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# Alport syndrome

Alport syndrome is an inherited collagen disease that damages the kidney filters, the inner ear and the eye. It often leads to kidney failure in young adults.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Kidneys](https://durgical.com/en/anatomy/kidney/)
- [Vessels inside the kidney](https://durgical.com/en/anatomy/intrarenal-arteries-and-veins/)
- [Cochlea](https://durgical.com/en/anatomy/cochlea/)
- [Lens](https://durgical.com/en/anatomy/lens/)
- [Retina](https://durgical.com/en/anatomy/retina/)
- [Cornea](https://durgical.com/en/anatomy/cornea/)

## Why it happens

- [Mendelian inheritance: autosomal dominant, recessive and X-linked](https://durgical.com/en/general-pathology/mendelian-inheritance-autosomal-dominant-recessive-and-x-linked/)
- [How a single gene causes disease: enzymes, receptors and structural proteins](https://durgical.com/en/general-pathology/how-a-single-gene-causes-disease-enzymes-receptors-and-structural-proteins/)
- [Collagen](https://durgical.com/en/biochemistry/enzymes/collagen/)
- [Basement membrane](https://durgical.com/en/histology/basement-membrane/)
- [Glomerulus and the filtration barrier: podocytes, mesangium, JGA](https://durgical.com/en/histology/glomerulus-and-the-filtration-barrier-podocytes-mesangium-jga/)

## What it is

An inherited disorder of type IV collagen in basement membranes that causes progressive glomerular disease with haematuria, together with sensorineural hearing loss and eye changes. Thin basement membrane disease is a milder carrier-type form at the same genes.

## Who gets it

A rare disease (about 1 in 50,000 births) but a classic cause of inherited haematuria and of kidney failure in adolescents and young adults, including in Latin America. The X-linked form is the most common and males are hit hardest; it is underdiagnosed where genetic testing and kidney biopsy are hard to obtain.

## Causes

- Pathogenic variants in COL4A5 (X-linked, about two thirds of cases)
- Variants in both copies of COL4A3 or COL4A4 (autosomal recessive)
- A single variant in COL4A3 or COL4A4 (autosomal dominant; overlaps with thin basement membrane disease)

## Risk factors

- Family history of haematuria, kidney failure or deafness, especially in males of the maternal line
- Male sex in the X-linked form
- Consanguinity (autosomal recessive form)

## Pathophysiology

The alpha-3, -4 and -5 chains of type IV collagen form the network of the glomerular basement membrane, the [cochlea](https://durgical.com/en/anatomy/cochlea/) and the lens capsule. When one chain is missing the membrane stays immature, thins, splits and frays, so red cells leak into the urine. Over years the glomeruli scar and kidney function falls; the same defect in the inner ear and eye causes hearing loss and lens deformity.

## Classification

- X-linked Alport syndrome (COL4A5): males severe, female carriers variable
- Autosomal recessive Alport syndrome (COL4A3/COL4A4): severe in both sexes
- Autosomal dominant Alport syndrome (COL4A3/COL4A4): milder and later
- Thin basement membrane disease: isolated persistent microscopic haematuria, usually benign

## Symptoms and signs

- Persistent microscopic haematuria from childhood, often the first sign
- Episodes of visible (gross) haematuria with respiratory infections or exercise
- Proteinuria that appears and grows with age, then hypertension and oedema
- Bilateral sensorineural hearing loss, often starting in late childhood or adolescence
- Eye findings: anterior lenticonus (cone-shaped lens), dot-and-fleck retinopathy, corneal erosions, early cataract

## Red flags

- Haematuria with rising creatinine or proteinuria in a child or young adult
- Haematuria plus hearing loss, or a relative with kidney failure and deafness
- Signs of advanced kidney failure: severe oedema, breathlessness, very high blood pressure or high potassium
- Haematuria, haemoptysis or a sharp creatinine rise after a kidney transplant (anti-GBM disease against the new kidney)

## Diagnosis

**Clinical**
Persistent haematuria with a family history, hearing loss or eye findings. A three-generation family history and examination of relatives are key.

**Tests**
Urinalysis with dysmorphic red cells, urine albumin- or protein-to-creatinine ratio, creatinine with eGFR. Genetic testing of COL4A3, COL4A4 and COL4A5 is the preferred confirmation. [Kidney](https://durgical.com/en/anatomy/kidney/) biopsy shows thinning, splitting and a basket-weave pattern of the glomerular basement membrane on electron microscopy, with abnormal collagen IV staining. Audiometry and an eye examination complete the work-up.

**Imaging**
Kidney ultrasound to assess size and exclude other causes of haematuria; slit-lamp examination for anterior lenticonus.

## Differential diagnosis

- IgA nephropathy
- Thin basement membrane disease without progression
- Post-infectious glomerulonephritis
- Anti-glomerular basement membrane disease (Goodpasture)
- Urological causes of haematuria such as stones or tumours

## Goal of treatment

Slow the loss of kidney function by lowering proteinuria and blood pressure, support hearing and vision, prepare in time for dialysis or transplantation, and offer genetic counselling to the family.

## Treatment

**Medical**
ACE inhibitors (or ARBs if not tolerated), started early once albuminuria appears, slow progression and delay kidney failure; other kidney-protective classes may be added.

**Lifestyle**
Salt restriction, avoiding nephrotoxic drugs, not smoking and, in later stages, the kidney diet for chronic kidney disease.

**Follow-up**
Regular urine protein, creatinine with eGFR, blood pressure, audiometry and eye checks; screening of at-risk relatives, including female carriers.

**Conservative**
Hearing aids for hearing loss; [lens](https://durgical.com/en/anatomy/lens/) surgery for symptomatic lenticonus or cataract.

**Surgical**
Dialysis and kidney transplantation at kidney failure; the disease does not recur in the graft, but anti-GBM disease against the transplant can occur rarely.

## Complications

- Progressive chronic kidney disease and kidney failure, often before 30–40 years in X-linked males
- Hypertension and its cardiovascular effects
- Permanent bilateral hearing loss
- Visual problems from lenticonus, cataract or macular holes
- Anti-GBM nephritis after kidney transplantation (rare)

## Prognosis

Depends on sex and genetic form: most X-linked males and recessive patients reach kidney failure in early adulthood, while female carriers and dominant forms progress more slowly. Early blockade of the renin–angiotensin system clearly delays kidney failure, and transplant outcomes are good.

## Prevention

- Genetic counselling and cascade testing of relatives
- Early urine testing in children of affected families to start kidney protection in time

## Test yourself

Think of the answer, then tap the question to see it.

## Which collagen and genes are affected in Alport syndrome?

Type IV collagen: COL4A5 (X-linked, most common), and COL4A3 or COL4A4 (autosomal recessive or dominant).

## What is the classic triad of Alport syndrome?

Glomerular haematuria progressing to kidney failure, bilateral sensorineural hearing loss and eye changes such as anterior lenticonus.

## What does electron microscopy of the glomerular basement membrane show in Alport syndrome?

Irregular thinning and thickening with splitting of the lamina densa, giving a basket-weave appearance.

## Which drug class is used early to slow kidney progression in Alport syndrome?

ACE inhibitors (or ARBs), which lower proteinuria and delay kidney failure.

## What rare complication can follow kidney transplantation in Alport syndrome?

Anti-glomerular basement membrane disease, because the graft carries collagen IV chains the immune system has never seen.

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## Related conditions

- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)
- [Hearing loss (conductive and sensorineural, including sudden hearing loss)](https://durgical.com/en/conditions/hearing-loss/)
- [Cataract](https://durgical.com/en/conditions/cataract/)
- [IgA nephropathy](https://durgical.com/en/conditions/iga-nephropathy/)
- [Post-streptococcal glomerulonephritis](https://durgical.com/en/conditions/post-streptococcal-glomerulonephritis/)
- [Nephrotic syndrome](https://durgical.com/en/conditions/nephrotic-syndrome/)
- [Arterial hypertension](https://durgical.com/en/conditions/arterial-hypertension/)
- [Kidney transplant rejection](https://durgical.com/en/conditions/kidney-transplant-rejection/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Alport syndrome: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/alport-syndrome/) (MedlinePlus (U.S. National Library of Medicine), 2024); [Alport syndrome: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000504.htm) (MedlinePlus (U.S. National Library of Medicine), 2024).

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Source: https://durgical.com/en/conditions/alport-syndrome/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/alport-syndrome/