Clinical Features of Alport Syndrome
People with Alport syndrome always have kidney involvement. Many people with the disease also have deafness and abnormalities of the eyes, because the type IV collagen proteins are important to the normal structure and function of the cochlea and the eye.
The hallmark of Alport syndrome is blood in the urine (hematuria). In boys with X-linked Alport syndrome hematuria first appears in early childhood, and their urine is always positive for blood. Over 90% of girls with X-linked Alport syndrome have hematuria, but it may be intermittent. Some girls who carry a mutation in the alpha-5 chain gene do not have blood in their urine.
All boys and girls with autosomal recessive Alport syndrome have hematuria. Most people who carry a mutation in one copy of the alpha-3 or alpha-4 chain genes have hematuria, but some do not.
The hematuria of Alport syndrome is usually microscopic, meaning it can only be detected with a microscope or a urine dipstick. Sometimes children with Alport syndrome have brown, pink or red urine (gross hematuria) for several days, associated with a cold or the flu. This gross hematuria eventually stops on its own. It can be frightening, but it is not harmful.
As boys with Alport syndrome get older, they begin to show additional signs of kidney disease, such as protein in the urine (proteinuria) and high blood pressure. These symptoms are often present by the time the boys are teen-agers. Girls with Alport syndrome usually do not have protein in the urine and high blood pressure until much later in life, but occasionally these symptoms appear in childhood or adolescence.
Deafness is an important feature of Alport syndrome. About 80% of boys with the disease will develop deafness at some point in their lives, often by adolescence. Fortunately, hearing aids are usually very effective in boys with deafness caused by Alport syndrome. Girls with the disease may also develop deafness, but less frequently than boys, and usually later in life. The deafness of Alport syndrome is not improved by kidney transplantation.
About 15% of men with Alport syndrome have an abnormality in the shape of the lens called anterior lenticonus, which may cause problems with vision and lead to cataract formation. Some people with Alport syndrome have abnormal pigmentation of the retina, but this does not result in any abnormalities of vision. Recurrent corneal erosion is a painful eye problem that can occur in people with Alport syndrome.