Led by researchers at Beth Israel Deaconess Medical Center (BIDMC), the findings are described in the Proceedings of the National Academy of Sciences (PNAS), which appears on-line the week of April 24, 2006.
Symptoms of Alport syndrome, the second most common genetic cause of kidney failure, usually appear in children, affecting the kidneys' filtration system and typically leading to end-stage renal disease in the patient's teens, 20s or 30s. The disease additionally causes deafness in some patients.
"This is one of 31 human diseases that occur because of genetic defects in the body's extracellular matrix and basement membrane proteins, " explains the study's senior author Raghu Kalluri, PhD, chief of the division of matrix biology at BIDMC and associate professor of medicine at Harvard Medical School.
Present throughout the body, the extracellular matrix (ECM) is made of collagens, proteogylcans, noncollagenous glycoproteins and in some tissues, elastin fibers. The ECM serves a unique role by constructing a "scaffold" for cells, thereby maintaining the structural integrity of many tissues.
"In normal kidneys, a specialized form of extracellular matrix known as the glomerular basement membrane [GBM], composed primarily of type IV collagen, is the key component of the blood filtration apparatus," says Kalluri.
However, in patients with Alport syndrome, mutations in three different type IV collagen genes cause structural damage to the GBM, leading to a breakdown of the organ's filtration system, and resulting in the seepage of blood and protein into the urine and eventual kidney failure.<
Source:Beth Israel Deaconess Medical Center