What Are Rare Kidney Diseases?

In the United States, a kidney disease is considered rare if it affects fewer than 200,000 people. There are more than 150 different types of rare kidney diseases, and they can affect people of all ages and backgrounds.¹

How do you get a rare kidney disease?

Many rare kidney diseases are inherited. This means that they are passed down in genes from parents to children. Others are caused by changes in genes, other health issues, or a combination of factors.^1-7

Specific causes of certain kidney diseases can include:^5-7

• Viruses like hepatitis B or C and HIV
• Health conditions such as lupus, sickle cell disease, or even common gastrointestinal (GI) or respiratory illnesses
• Certain medicines or drugs

In some cases, rare kidney diseases are autoimmune in nature. When a person has an autoimmune condition, the body mistakenly attacks itself. In other cases, there may be no known cause.^5-7

What happens in rare kidney diseases?

The kidneys are very important organs in the body. They serve many functions. They help remove and filter waste and other important nutrients. They also help control fluid balance and blood pressure. Also, the kidneys make and concentrate urine.^5,7

Some of these functions are carried out by clusters of tiny blood vessels that act as filters. These are called glomeruli. There are about a million of them in each of your 2 kidneys. Some rare kidney diseases directly affect the glomeruli. When there is inflammation of the glomeruli, it is called glomerulonephritis. When there is scarring of the glomeruli, it is called glomerulosclerosis.^3,5,7

There are also tubules in the kidneys. These tubules help maintain the balance of electrolytes like salt, calcium, and potassium. Some rare kidney diseases affect these tubules and thus the body's electrolyte balance.²

Progression of rare kidney diseases

In people with kidney disease, the kidneys get more damaged over time. This leads to a worsening of symptoms. Symptoms may include:^3,5,7

• Foamy urine that is full of protein
• Blood in the urine
• High blood pressure
• Swelling, especially of the face, hands, feet, or ankles

Eventually, the kidneys become so damaged that they do not work on their own any more. This is called end-stage renal disease or kidney failure. The speed of kidney damage and potential kidney failure varies based on what led to the kidney disease.⁷

Examples of rare kidney diseases

As mentioned, there are more than 150 different types of rare kidney diseases. A few are described below.

IgA nephropathy (IgAN)

People with IgAN have a buildup of IgA in their glomeruli. IgA is a protein that plays a role in the immune system. IgAN can occur along with respiratory or GI infections. It can also cause tiny bruises when it affects the blood vessels in the skin.^5-8

C3 glomerulopathy (C3G)

Complement 3 glomerulopathy (C3G) is a type of membranoproliferative glomerulonephritis (MPGN). C3G has 2 forms – dense deposit disease (DDD) and Complement 3 glomerulonephritis (C3GN).^9-11

In people with C3G, immune system regulation is not normal. Either due to inherited genes or by chance, chemicals are formed that disrupt the function of an important immune system protein called C3 convertase. Abnormal functioning of C3 convertase causes a protein called C3 to build up in the glomeruli and causes problems. In healthy people, C3 is an important protein that helps to fight infections.^9-11

Lupus nephritis

Lupus nephritis is kidney inflammation that results from having lupus. Lupus can cause permanent scarring of the glomeruli. Lupus is one of the most common autoimmune causes of kidney issues and can cause damage in a variety of ways.^5-7

Goodpasture’s disease

People with Goodpasture’s disease make an antibody that attacks healthy tissue in their lungs and kidneys. In addition to kidney related-symptoms, people with Goodpasture’s disease may also cough up blood.^5,7

BK nephropathy

After a person has a kidney transplant, they take drugs that suppress their immune system. The drugs ensure that their body will not reject the new kidney. But when the immune system is weakened, viral infections they have had in the past can reactivate. For example, a common childhood virus called the BK virus can reactive and cause kidney damage.⁴

Renal tubule defects

The renal tubules help with electrolyte balance, so defects in them can cause electrolyte imbalances. Many renal tubule issues are inherited from parents. These include:^2,12

• Fanconi syndrome
• Bartter syndrome
• Gitelman syndrome
• Liddle syndrome

The symptoms of each one can vary based on which electrolytes it affects.^2,12

Polycystic kidney disease (PKD)

Polycystic kidney disease (PKD) is a genetic condition in which cysts, or fluid-filled sacs, grow on the kidneys and other organs. These cysts make it harder for the kidneys to function. PKD can occur in infancy or later in life, depending on the type that is passed down through the family.^2,6

The type of PKD that shows up earlier in life is called autosomal recessive PKD. The type that shows up later in life is called autosomal dominant PKD.^2,6

Alport syndrome

Alport syndrome is a genetic condition that causes a change in a protein called collagen. Collagen is important for healthy kidney function. People with Alport syndrome may also have hearing or vision issues.^2,5,7

Fabry disease

People with Fabry disease cannot make an important protein in the body called alpha- gal A. It is a genetic condition and causes problems with the nervous system, kidneys, and heart.^2,6

Cystinosis

Cystinosis results from the buildup of a chemical called cystine. Too much cystine can lead to the formation of tiny crystals. These crystals cause damage all over the body. This condition is also passed down through families.^2,6

Atypical hemolytic uremic syndrome (aHUS)

Atypical hemolytic uremic syndrome (aHUS) causes damage to the small blood vessels in the body including the tiny clusters of blood vessels in the kidney called the glomeruli. The damaged blood vessels make it easier for tiny clots to form within them causing blockage of blood flow.⁶

Amyloidosis

People with amyloidosis make too much of a protein called amyloid. This protein can build up in different organs and cause major damage. Amyloidosis can affect the heart, liver, nervous system, kidneys, and more.¹³