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What is Alport Syndrome?
Alport syndrome is a rare health condition that causes kidney disease and impacts hearing and sight.
Unfortunately, while rare, this genetic syndrome is passed through families. Alport syndrome occurs due to mutations in the COL4A3, COL4A4, and COL4A5 genes.
What's in this Guide?
- What is Alport Syndrome?
- Genetic Types of Alport Syndrome
- Causes of Alport Syndrome
- Inheritance Pattern of Alport Syndrome
- Alport syndrome is inherited in three different ways, and for that reason, it has three different types:
- Signs & Symptoms of Alport Syndrome
- Risk Factors for Alport Syndrome?
- Diagnosis of Alport Syndrome
- Treatment Options for Alport Syndrome
- Prognosis for Alport Syndrome
- What To Do Next
Disclaimer: Before You Read
It is important to know that your genes are not your destiny. There are various environmental and genetic factors working together to shape you. No matter your genetic makeup, maintain ideal blood pressure and glucose levels, avoid harmful alcohol intake, exercise regularly, get regular sleep. And for goodness sake, don't smoke.
Genetics is a quickly changing topic. Read More...
Alport syndrome causes health problems because it damages blood vessels and glomeruli (the filters) in the kidneys.
This damage creates a buildup of scar tissue, which makes it difficult for the kidneys to properly filter blood and remove toxins and nutrient buildup.
This damaging process, called fibrosis, usually leads to some form of kidney disease and will eventually cause kidney failure — in fact, almost all cases of Alport syndrome (90% according to the Alport Syndrome Foundation) lead to end-stage renal disease (ESRD) for men with certain variations of the genetic disorder.
It is not unusual for people with Alport syndrome to seek out transplants at some point in life to replace damaged or non-functioning kidneys.
Alport syndrome also leads to degeneration of the inner ear and eyes.
In many cases, people with Alport syndrome can hear the first years after birth and throughout their childhood, though by early adolescence have some level of hearing loss.
While hearing loss is a common side effect of Alport disease, not all people who have it will lose their hearing altogether, or early on in life.
In fact, hearing loss is often less severe in women and frequently occurs later in life.
Many people with Alport syndrome will have eye abnormalities, often related to the shape of the eye or with abnormal eye pigment.
Some people with the disease suffer from corneal erosion, which can cause pain and itching, as well as loss of vision from a macular hole — a condition caused by thinning of the retina that can lead to distorted, unclear vision.
There are three kinds of Alport syndrome, and the severity of the disease and its effects is often based on which variant a person has.
Gender also seems to play a role, with men often having more severe side effects than women.
How rare is Alport Syndrome?
Alport syndrome is relatively rare. According to the National Institutes of Health, Alport syndrome prevalence is relatively low, with the disease being diagnosed in 1 out of 50,000 newborn babies.
According to the Alport Syndrome Foundation, researchers estimate that between 30,000 and 60,000 people in the U.S. are living with Alport syndrome at any given time.
But because it is a genetic-linked disease, meaning that it runs in families and is passed from parent to child, it can seem less rare for families with multiple diagnoses.
Alport syndrome appears in both men and women, though men often have more intense symptoms and disease progression.
Genetic Types of Alport Syndrome
Researchers have determined that there are three different kinds of Alport syndrome. Each type of the disease has different impacts on a person’s body.
In addition, the three forms are genetically inherited in slightly different ways. The forms of Alport syndrome include:
- X-linked Alport syndrome: This form of Alport syndrome is the most common, and according to the National Kidney Foundation, 80% of people with the disease have this form. What sets this type of Alport syndrome apart is that it is passed through the X chromosome.
- Autosomal recessive Alport syndrome (ARAS): This type of the disease occurs when both parents have a mutation in the COL4A3 or COL4A4 gene.
- Autosomal dominant Alport syndrome (ADAS): The third type of Alport syndrome is inherited when only one parent has the disease and passes that genetic mutation along. This form is the rarest of all three kinds.
Gender-based differences in Alport Syndrome
Researchers and physicians often report that Alport syndrome is less devastating in women than it is in men, though you should know that the severity of each case varies from person to person.
Alport syndrome in males is usually characterized by more severe and rapidly progressing symptoms.
Men with the disease often have hearing loss at an earlier age — with the Alport syndrome age of onset starting as young as 10 years old.
By 15 years old, many teenage boys with the disease have heightened blood pressure attributed to the condition.
In men, kidney function often begins to decline by their early 20s, leading to chronic renal failure by their mid-20s.
When it comes to X-linked Alport syndrome, the disease is worse in men; according to the National Kidney Foundation, “without treatment, 90% of males develop kidney failure by 40 years old.”
On the other hand, Alport syndrome in females is often a slower-moving condition. Women who have X-linked Alport syndrome have kidney failure much less than men, and when they do, the disease progresses more slowly.
According to Kidney Research UK, it’s not uncommon for women to live with undiagnosed Alport syndrome until having a male child who inherits the disease. Overall, women often have less hearing loss than men with X-linked Alport syndrome.
Causes of Alport Syndrome
Alport syndrome isn’t contagious and can’t be transmitted to healthy people because it is an inherited disease. It occurs when changes to the COL4A3, COL4A4, or COL4A5 gene are passed from parent to child.
These genes are responsible for the production of type IV collagen, an essential protein in the body that helps the kidneys filter blood to remove toxins and nutrient buildup.
The gene mutations create abnormalities in collagen, which leads to the development of abnormal glomeruli — the blood vessels responsible for kidney filtering.
When the glomeruli are damaged, scar tissue is created in the kidney, which makes it harder for the glomeruli to function properly.
Because Type IV collagen is also used by the body within the ears, Alport syndrome can also greatly impact a person’s hearing.
Inside the inner ear, this kind of collagen helps “transform sound waves into nerve impulses for the brain,” according to the National Institutes of Health.
A lack of Type IV collagen in this area of the body can make it difficult for the inner ear to do this task, eventually leading to permanent hearing loss.
Type IV collagen is also important for eye health; in fact, collagen is necessary for helping the eye keep its proper shape and retina color.
Whenever the eyes are deprived of collagen, a variety of abnormalities can happen.
Inheritance Pattern of Alport Syndrome
Alport syndrome is inherited in three different ways, and for that reason, it has three different types:
X-linked Alport syndrome, autosomal recessive Alport syndrome (ARAS), and autosomal dominant Alport syndrome (ADAS).
How the disease is inherited also depends on gender.
In general, here is how X-linked Alport syndrome — the most common form of the disease — is passed from parent to child for both men and women:
- Men have one X and one Y chromosome. In men with X-linked Alport syndrome, the mutated gene is passed from parent to child through the X chromosome. Since men only have one X chromosome, the Y chromosome isn’t able to compensate for the defect, meaning that the man will inherit Alport Syndrome.
- Women have two X chromosomes, which means that if one of the X chromosomes they inherit has a mutation, the second X is able to compensate for the defect. In many cases, this drastically reduces the impact of Alport syndrome to the point that a woman may not even know she has the disease.
One important thing to know about inheriting X-linked Alport syndrome is that the mutation cannot be passed from father to son, meaning men diagnosed with this kind of the disease inherit it from their mothers.
So, does this make Alport syndrome a dominant or recessive gene mutation? Generally, the disease can be passed both ways.
That’s where the less common ARAS and ADAS forms come in:
- With autosomal recessive Alport syndrome (ARAS), the disease is inherited because both parents have gene mutations. As carriers, both parents pass along the mutation. This form of Alport syndrome is diagnosed in 15% of all cases.
- With autosomal dominant inheritance (ADAS), one parent who has the disease passes along the gene mutation to their child. It is unclear why exactly this happens, though it is rarer — only about 5% of Alport syndrome cases have this diagnosis.
Signs & Symptoms of Alport Syndrome
It’s not uncommon for people with Alport syndrome to have delayed signs and symptoms that seemingly appear out of nowhere — often around age 10 for boys and much later, if at all, for girls. Common symptoms of Alport syndrome include:
- Blood in the urine (also called hematuria)
- A buildup of protein in the urine (also called proteinuria)
- High blood pressure (also called hypertension), especially at a young age
- Swelling in the face around the eyes as well as in the lower extremities
- Joint pain
- Hearing loss
- Difficulty seeing clearly
Alport syndrome eye symptoms are very specific to the disease. One symptom, anterior lenticonus, changes the shape of the eye, while other symptoms include dot-and-fleck retinopathy (abnormal retina coloring).
Risk Factors for Alport Syndrome?
Alport syndrome is relatively rare, though some people are more at risk for developing the disease than others.
Men are more likely to suffer from severe effects of Alport syndrome, although the disease appears in both genders.
Who does Alport syndrome typically affect?
Alport syndrome typically runs in families and affects both men and women. You should consider getting tested for Alport syndrome if:
- Someone in your family, especially a parent or sibling, has been diagnosed with the condition
- Multiple people in your family have had kidney illnesses or failure
- Your eye doctor discovers collagen-related abnormalities during an eye appointment
- You experience symptoms such as hearing loss and high blood pressure at an unusually young age
Diagnosis of Alport Syndrome
Because Alport syndrome has very specific symptoms and indicators, doctors have an easier time determining if you have the condition.
Plus, the benefit of genetic testing can also verify a diagnosis. The Alport syndrome age of diagnosis ranges between genders, with many males diagnosed during childhood or their early teenage years.
Many women are diagnosed later in life — often during their childbearing years if they are asymptomatic and end up having a child who has inherited the disease — though women with severe cases of Alport syndrome may be diagnosed earlier than that.
How is Alport Syndrome diagnosed?
Doctors can use some or all of the following tests when it comes to making an Alport syndrome diagnosis:
- Blood tests to identify if there are high levels of proteins in the blood
- Urine tests to look for protein and blood
- Hearing and vision testing to see if there has been hearing or vision loss
- Glomerular filtration rate (GFR) test, which analyzes how well the kidneys are functioning
- Kidney biopsy for an in-depth look to determine if there is scar tissue buildup caused by a lack of Type IV collagen
- DNA testing
Is genetic testing available?
Genetic testing is a large component of making an Alport syndrome diagnosis.
In fact, having a genetic test performed allows your physician to confirm other tests for a solid diagnosis.
For women who have Alport syndrome but don’t show symptoms, genetic testing is the only way to confirm that they carry the condition.
Other testing available
Some doctors find that other tests can also help with making a diagnosis. In some instances, close family members are asked to take urine or blood tests to determine if there is a family history of Alport syndrome.
In other situations, doctors may choose to use skin biopsies to determine if someone has X-linked Alport syndrome.
That’s because Type IV collagen exists in the skin, and a skin biopsy can show if the protein exists at the proper levels.
Testing during pregnancy
If you are pregnant and are concerned about passing along Alport syndrome to a child, know that it is possible to test for the disease during pregnancy.
Your doctor can perform an amniocentesis (a procedure that collects amniotic fluid) combined with genetic testing.
In addition, it’s also possible to collect your baby’s DNA through chorionic villi sampling (CVS).
Treatment Options for Alport Syndrome
When it comes to treating Alport syndrome, it is important to ensure the kidneys are functioning as well as possible. Treatments for the condition include:
- ACE inhibitors to lower high blood pressure and reduce the amount of protein in the kidneys
- Diuretics and water pills to help flush toxins and proteins from the body
- Kidney transplant
- Following an Alport syndrome diet that is low in salt and potassium but high in lean protein
Alport syndrome kidney transplants often occur after a patient’s kidneys have failed, though researchers have found that many people with the disease who have a transplant have an increased quality of life and fewer effects of the condition.
Is Alport Syndrome curable?
Unfortunately, there is no cure for Alport syndrome. But, more and more research into the disease has provided new medications and procedures that may help increase a person’s lifespan and quality of living.
Prognosis for Alport Syndrome
One of the biggest concerns about Alport syndrome is how quickly it degrades the kidneys and causes them to shut down.
For many men with the disease, their kidneys often become low or non-functioning by age 40, meaning they have kidney failure.
Still, newer medications that reduce the effects of Alport syndrome, in combination with kidney transplants, have brightened the outlook for Alport syndrome.
With these tools, a person who has the disease can live a normal life, though it’s important to know that without treatment and careful attention, a person’s lifespan can be shortened due to kidney failure.
Is Alport Syndrome fatal?
If untreated, Alport syndrome can be fatal because the kidneys will stop filtering a person’s blood and shut down.
Also known as end-stage renal failure, this form of organ failure can lead to death.
Still, there are many ways to prevent or delay organ failure, such as dialysis or a kidney transplant.
In fact, with medication and the correct medical therapies, Alport syndrome life expectancy is similar to a person without the disease.
What To Do Next
If you haven’t been tested for Alport syndrome, but believe you may have the disease, it’s important to speak with your doctor about testing, because the longer Alport syndrome goes untreated, the more damage it can do to your body.
Being diagnosed and living with Alport syndrome can be scary, but you should know that many people live with the disease thanks to the assistance of medication, a modified Alport syndrome diet, and kidney transplants, if necessary.
Learning more about Alport syndrome and disease research can give you a better understanding of the disease.
And while there’s no way to prevent Alport syndrome, working with a genetic counselor to understand how you can pass it on to future children — or may have passed it along to your kids — is a strong tool for families.
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