Bartter Syndromes are inherited disorders of the kidney that cause salts and water to be lost from the body in the urine. The information below covers types 1, 2 and 4 of Bartter Syndrome and points out the differences between them. For practical reasons Bartter Syndrome type 3 and Gitelman Syndrome are dealt with separately.
In Types 1, 2 and 4 Bartter’s, the loss of salt and water into the urine may be severe, especially in infants, and patients risk becoming dehydrated.
Typically these types of Bartter Syndrome are identified in infancy or early childhood. Boys and girls are affected equally. They often come to medical attention because the child doesn’t thrive. Infants may be thirsty but difficult to feed, have recurrent vomiting and be lethargic. Children may have vomiting, fatigue or muscle weakness, and muscle spasms (tetany) or cramp.
Sometimes there are features of the condition before birth. Most notable is an excess of the amniotic fluid surrounding the developing baby in the womb. This is associated with premature delivery. Generally, the earlier a person develops the features of Bartter Syndrome the more severe the condition will be.
If Bartter patients get an infection such as the ‘flu or diarrhoea they can become seriously ill very quickly. In this situation they may need urgent admission to hospital for fluids to be replaced intravenously (by drip). They will need blood tests to identify exactly how much salt and fluid is needed.
Also there is increased excretion of calcium in the urine, and calcium deposits in the kidneys. Although these can be harmful to the kidney, people with Bartter Syndromes are unlikely to need dialysis or a kidney transplant.
A first step is to make the correct diagnosis. Blood tests show a low concentration of potassium and raised level of bicarbonate in plasma (hypokalaemic alkalosis). These features are permanent unless treated. However in Bartter Type 2, infants may have a high concentration of potassium in their blood for the first few weeks of life before switching to the typical lower levels.
Bartter Syndrome is divided up into sub-types according to the different genetic causes of the condition.
- Bartter Syndromes type 1 and 2 are clinically similar.
- Bartter Syndrome type 3 is often similar to Gitelman Syndrome and is dealt with separately.
- Bartter Syndrome type 4 has the added problem of deafness. This deafness is of sensori-neural type, the problem being in translating the vibration of sound into nerve impulses in the inner ear. Unfortunately the hearing loss cannot be reversed, but hearing aids may be prescribed, and audiological evaluation and follow-up are important.
Visit the Clinicians page for more information on the different types of Bartter Syndrome.
Genetic investigation and advice can be helpful. See How the disease works below.
Treatment aims to ‘top up’ the body’s level of potassium and salt, making good the losses that occur in the urine. Adjusting the diet to include foods that are high in salt and potassium is important (see dietary needs).
Most patients will need to take potassium (K) supplements every day, to help replace what is lost in the urine. These can be either in liquid or tablet form. Sometimes high doses are needed which can be difficult to digest and may cause unpleasant side effects like abdominal pains and diarrhoea. SlowK and Kay-Cee-L Liquid are preferable to SandoK. (Visit the Clinicians page for more information on supplements).
Non-steroidals such as indomethacin help the kidneys hold on to the potassium and water that the body needs.
Bartter Syndromes are life long conditions. People with these conditions need to stay on treatment and have regular hospital appointments and blood tests. The amount of supplements and medicines needed are likely to change over time, particularly in growing children. It is therefore important to remain on the correct amount of treatment to balance the body’s salt levels and prevent complications. Without treatment potassium levels in the blood could fall very low without the patient being aware of it, and can cause heart rhythm problems.
The second Gitelman and Bartter Syndrome Patient Information Day was held on Saturday 13th June 2015 at the Resource for London. For further details please click here or visit the new patient information website.
A report of the first Patient Information Day from 2011 can be found here.
Bartter Syndromes can affect boys and girls equally. Each condition is caused by changes in a gene that is important for moving salt around in the kidneys.
- In Type 1 Bartter syndrome this gene is called SLC12A1
- In Type 2 Bartter this gene is called ROMK2
- Type 4 Bartter syndrome is caused by changes in one or two of three genes, BSND (Barttin), CLCNKA and CLCNKB
Everyone has 2 copies of the gene involved, one from each parent:
- Healthy people have two normal copies
- Carriers have one copy that works normally and one that doesn’t. Carriers are usually perfectly healthy because the normal copy can still do its job.
- In patients with the condition, neither copy works normally. The gene can’t do its job properly and so the kidneys leak salt and potassium into the urine
Bartter Syndromes can be passed on from parents to children depending on their genes.
- If one parent has Bartter Syndrome and their partner has normal genes, then none of the children they have together will be affected. However all of their children will get one copy of the abnormal gene and will be carriers.
- If both parents are carriers then there is a 1 in 4 chance that their child will inherit both copies of the abnormal gene and have the condition. This is described as autosomal recessive inheritance. If these parents have an unaffected child there is a 2 out of 3 chance that that individual will be a carrier.
The diagram below explains how this works
a = gene with mutation A = gene without mutation
People with Bartter Syndromes are likely to know they’ve got it. Carriers on the other hand are healthy people and may not know they have an abnormal gene. The chance of someone in the general population being a carrier is less than 1 in 100 (less than 1 in 1000 for Type 4). In family members of Bartter patients (for example in cousins) the chance of being a carrier is higher.
In Bartter Syndromes a DNA test may be useful. This is a simple blood test that looks at the genes that cause the condition. Some people find this information helpful when planning a family, to see whether their partner is a carrier. Other family members might also want their DNA examined. This can be arranged through their doctor, a renal clinic or a geneticist.
The Tubulopathy Rare Disease Group (RDG) is working with international partners with the aim of finding new and improved treatments, and to empower patients. To do this the RDG is registering patients with these conditions in the National Renal Rare Disease Registry (RaDaR). The registry will be used to find suitable participants for future research trials into the effectiveness of new treatments.
If you are interested in finding out more about RaDaR or the activity of the RDG please visit the Tubulopathy RDG page.