AVPR2 gene: MedlinePlus Genetics (original) (raw)

arginine vasopressin receptor 2

Normal Function

The AVPR2 gene provides instructions for making a protein known as the vasopressin V2 receptor. This receptor works together with a hormone called arginine vasopressin (AVP), which is sometimes also called antidiuretic hormone (ADH). The vasopressin V2 receptor is found in the kidneys in structures called collecting ducts, which are a series of small tubes that reabsorb water from the kidneys into the bloodstream.

The interaction between AVP and the vasopressin V2 receptor triggers chemical reactions that control the body's water balance. When a person's fluid intake is low or when a lot of fluid is lost (for example, through sweating), AVP is released from the brain, where it is produced and stored. In the kidneys, this hormone attaches (binds) to the vasopressin V2 receptor and directs the kidneys to concentrate urine by reabsorbing some of the water back into the bloodstream. When fluid intake is adequate, the brain releases less AVP. At these times, less water is reabsorbed into the bloodstream and the urine is more dilute.

Arginine vasopressin resistance

Hundreds of variants (also called mutations) in the AVPR2 gene have been identified in people with arginine vasopressin resistance. People with this condition produce an excessive amount of urine (polyuria), which depletes the amount of water in the body. This water loss also leads to excessive thirst (polydipsia). Most of the variants that cause this condition produce a vasopressin V2 receptor protein that is folded incorrectly. The misfolded protein remains trapped within the cell, where it is unable to reach the cell surface to interact with AVP. Less common variants in the AVPR2 gene prevent the production of any vasopressin V2 receptor protein or lead to a version of the protein that can reach the cell surface but cannot bind to AVP.

Without functional vasopressin V2 receptors, the kidneys are unable to respond to signals from AVP. As a result, collecting ducts do not reabsorb water as they should, leading to polyuria in people with arginine vasopressin resistance.

More About This Health Condition

Other disorders

Variants in the AVPR2 gene have been found to cause another kidney disorder known as nephrogenic syndrome of inappropriate antidiuresis (NSIAD). This condition is characterized by low levels of salt in the blood (hyponatremia), which can lead to brain swelling and other serious complications. NSIAD also causes the blood to be abnormally dilute (serum hypo-osmolality).

The AVPR2 gene variants associated with NSIAD change single protein building blocks (amino acids) in the vasopressin V2 receptor protein. These variants lead to a receptor protein that is constantly turned on (constitutively activated), even in the absence of AVP. As a result, water is reabsorbed into the bloodstream regardless of fluid intake, and urine is highly concentrated. These abnormalities disrupt the body's water balance, causing hyponatremia and serum hypo-osmolality.

Other Names for This Gene

References