Berger's disease, also called IgA nephropathy, is the most common form of glomerular kidney disease in the developed world. It is often mistaken for kidney stones or urinary tract infection. The primary symptom is blood in the urine, often accompanied by fever, pain, and/or protein in the urine.
For some patients, mostly children, it clears up by itself. For others, it progresses to end stage renal disease requiring dialysis or transplant.
There is a strong genetic component to Berger's disease, and familial forms are more common in northern Italy and eastern Kentucky. However, environmental factors are believed to be very important also.
IgA is an immunoglobulin that is part of the normal immune system. In Berger's disease, abnormal forms of IgA may be present in the blood. It is a major research challenge to understand why these abnormal IgA molecules develop. By some estimates, 10% of the general population has IgA deposits in the kidneys, but only 1 out of 50 people with IgA deposits develops Berger's disease. A renal biopsy is the standard diagnostic procedure.
Berger's disease progresses slowly in most cases. However, there is a large variation in outcomes for different patients. About half develop end stage renal disease within 25 years. The major risk factors for development of kidney failure from Berger's disease are:
1. Protein in the urine (>500 mg/day) for more than 6 months
2. Elevated creatinine in the blood
3. Blood in the urine (even at microscopic levels) for more than 6 months
4. High blood pressure that is poorly controlled
5. Extensive glomerulosclerosis or interstitial fibrosis or both on renal biopsy.
These risk factors explain less than half of the variation in outcomes. For many patients, blood pressure control is sufficient to prevent Berger's disease from progressing. For others, immune suppressive drugs may be needed.
A group in Italy has established a data bank of families with Berger's disease in order to identify the genes that contribute to the disease. The goal of this project is to discover the molecular pathway that causes kidney damage, and suggest targets for drug development.