Alport syndrome is a rare hereditary condition characterized by a range of symptoms, the most important of which are blood and protein in the urine and hypertension (high blood pressure). The condition was first identified in a British family in 1927 by British physician Cecil A. Alport. Alport syndrome causes progressive kidney damage, often requiring dialysis or a kidney transplant at a young age. There are three genetic types of Alport syndrome, which vary in the severity of symptoms and age of onset.
- What is Alport Syndrome?
- Epidemiology syndrome
- Causes and heredity of the condition
- Symptoms: Kidneys (renal failure), urine (hematuria), blood pressure, ears (hearing loss), eyes
- Diagnosis and examinations
- Therapy
- Prognosis syndrome
What is Alport Syndrome?
Alport syndrome is an inherited kidney disease that also affects the inner ear (cochlea) and the eyes. The cause is a genetic mutation on type IV collagen, a protein. Type IV collagen, a type of connective tissue, is essential in forming important tissue structures such as basement membranes found in all tissues including the kidney, inner ear and eye.
Alport syndrome causes progressive kidney damage. The glomeruli (capillaries in the kidney) and other normal kidney structures such as tubules are gradually replaced by scar tissue, leading to renal failure (decreased or absent kidney function). All boys with Alport syndrome, regardless of genetic type, eventually develop kidney failure. These boys often need dialysis or a kidney transplant during their teenage years or early adulthood, although kidney failure can occur later in some people (40-50 years). Most girls with the X-linked form of Alport syndrome do not develop kidney failure. In women with the more severe form of Alport syndrome, pregnancy can accelerate the progression of kidney failure. Nephrocalcinosis (deposits of calcium in kidneys) is another possible feature of the disease.
Epidemiology syndrome
Reliable scientifically based information on the prevalence of Alport syndrome in Europe is nowhere to be found. That is why only figures from the United States are included in this article.
Alport syndrome is a rare disease that affects fewer than 200,000 people in the United States. The incidence of Alport syndrome is estimated at approximately 1 in 5000-10,000 people in the United States, leaving approximately 30,000 to 60,000 people in the United States with the condition. Alport syndrome is estimated to account for 3% of children with chronic kidney disease and 0.2% of adults with end-stage renal disease in the United States.
Causes and heredity of the condition
There are three genetic types of Alport syndrome:
- X-linked Alport syndrome (XLAS): This is the most common form (85%) due to mutations in the COL4A5 gene. Affected males usually have more severe disease symptoms than affected females.
- Autosomal recessive Alport syndrome (ARAS): This occurs in approximately 10% of patients. The severity of the disease is the same in affected men and women.
- Autosomal dominant form of Alport syndrome (ADAS): This occurs in approximately 5% of patients. The severity of the disease is also the same in affected men and women.
Symptoms: Kidneys (renal failure), urine (hematuria), blood pressure, ears (hearing loss), eyes
Kidneys
Alport syndrome always affects the kidneys . The ever-present symptom of the disease is blood in the urine (medical term: hematuria). Boys with X-linked Alport syndrome develop hematuria in childhood. The vast majority of girls with X-linked Alport syndrome also have hematuria, but this is more likely to be recurrent (come and go). The hematuria of Alport syndrome is usually microscopic, meaning it can only be detected with a microscope or through a urine sample. Sometimes the urine of children with Alport syndrome is brown, pink, or red (gross hematuria) for several days when they have a cold (mild infection with nose and throat symptoms) or flu. This type of hematuria resolves spontaneously and is not harmful, although it can be frightening.
Urine and blood pressure
As boys with Alport syndrome grow older, they begin to show other symptoms of kidney disease including protein in the urine and increased blood pressure . These symptoms are often present in the teenage years. Girls with Alport syndrome usually have no protein in their urine and only develop high blood pressure later in life. Nevertheless, symptoms also appear in the teenage years of girls with Alport syndrome.
Ears and ears
Many people with Alport syndrome also have hearing problems and eye abnormalities , because the type IV collagen proteins are important for the normal structure and function of the inner ear and eye.
Other symptoms
A whole range of symptoms are also possible; However, they should not all be present at the same time. These symptoms may be different depending on age, gender and the genetic type of Alport syndrome.
- Hematuria: Blood in the urine, the most common and earliest symptom of Alport syndrome.
- Hypertension: High blood pressure: Usually seen later in life.
- Eyes: About 15% of men with Alport syndrome have a lens shape abnormality called lenticonus anterior. There is a kind of cone-shaped protrusion at the front of the lens. When the lens is damaged, cataracts and associated vision problems are possible. These vision problems are more common in men than in women.
- Ears: Progressive hearing loss is another major symptom of Alport syndrome. About 80% of boys with Alport syndrome develop progressive hearing loss, often in their teenage years. Usually both ears are progressively affected. Hearing aids are usually very effective in these patients. Girls with Alport syndrome sometimes also have progressive hearing loss, but less often than boys, and usually only at a later age. Progressive hearing loss cannot be improved with a kidney transplant.
- Proteinuria: Proteinuria involves excessive amounts of protein in the urine.
- swelling of the legs, swelling of the ankles and feet and swelling around the eyes.
Diagnosis and examinations
The diagnosis is confirmed by a number of examinations:
- Audiometry: Children with a family history of Alport syndrome should undergo audiometry (hearing examination) to diagnose the condition, as well as for regular check-ups.
- Biopsy: Examination of kidney and skin tissue for structural abnormalities. A kidney biopsy usually provides the diagnosis if this was not previously determined by a skin biopsy.
- Genetic research: The genetic type of Alport syndrome can also be determined in this way.
- Laboratory tests: A urinalysis reveals hematuria and proteinuria; blood tests show the degree of renal insufficiency.
- Renal ultrasound: In the early stages of Alport syndrome, an ultrasound shows healthy kidneys of normal size, but in renal failure the kidneys shrink symmetrically and gradually.
- Eye examination : This is important for the early detection and monitoring of the lens abnormality, as well as to detect macular surfaces and other eye lesions.
Therapy
There is no proven effective treatment available for Alport syndrome. So doctors also administer the treatments they give to patients with high blood pressure and other symptoms of kidney disease. Kidney transplantation is usually very successful in people with Alport syndrome, and is the best treatment for kidney failure. Angiotensin receptor inhibitors, angiotensin-converting enzyme (ACE inhibitors), and cyclosporine are also sometimes given to patients with Alport syndrome to improve proteinuria and elevated blood pressure. They could also slow the progression of kidney failure, but this requires further research. The current studies that have already been completed are rather small and uncontrolled. Sometimes the surgeon surgically removes the eye lens and replaces it with an artificial lens.
Prognosis syndrome
The renal prognosis for both male and female patients with autosomal recessive disease is poor; most develop kidney failure.
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