Children's Hospital Colorado

Alport Syndrome

What is Alport syndrome?

Alport syndrome is a condition affecting the kidneys that results in blood and extra protein in the urine and often leads to decreased kidney function over time. This decrease in kidney function can be severe enough to eventually require dialysis or kidney transplantation. Alport syndrome can also affect the eyes and ears, which can result in some degree of hearing loss.

What causes Alport syndrome?

Alport syndrome is caused by a genetic mutation that can be passed down through the parents. The affected gene that causes Alport syndrome, COL4A5, helps to create proteins that form the filters in the kidneys. The same protein, collagen, is also used to create tissues in the eyes and ears, which is why Alport syndrome can also affect them.

Who gets Alport syndrome?

The gene mutations responsible for the development of Alport syndrome are found on the X chromosome. Because males only have one copy and females have two, females have a better chance of having at least one healthy X chromosome. That means that Alport syndrome mostly affects males and it affects them more severely than females. While females can "carry" the mutation and it may affect them mildly, it is rare to see severe cases of Alport syndrome in females.

Based on how the X chromosome is affected, Alport syndrome is divided into three separate genetic types:

  • X-linked Alport syndrome (XLAS) is the most common. In this type, affected males typically have more severe cases than affected females.
  • Autosomal recessive Alport syndrome (ARAS) is the second most common. In this type, the severity of disease in affected males and females is similar.
  • Autosomal dominant Alport syndrome (ADAS) is the least common. In this type, the disease is severe and affects males and females equally.