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COL4A5 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

COL4A5 gene

The COL4A5 gene is responsible for producing the alpha5(IV) chain of collagen IV, a protein essential for the structural integrity of basement membranes in the kidneys, inner ears, and eyes.

Normal Function

The COL4A5 gene provides instructions for making one piece of a protein called collagen IV. Specifically, this gene makes the alpha5(IV) chain of collagen IV. This chain combines with two other types of alpha (IV) chains (the alpha3 and alpha4 chains) to make alpha345(IV) collagen molecules. These molecules attach to each other to form complex protein networks that make up a large portion of basement membranes, which are thin, sheet-like structures that separate and support cells in many tissues. Alpha345(IV) collagen networks play an especially important role in the basement membranes of the kidney, inner ear, and eye.

Health Conditions Related to Genetic Changes

Alport syndrome

Many variants (also called mutations) in the COL4A5 gene can cause Alport syndrome, a condition characterized by kidney disease, hearing loss, and eye abnormalities. Most of these variants change single protein building blocks (amino acids) in a region where the alpha5(IV) collagen chain combines with other collagen IV chains. Other variants in the COL4A5 gene severely decrease or prevent the production of alpha5(IV) chains.

These changes in the structure or amount of alpha5(IV) chains severely impair the formation of alpha345(IV) collagen networks in the basement membranes of the kidney, inner ear, and eye. In the kidney, other types of collagen build up in the basement membranes, eventually scarring the kidneys and leading to kidney failure. Variants in this gene can also lead to hearing loss and changes in the lens of the eye and the light-sensitive tissue at the back of the eye (retina).

Other Names for This Gene

  • ASLN
  • ATS
  • CA54
  • CO4A5_HUMAN
  • collagen IV, alpha-5 polypeptide
  • collagen of basement membrane, alpha-5 chain
  • collagen type IV alpha 5
  • collagen, type IV, alpha 5
  • collagen, type IV, alpha 5 (Alport syndrome)

Frequently Asked Questions

Because COL4A5 is X‑linked, each son has a 50 % chance of inheriting the mutated X chromosome and will likely develop classic Alport syndrome; each daughter has a 50 % chance of being a carrier like you. Prenatal options include chorionic villus sampling (10–12 weeks) or amniocentesis (15–18 weeks) for targeted genetic testing of the COL4A5 mutation. Pre‑implantation genetic testing (PGT‑M) with IVF is another way to select embryos without the mutation. Discuss these options with a genetic counselor and maternal‑fetal medicine specialist early in pregnancy planning.
The COL4A5 gene is on the X chromosome. Males have only one X chromosome, so a single pathogenic COL4A5 mutation means every cell produces the abnormal collagen chain, leading to classic Alport syndrome with early‑onset kidney failure, hearing loss, and eye problems. Females have two X chromosomes; the normal copy can partially compensate because of random X‑inactivation, so many women experience milder symptoms (often just hematuria) and later onset of kidney disease, though some can develop significant disease.
Guidelines suggest: • Kidney: serum creatinine/eGFR and urine protein check every 6 months (more often if proteinuria or declining eGFR). • Blood pressure at each visit, aiming for <130/80 mm Hg. • Hearing: baseline audiogram at diagnosis, then annually or sooner if you notice changes. • Ophthalmology: comprehensive eye exam (including slit‑lamp and retinal imaging) at diagnosis and every 1–2 years. Adjust intervals if any test shows progression.
Yes. Multiple studies show that starting an ACE inhibitor (or ARB) early—once proteinuria or even micro‑hematuria is detected—delays the rise in serum creatinine and postpones the need for dialysis or transplant by several years. The benefit is dose‑dependent, so titrate to the maximum tolerated dose while monitoring potassium and kidney function. Other supportive measures (low‑salt diet, avoidance of nephrotoxins) are also important.
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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