Bartter Syndrome
Description
Bartter syndrome is a group of rare genetic disorders that affect the kidneys‘ ability to reabsorb salt (sodium and chloride). This leads to a buildup of salt in the urine and a loss of salt from the body, resulting in various symptoms like low blood pressure, dehydration, and electrolyte imbalances. This blog post will delve into the details of Bartter syndrome, covering its signs, causes, inheritance, diagnosis, management, and how individuals with Bartter syndrome can thrive.
Genes Involved
Bartter syndrome is caused by mutations in several genes, including:
- SLC12A1 (NKCC2): Involved in sodium and chloride reabsorption in the thick ascending limb of the loop of Henle.
- SLC12A3 (NCC): Responsible for sodium reabsorption in the distal convoluted tubule.
- KCNJ1 (ROMK): Encodes a potassium channel in the thick ascending limb of the loop of Henle.
- CLCNKB: Encodes a chloride channel in the thick ascending limb of the loop of Henle.
- BSND: Involved in chloride transport in the thick ascending limb of the loop of Henle.
- CASR: Encodes a calcium-sensing receptor, which regulates calcium levels in the body.
Recognizing the Signs and Symptoms
The symptoms of Bartter syndrome can vary depending on the severity of the condition and the specific gene affected. However, some common signs and symptoms include:
- Low blood pressure (hypotension)
- Dehydration
- Frequent urination
- Muscle cramps
- Fatigue
- Delayed growth
- Metabolic alkalosis (high blood pH)
- Hypokalemia (low potassium levels)
- Hypomagnesemia (low magnesium levels)
- Hypocalcemia (low calcium levels)
In severe cases, Bartter syndrome can lead to kidney failure.
Causes
Bartter syndrome is caused by mutations in genes involved in salt reabsorption in the kidneys. These mutations are inherited, meaning they are passed down from parents to their children. In some cases, the mutation may be spontaneous (de novo), meaning it occurs for the first time in the affected individual.
Inheritance/recurrence risk
Bartter syndrome is typically inherited in an autosomal recessive pattern. This means that a person needs to inherit two copies of the mutated gene, one from each parent, to develop the disorder. If both parents are carriers of the mutated gene, there is a 25% chance that their child will inherit both copies and develop Bartter syndrome, a 50% chance that their child will inherit one copy and be a carrier, and a 25% chance that their child will inherit neither copy and not be affected. In some cases, Bartter syndrome can be inherited in an autosomal dominant pattern. This means that a person only needs to inherit one copy of the mutated gene to develop the disorder.
