What is it?
Alport syndrome (AS) is a rare genetic disorder of the glomerular basement membrane (part of the kidney’s filtration system). It is the second most common cause of inherited chronic kidney disease (CKD) after polycystic kidney disease. The condition can also cause hearing loss and may cause minor eye problems in some people.
Named after South African doctor Professor Arthur Cecil Alport, the condition is caused by genetic defects in the formation of a particular type of collagen fibre, collagen IV. This type of collagen is found in the kidneys, ears and eyes.
What are the causes
Around 85 per cent of cases of Alport syndrome are X-linked; they are caused by genetic mutations on the X chromosome. Males only have one X chromosome, so if they inherit an X chromosome with a mutation in the collagen IV gene on it, they get Alport syndrome. Females have two X chromosomes; if one of these has a mutation in the collagen IV gene, the affected person also gets Alport syndrome, but in a milder form. The mothers of people who have X-linked Alport syndrome usually have this milder form of Alport syndrome too, although sometimes the mutation only appears as the egg is being made.
The remaining 15 per cent of cases of Alport syndrome are caused by recessive inheritance, in which two different faulty genes for Collagen IV are inherited, one from each parent. In this type of Alport syndrome, females and males are equally badly affected. This type of Alport syndrome is more likely to occur in children whose parents are genetically related to each other (e.g. if they are cousins). The parents of children with autosomal recessive Alport syndrome don’t have any symptoms, but often have blood in their urine (haematuria) and a benign form of kidney disease called ‘Thin Basement Membrane Nephropathy’.
Symptoms
Kidneys
- Haematuria (blood in the urine) is present from birth. Haematuria is often invisible, and only detected by dipstick testing. Occasionally, minor infections can cause visible haematuria.
- Proteinuria (protein in the urine) may also develop. Occasionally, the proteinuria is so marked that nephrotic syndrome (a condition that can cause swelling due to fluid retention) is also diagnosed.
- Blood pressure generally starts to rise as the condition develops and, in men, kidney function begins to slowly decline.
Ears
People with Alport syndrome have normal hearing at birth and during early childhood, so their speech develops normally. Hearing difficulties in boys, and in women with recessive Alport syndrome, are usually first noticed at around ten years of age and a hearing test called an audiogram is likely to reveal mild to moderate high-tone deafness. During the next ten years, hearing loss is likely to slowly increase until, eventually, hearing aids may be prescribed.
In adult life, hearing loss tends to plateau and some useful hearing nearly always remains.
Eyes
Alport syndrome doesn’t normally affect the eyes in childhood but in adult life:
- The lens may slowly become cone-shaped, causing myopia (short-sightedness). If this becomes a problem the lens can be replaced, in an operation similar to ordinary cataract surgery.
- White flecks can also be detected by using an ophthalmoscope to look at the retina – the nerve layer at the back of the eyes. They don’t affect vision but they can help doctors to diagnose the condition.
- The front of the eyes can become dry, requiring treatment with artificial tear drops.
Diagnosis
If Alport syndrome is suspected, blood and urine tests will be done to check your kidney function and look for traces of blood and protein in your urine.
A kidney biopsy (a medical procedure to take small samples of the kidney to look at under the microscope) may also be required to make an accurate diagnosis.
Doctors will also check for high-tone deafness, look for possible signs in your eyes and ask if you have a known family history of chronic kidney disease or blood in the urine.
Because Alport syndrome is genetic, it can be helpful to analyse your DNA to look for the gene abnormalities that are known to cause the condition. If a genetic mutation is found, a kidney specialist can give you advice about the chances of family members being affected and how relatives can be screened for the condition, if this is requested.
So far, several hundred different gene mutations have been identified, as nearly every family has its own unique mutation.
Treatment
If the condition is detected at an early stage it may be possible to slow down your rate of kidney disease by using drugs called ACE Inhibitors to lower blood pressure.
Regular blood and urine tests are also usually carried out to gauge kidney function and you may also be offered treatments if you develop high blood pressure, anaemia or bone weakness.
You may also be encouraged to help preserve your kidney health by:
- Eating a healthy diet
- Maintaining a healthy weight
- Taking regular exercise
- Avoiding the use of non-steroidal anti-inflammatory drugs
Even though women with X-linked Alport syndrome are less severely affected than men, they should also be checked regularly and take the same precautions to preserve kidney health.
Disease progression
Some people with Alport Syndrome may eventually need dialysis or a transplant. Transplanted patients usually do very well, and Alport Syndrome does not recur in the transplanted kidney. However, sometimes the transplanted kidney can be damaged by antibodies attacking the normal collagen present in the glomeruli.
Help for you
If you have been diagnosed with Alport syndrome and have any questions or concerns about your illness don’t hesitate to speak to your kidney specialist or your nurse specialist at the kidney unit.
You can also find further information, advice and helpful tips in our Just diagnosed and How can I help myself? sections.
- Watch Professor Neil Turner talk about Alport syndrome.
- Alport UK is a patient-led organisation that provides support and information for people with Alport syndrome.
- To contact the Alport Patient Support Group email: [email protected].
- Alport syndrome – Rare Renal
- Alport syndrome – EDREN
Reviewed April 2019
Pioneering new programme to drive Alport syndrome research - Kidney Research UK
In partnership with the Stoneygate Trust, we're launching The Stoneygate and Kidney Research UK Alport Research Hub to accelerate research, transform early diagnosis and to develop specific treatments for Alport syndrome.
The programme is designed to make sure the best research happens with the best people in the most efficient way and this model of funding could be the way we tackle many different kidney diseases and conditions in the future.
Action for Alports
The Action for Alports campaign was launched in 2011, initiated by parent Deborah Fielding, to raise money to fund specific research into Alport syndrome and has gained support from many patients and their families.
The campaign aims to:
Raise awareness and understanding of the illness
Provide better care and facilitate faster diagnosis
Improve management for those affected by the illness
Ensure a better future for Alport patients and their families.
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