑line treatments to reduce proteinuria and slow decline. Maintaining a low‑salt diet, controlling blood pressure, avoiding nephrotoxic drugs (e.g., NSAIDs), and staying well hydrated can also help preserve kidney function.
Because Alport can be X‑linked, autosomal recessive, or autosomal dominant, genetic counseling is crucial. Couples can undergo carrier testing, prenatal diagnosis, or preimplantation genetic testing to understand risks for future children. A genetic counselor can explain the specific inheritance pattern based on the identified mutation and guide reproductive decisions.===
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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