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Focal Segmental Glomerulosclerosis (FSGS)

About FSGS

FSGS is a rare disease that attacks the kidney’s glomeruli and podocytes, causing scarring which leads to permanent kidney damage.

This damage can lead to kidney failure requiring people with FSGS to undergo dialysis and/or a kidney transplant. Each kidney is made up of ~1 million tiny filters called glomeruli. When glomeruli become damaged or scarred (sclerosis), proteins begin leaking into the urine (proteinuria). The word “focal” means that only some of the glomerular filters become scarred and “segmental” means that only some sections of the glomerulus become scarred.

What are the symptoms of FSGS?

The onset of FSGS can occur at any age, depending on the underlying cause. The hallmark sign of FSGS is proteinuria. As proteinuria progresses, people with FSGS may experience severe swelling around the eyes, hands and feet, and abdomen causing sudden weight gain. Those with FSGS often feel exhausted, even after relatively simple tasks. Other symptoms of FSGS include low blood albumin, high cholesterol, and high blood pressure.

What causes FSGS?

TRPC5-Rac1 pathway dysfunction is a key disease driver.

Recent evidence demonstrates that the TRPC5-Rac1 pathway, a critical regulator of cellular motility, forms a vicious cycle that drives pathogenic remodeling of the actin cytoskeleton in podocytes.  The cause of FSGS is the result of podocyte dysfunction and injury, a result of dysregulation of the podocyte cytoskeleton. Many familial and sporadic forms of FSGS have been linked to genetic or environmental dysregulation of Rac1 signaling within the podocyte, highlighting the importance of Rac1 as a driver of kidney disease.

Activation of the TRPC5-Rac1 pathway causes podocyte loss and breach of the filtration barrier, leading to proteinuria, the hallmark of FSGS.  Inhibition of TRPC5 and subsequent suppression of Rac1 signaling offers a potential point of therapeutic intervention to restore podocyte integrity and halt disease progression.

We believe approximately 60-70% of people with FSGS have disease due to activation of the TRPC5-Rac1 pathway leading to podocyte injury, podocyte loss, and kidney failure.

How is FSGS Diagnosed?

FSGS is diagnosed by a renal biopsy, but research is being conducted to discover novel biomarkers that may allow for non-invasive ways to diagnose and treat FSGS.

Key Stats about FSGS

40%

Of adult nephrotic syndrome cases are caused by FSGS

20%

Of pediatric nephrotic syndrome cases are caused by FSGS

FSGS affects 100K people in the US and EU
5-10yrs

Average timeframe after within which people typically progress to ESKD

2k

Number of people who progress to ESKD annually in U.S.

60%

Of patients experience recurrence of FSGS after first kidney transplant

80%

Of people with FSGS experience recurrence in subsequent transplants if they lost their first

How is FSGS treated?

There are no approved treatments for FSGS. The current treatment includes steroids and renin angiotensin system inhibitor drugs (ACE inhibitors or ARBs) to control blood pressure and reduce proteinuria. Other medications may be used to suppress the immune system. Once a person progresses to ESKD, the only treatment options are dialysis and transplantation.

Living with FSGS

February 2021

In this video, Jill H. talks about living with and managing FSGS, including her experience with dialysis and kidney transplants.

Watch a more in-depth interview with Jill for “The Feeder”, Goldfinch Bio’s interview series.