
Alport syndrome (also known as hereditary nephritis) is a genetic disorder that primarily results in problems with hearing, the eye and the kidney.
Alport syndrome is responsible for approximately 3% of children who have kidney failure and 0.2% of adults with kidney failure.
Both males and females can be affected by Alport syndrome; however, boys tend to have more serious complications. Males are more affected by this disorder than females because the gene that causes Alport syndrome is located on the X-chromosome and therefore has X-linked inheritance. Females have two X-chromosomes, so if a female receives one X-chromosome with a genetic change (mutation), this change is somewhat balanced by the fully functioning gene on the other X-chromosome. Males only have one X-chromosome and one copy of the gene that causes this disorder.
Most children with this disorder inherit the gene from a parent, but new genetic changes can occur and the child may be the first one in the family to be affected. Some forms of Alport syndrome may also be caused by genetic changes in other genes on other chromosomes.
The hearing and vision problems may not be present in young children, but many children, more specifically male children, with Alport syndrome will have small amounts of blood in their urine (hematuria) when they are young.
The signs and symptoms of Alport syndrome in addition to the blood in the urine include:
1. Deafness, most often to high pitched tones,
2. Protein in the urine (proteinuria),
3. High blood pressure, and
4. Eye problems such as cataracts (cloudy lenses), worsening vision, or nystagmus (rapid back-and-forth movements of the eyes).
More rarely, those with Alport syndrome may have some difficulty with swallowing, cough, or bronchitis.
Alport syndrome occurs because collagen, one of the major proteins responsible for forming connective tissue in the body, is not formed properly as the result of an abnormal gene. The abnormal collagen is found in the filtering part of the kidney (glomerulus) which causes the normal filtering barrier to become "leaky." As the kidney becomes less able to control filtration, kidney failure develops. The collagen is also found in the eyes and ears which explains why these different organs may be affected
Alport syndrome may be suspected in a child who has a family with a history of kidney problems and deafness. Since young children may have blood in their urine before any of the other symptoms develop, this may be one of the first signs of the disease. Therefore, checking urine for blood and/or protein may be the first hint at the diagnosis. A kidney biopsy may be the next step in order to diagnosis Alport syndrome since the other symptoms of hearing loss and vision problems may not yet be present. The kidney biopsy consists of placing a needle through the skin on the back and into the kidney to take a small sample to check under the microscope for abnormal collagen.
There is currently no cure for Alport syndrome, so the treatment is directed at controlling the damage to the kidney with medications, controlling high blood pressure, and assisting the children with any hearing loss or eye problems. If the kidney problems worsen and the child's kidney stop working normally, he or she may need to start dialysis which performs the job of the kidney by cleaning and filtering the blood. Some children may be eligible for kidney transplants once their kidneys are no longer functioning normally.
The hearing loss and kidney failure associated with Alport syndrome usually progresses over time. Kidney failure usually occurs between the ages of 16 and 35 years. Dialysis and kidney transplant have begun allowing people with Alport syndrome to live longer.
As mentioned previously, girls tend to have fewer symptoms than boys, and they may never even realize that they have hearing loss. Females may only find out they have Alport syndrome once they have a son with the disease.
Kidney Foundation of Canada Website
http://www.kidney.ca/page.asp?intNodeID=22140
Very comprehensive explanation of Alport Syndrome. The site also provides links to research updates and peer support.
Medline Plus
http://www.nlm.nih.gov/medlineplus/ency/article/000504.htm
A website from the National Institute of Health which describes Alport syndrome.
National Kidney Foundation Website
http://www.kidney.org/ATOZ/atozItem.cfm?id=47
A thorough review of Alport syndrome and some general information about how kidneys work and dialysis.
Kashtan CE (2007). "Hereditary nephritis (Alport syndrome)." UpToDate. Online http://www.uptodate.com/. Accessed March 22, 2007.
The Kidney Foundation of Canada. "Alport Syndrome." http://www.kidney.ca/page.asp?intNodeID=22140. Accessed March 22, 2007.
Saxena, R. "Alport Syndrome." eMedicine. Online http://www.emedicine.com/med/topic110.htm. Accessed March 22, 2007.
