C3 Glomerulopathy (C3G) is a rare disease caused by a fault in the complement system. Complement is part of your body’s normal immune response to bugs.
Your body has an in-built system of protector proteins that stop complement from attacking your own cells. In C3G this system fails.
This causes complement – primarily the complement protein C3 – to be deposited in a part of the kidney called the glomerular basement membrane.
This leads to holes developing in the membrane and large protein molecules that are normally not excreted are able to leak out into the urine – this is known as proteinuria.
Over time this proteinuria will damage the kidney and may lead to end stage kidney disease.
What are MPGN, C3GN, DDD?
Membrano-Proliferative Glomerulonephritis (MPGN) refers to a group of diseases based on how the kidney looks under a microscope. In MPGN the kidney is damaged by deposits of immune substances in the glomerular basement membrane.
These deposits can be immunoglobulins, complement or a mixture of both.
Where the deposits are predominantly complement and are thought to be caused by abnormal activity in the complement system this is known as C3 Glomerulopathy.
The terms C3 Glomerulonephritis (C3GN) and Dense Deposit Disease (DDD) are sub-groups of C3G and are distinguished by the way in which the complement deposits are seen on a biopsy.
– In C3GN the deposits tend to appear patchy.
– In DDD the deposits are seen more as long thick strips of complement.
Why does C3G happen?
Patients may develop autoantibodies to the complement proteins. These autoantibodies then attack the protein and stop it from doing its job.
There may also be a genetic fault in the complement system or the protector proteins that allows complement to be deposited in the kidney.
How does C3G present?
C3G does not normally present acutely, symptoms normally develop over a period of months.
– Patients may notice haematuria (blood in the urine.)
– A urinalysis or urine dipstick may be performed, often for an unrelated reason such as a routine medical examination, which shows microscopic haematuria or proteinuria (protein in the urine).
– Patients may also complain of fluid and swelling in their lower limbs.
– In many cases a problem is not identified until a blood test shows abnormal kidney function and the patient is referred to a kidney specialist.
What is C3 Glomerulopathy?
C3 Glomerulopathy (C3G) is a rare disease of the kidneys caused by a fault in the complement system.
Complement is part of your body’s normal immune response to bugs.
Your body has an in-built system of protector proteins that stop complement from attacking your own cells.
In C3G this system fails.
This causes complement – primarily the complement protein C3 – to be deposited in the filtering part of the kidney called the glomerulus
The damage to this part of the kidney can lead to abnormal kidney function and leaking of blood and protein into the urine.
Over time, this can lead to end-stage kidney disease.