(Source: Boystown Research Registry)
Alport Syndrome (AS) is characterized by hereditary nephritis (kidney disease known as Bright´s disease in the past) and sensorineural hearing loss. The mode of inheritance may be X-linked or autosomal dominant. Less common symptoms include a defect of the lens of the eye called anterior lenticonus and a defect of blood platelets that can cause bleeding complications. AS is usually diagnosed by a test for blood and protein in the urine, hearing tests, and an extended family history.
AS does not seem to be associated with any racial or geographic group. Males are affected more severely than females; this is true whether the mode of inheritance is autosomal or X-linked dominant. The most consistent sign of kidney involvement is hematuria which is red blood cells in the urine. Hematuria which causes an actual change in the color of the urine, generally occurs only at times of infection and fever. Microscopic hematuria which is detected only in the laboratory may be present from birth, and may be the only sign of kidney involvement in females. Progression to end-stage-renal-disease (ESRD), the point at which dialysis or kidney transplant is necessary, is gradual in males and unlikely in females. There are both juvenile and adult types of AS; ESRD occurs in childhood or adolescence in the juvenile type and during middle age in the adult type. In this country, AS accounts for 3% of the ESRD and is the reason for 1-2% of kidney transplants. Medical management of the kidney disease includes a low protein diet, control of high blood pressure, and eventual dialysis or transplant.
Hearing loss commonly occurs in childhood.
Most subtypes of AS include a bilateral progressive sensorineural hearing loss of mild to moderate degree, but some individuals may have a severe to profound loss. Females generally have a milder hearing loss than their male relatives if they have one at all. Management of the hearing loss includes regular audiologic follow-up, use of hearing aides, and avoidance of certain drugs and excessive noise exposure that can cause further hearing loss.
Mutations (changes from the normal genetic structure) responsible for AS have been found in a collagen gene, COL4A5, which is on the long arm of the X chromosome (Xq22). Several different mutations in the COL4A5 gene have been identified, which are thought to relate to the variation in age of onset and severity among families with AS. At this time a gene for autosomal dominant AS has not been identified.
The information presented here first appeared in publications of the Boys Town National Research Register for Hereditary Hearing Loss, the National Institute on Deafness and Other Communication Disorders (NIDCD), Hereditary Hearing Impairment Resource Registry (HHIRR), or the Boys Town Research Registry for Hereditary Hearing Loss.
The Boys Town Research Registry for Hereditary Hearing Loss
The Boys Town Research Registry for Hereditary Hearing Loss (Registry) is designed to foster a partnership between families, clinicians and researchers in the area of hereditary hearing loss/deafness through three primary functions. First, the Registry disseminates information to professionals and families about clinical and research issues related to hereditary deafness/hearing loss. Second, the Registry collects information from individuals interested in supporting and participating in research projects. This information is used to support the third function of the Registry - matching families with collaborating research projects.
For more information, contact:
Research Registry for Hereditary Hearing Loss
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