Alport Syndrome (AS) is an inherited disorder of the basement membranes of the kidney, eye and ear. People who inherit defective genes for the "collagen" proteins in these basement membranes may develop progressive loss of renal function, deafness and abnormalities of the eye. In the kidneys, glomerular basement membranes normally act like filters, allowing fluid to move from blood vessels to urine while retaining protein and red blood cells within the bloodstream. Thus, one of the early signs of Alport syndrome may be leakage of small amounts of blood or protein into the urine during childhood.Collagen-containing membranes are also important for the shape of the lens of the eye and the structure of the inner ear.
Causes
Alport syndrome is an inherited form of kidney inflammation (nephritis). It's caused by a mutation in a gene for a protein in connective tissue, called collagen. The disorder is uncommon, and most often affects males. Women can transmit the gene for the disorder to their children, even if they have no symptoms.
When mutations prevent the formation of type IV collagen fibers, the basement membranes of the kidneys are not able to filter waste products from the blood and create urine normally, allowing blood and protein into the urine. The abnormalities of type IV collagen in kidney basement membranes cause gradual scarring of the kidneys, eventually leading to kidney failure in many people with the disease.
Approximately 50-80% of patients with X-linked Alport syndrome have mutations in the COL4A5 gene. Several hundred mutations, including missense mutations, splice-site mutations, and small deletions account for most cases of X-linked Alport syndrome. Few mutations have been found in more than 1 family.
Alport syndrome is a form of hereditary nephritis. There may be nerve deafness and congenital eye abnormalities associated with Alport syndrome. The cause is a mutation in a gene for collagen. The disorder is uncommon, and most often affects males since the genetic defect is typically found on the X chromosome.
Genes that Cause Renal Failure: Dialysis patients and their relatives with diabetes, high blood pressure and/or kidney failure are sought for a study at Case Western Reserve University to identify genes that contribute to or cause renal failure. Family participants will each receive $25 for their blood sample and complete medical and family histories.
Other common mutations lead to premature termination of protein translation and loss of the carboxy-terminal NC1 domain, resulting in defective interchain association and formation of the collagen network.
Symptoms
Hearing loss can be present at birth (congenital) or become evident later in life (acquired deafness). The distinction between acquired and congenital deafness specifies only the time that the deafness appears. It does not specify whether the cause of the deafness is genetic (inherited).
Treatment
There is no cure for Alport's syndrome, but treatment is available to ensure the kidneys can function as fully as possible. This includes limiting your intake of salts and fluids, high amounts of which put too much strain on the kidneys. Your doctor will also recommend that you take steps to control your blood pressure and potassium levels. If you have nephrotic syndrome, your doctor will recommend lowering your fluid intake; taking medications called diuretics, which help the kidneys eliminate wastes from the body by increasing urinatation; and eliminating all salts from your diet. You may also need to receive a transfusion of albumin.
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