Often mistaken for Chronic Kidney Disease (CKD), Rare Kidney Disease (RKD) is a set of uncommon conditions many times caused by genetics or autoimmune conditions. For a kidney disease to be considered “rare”, it must affect less than 1 per 2000 people. In comparison, CKD refers to a more broad category that defines one’s kidneys as damaged or not working well for three or more months. Focal Segmental Glomerulosclerosis, or FSGS, is a form of rare kidney disease, that most commonly impacts us.
CKD is extremely common, affecting at least 10% of adults around the world and according to the Centers of Disease Control (CDC) 20% of NonHispanic African Americans have it. It is often caused by diabetes, aging, high blood pressure, or long-term infections. Black Americans are disproportionately affected by kidney disease overall and it is important to understand the variations of this disease. It can mean the difference between early detection and life-saving treatment or End Stage Kidney Failure.
How Do You Diagnose CKD vs RKD?
Because of the more common nature of CKD, testing can often be done by your primary care physician. The National Institute of Diabetes and Digestive and Kidney Disease shares that these tests may include:
- Blood Test
- Urine Test
- Monitor testing over 3 or more months to document the progression of kidney function
For RKD, testing is more specialized and can require more investigation by a nephrologist or other specialist. According to raredisease.net, these tests may include:
- Genetic Testing
- Specialized blood test
- Advanced Urine Testing
- Kidney Biopsy
- Advanced Imaging
Rare disease is regularly missed because these tests are more expensive, less available or require a specialist referral. Also, physicians sometimes stop at a CKD diagnosis and do not seek further testing or information. It is very important to be your own advocate to ensure that you receive the proper diagnosis and subsequent treatment. Having the correct diagnosis matters because it can change your:
- Treatment choice
- Prognosis (how fast disease may progress)
- Family screening
- Transplant decisions
- Clinical trial eligibility
Why does this difference matter?
Symptoms of RKD are often not as specific and can make diagnosing the disease more difficult. Many types of RKD require a kidney biopsy or genetic testing. This can be challenging and cause delays in diagnosis. Treatment also can be limited and specialized. It is important to recognize some common symptoms like:
- Swelling in the face, hands, or legs,
- Blood or protein in urine
- Fatigue
- High blood pressure
- Reduced urine output
Though these symptoms are broad, they can be good indicators of how your kidneys are functioning and help to initiate a larger conversation with your provider about getting tested for RKD. The goal is to always try to preserve one’s kidney function and to slow or stop kidney disease progression and the key to this is earlier detection.
CKD is the most common form of kidney disease but knowing it is not the only form could help save yours or a loved ones kidneys.
FSGS: A form of Rare Kidney Disease that Black Americans Should Know About
Focal Segmental Glomerulosclerosis, or FSGS, disproportionately impacts our community. According to Nepchure.org, Black Americans are five times more likely to develop it in comparison to the general population.
Our kidneys contain millions of tiny filters called glomeruli and with the presence of FSGS, some of those filters become scarred preventing them from working properly. This process left untreated can lead to CKD and kidney failure. When the kidney filters are damaged:
- Protein leaks into the urine (proteinuria)
- Swelling (edema) occurs in the legs, face, or abdomen
- Blood protein levels drop
- Cholesterol levels rise
According to the Mayo Clinic, several types of FSGS include:
- Primary FSGS- when there is no known cause for their condition.
- Secondary FSGS- may be caused by infections like HIV and Hepatitis C, drug toxicity, diseases like diabetes or sickle cell disease, obesity, and even other kidney diseases can cause secondary FSGS.
- Genetic FSGS- a rare form of FSGS caused by genetic changes.
FSGS is important to highlight because many people, even some non-specialist, do not know about this form of RKD. As of today, much research is being done but Nephcure.org shares that there are currently no FDA approved treatments for it and 50% of FSGS patients will progress to kidney failure. With what is available and commonly used to treat it, the goals are to stop spilling protein completely, which would be considered remission, or lower the amount of protein lost in the urine as much as possible to prevent relapse and further kidney deterioration.
Keisha L. Gibson, MD MPH FASN, Professor of Pediatrics, Senior Vice Chair of Clinical Affairs, Dept. of Pediatrics, and Chief of Pediatric Nephrology at University of North Carolina Kidney Center says “While there isn’t a cure for FSGS [yet], we do have treatments that can significantly slow kidney damage. Managing things like blood pressure, diabetes, and diet—along with medications that help prevent kidney scarring—can help delay or even prevent the need for dialysis or a transplant.”.
Genetics and the Role They Play
Apolipoprotein L1, or APOL1, is a gene found in every person, one copy of the gene being inherited from each parent. The American Kidney Fund shares that “the APOL1 gene makes a protein in your immune system which is your body’s cells and tissues that fight infection.” But it has been discovered that this gene can mutate and cause a rare form of kidney failure over time, these variants being found most common in people of African ancestry.
Dr. Gibson agrees, “APOL1 is an important driver of kidney disease in those of us that have recent African ancestry. While it’s not a guarantee that people with APOL1 variants will develop kidney disease, the risk is certainly much higher.”
According to NephCure.org, 1 in 8 African Americans are at risk for this genetic form of kidney disease. As the community most affected by kidney disease, this is significant. About 40% of African Americans who are on dialysis have kidney failure caused by APOL1. And though there is no FDA approved treatment for this genetic form of kidney disease, it is important to know if your slowed kidney function is due to APOL1. The only way to learn if you have this mutation is through genetic testing, but knowing this will better help to inform your care team on what available treatments might be best and the proper route of care for you.
Dr. Gibson believes that, “Knowing your APOL1 status not only may prompt you to make sure you’re getting regular check-ups to catch any early signs of disease and take control of the things you can control (blood pressure, diabetes, weight, etc.), but it may also help you advocate for the same for your family members that may also be at risk.”
Stay Informed
There is much more to know and understand about FSGS, APOL1 and other forms of RKD, but one’s first line of defense is having a general understanding of what rare kidney disease is, signs and symptoms that you may have and being aware of the types of RKD that impact your community the most. Bring up any concerns you may have with your doctor. Do not hesitate to ask for specific testing and when in doubt, do your research.
