Key takeaways

  • Immunoglobulin A (IgA) nephropathy, also called Berger disease, is a rare autoimmune kidney disease. It is also a leading cause of kidney failure.
  • Most cases are sporadic, and scientists do not know the exact cause. Fewer than 10% are familial, and genome studies suggest about 30 gene locations may affect risk.
  • Familial Immunoglobulin A nephropathy (IgAN) can follow an autosomal dominant pattern, giving a child a 50% chance of inheriting a mutation. Risk is higher in people of Asian descent, ages 10 to 40, and those with certain conditions; talk with a doctor if you have a family history.

Immunoglobulin A (IgA) nephropathy, aka Berger disease, is a rare autoimmune disease that affects your kidneys. Though rare, IgA nephropathy (IgAN) is one of the leading causes of kidney failure.

More than 90% of IgA cases are sporadic, meaning they develop due to changes your body experiences during your lifetime. Scientists still aren’t sure of the exact causes of these cases.

But the remaining cases (less than 10%) are familial, meaning you’ve inherited genetic changes (mutations) from your parents that increase your risk of developing IgAN.

Genome studies have identified as many as 30 specific gene locations that may affect a person’s risk of developing IgAN. These genes code for proteins and enzymes that perform specific functions. Mutations in these genes can affect the function of those proteins.

Scientists think IgAN is polygenic in nature, meaning it takes mutations in several of these genes to cause the disease. Still, they estimate that these genes only account for about 11% of IgAN risk.

Genes linked specifically to familial IgAN include:

  • IGAN1 on chromosome 6
  • IGAN2 on chromosome 2
  • SPRY2 on chromosome 13

Genes linked to familial IgAN appear to follow an autosomal dominant inheritance pattern. That means if a parent has the genetic mutation, they have a 50% chance of passing it on to their child.

However, that doesn’t mean the child will necessarily develop IgAN. The genetic mutation increases the risk, but not everyone with the mutation develops the disease. This is called incomplete penetrance.

Studies estimate the heritability of IgAN to be between 40% and 50%.

IgAN is rare, with only about 25 new diagnoses per every 1 million people worldwide, though rates vary considerably by region. It’s much more common in Far East Asia than in Europe or North America. It’s much less common in Africa, though research is sparse.

Due to its genetic component, race and ethnicity may play a role in IgAN risk. Studies suggest that people of Asian descent are more likely to develop IgAN than people of European or African descent.

Other risk factors include:

People typically develop IgA between the ages of 10 and 40, although symptoms may not appear for several years. Talk with a doctor if you’re at high risk and have a family history of IgAN.