Alport syndrome: An hereditary condition characterized by kidney disease, sensorineural (nerve) deafness and sometimes eye defects.
The classic disorder as described by Alport in 1927 is nephritis (inflammation of the kidney), often progressing to renal failure, and sensorineural (nerve) hearing loss affecting both sexes in successive generations. The kidney disease becomes evident as recurrent microscopic or gross hematuria (blood in the urine) as early as childhood, and usually earlier in males than in females. Progression to renal failure is gradual and usually occurs in males by the fifth decade.
The sensorineural (nerve) hearing loss in Alport syndrome primarily affects high tones and occurs in 30 to 50% of relatives with renal disease. The severity of the auditory and renal features do not correlate in a given individual with Alport syndrome.
Alport syndrome is not one disease. It has diverse genetic causes; there are X-linked and autosomal dominant and recessive forms of Alport syndrome. There are also diverse clinical types of Alport syndrome including, for example, juvenile-onset Alport syndrome with deafness, adult-onset Alport syndrome with deafness, and adult Alport syndrome without deafness.
The X-linked disorder that has come to be known as Alport syndrome is characterized by hematuria (blood in the urine), progressive renal failure, and sensorineural (nerve) hearing loss and is frequently associated with both eye abnormalities (such as lens and retinal anomalies) as well as the identification of mutations in the gene encoding what is called the basement membrane specific type IV collagen alpha-5 chain (COL4A5), an X-linked gene. This syndrome was proven to be an X-linked dominant disorder.