Dense deposit disease (DDD), also known as membranoproliferative glomerulonephritis type II or MPGN II, is a rare autoimmune disease that affects both the kidneys and the eyes. DDD primarily damages the glomeruli in the kidneys, where proteins of the immune system form dense deposits on the glomerular basement membrane. Over time, these deposits hinder the kidneys’ ability to filter fluids and waste from the blood. Approximately half of those affected will develop kidney failure within a decade of diagnosis, and 85% will face kidney failure within two decades. In addition to kidney issues, individuals with DDD may develop whitish-yellow deposits, called drusen, in the retina of the eye.
DDD is typically diagnosed in children and teenagers between the ages of 5 and 15. This condition is exceedingly rare, affecting only two or three people per million.
DDD is an autoimmune disorder that occurs when the immune system no longer distinguishes between foreign invaders and the body’s own cells, resulting in attacks on the body’s organs and tissues. Some individuals with DDD have gene mutations in the complement factor H (CFH) gene, which produces the complement factor H protein responsible for regulating part of the immune system. These gene mutations lead to a defective protein and an overactive immune system that attacks the kidneys. However, not everyone with gene mutations develops DDD. Other factors like medications, chronic diseases, infections, cancers, and pregnancy may also contribute to DDD.
Early symptoms of DDD resemble kidney disease and include protein in the urine (proteinuria), resulting in foamy urine, and pink-tinged or red urine due to blood (hematuria). As kidney disease progresses, symptoms become more apparent and may include:
DDD is diagnosed through a kidney biopsy, where a small amount of kidney tissue is examined under an electron microscope to identify dense deposits. Blood tests for nephritic factors, autoantibodies that interfere with the immune system, can also be performed.
As kidney disease progresses to kidney failure, it affects all major organs, leading to complications like heart disease, bone disease, gastrointestinal issues, nervous system problems (e.g., peripheral neuropathy and restless leg syndrome), dry skin, itching, anemia, high blood pressure, and weakened immunity. Drusen deposits in the eyes can cause colorblindness, night vision problems, and vision loss.
While DDD is not curable, treatments are available to slow kidney disease progression and manage kidney failure. Treatment approaches include:
Currently, there is no specific treatment for drusen, but therapies used in age-related macular degeneration (AMD) may offer some help. Individuals with DDD should regularly consult an ophthalmologist for eye care.
Ongoing research into the causes and treatment of DDD focuses on factors like the defective complement factor H protein, the development of specific immunotherapies, restoring factor H production through bone marrow transplantation, and more.
Although DDD is a rare autoimmune disorder, organizations like Kidneeds are raising awareness to support those living with it. Typically diagnosed in childhood, DDD affects both the kidneys and, often, the eyes. While there is no cure for DDD, available treatments can help slow the progression of kidney disease.
