V2R mutations and nephrogenic diabetes insipidus

Area of Science:

• Nephrology
• Medical Genetics

Background:

• Nephrogenic diabetes insipidus (NDI) is characterized by impaired renal water reabsorption despite normal antidiuretic hormone (ADH) levels.
• Clinical manifestations include polyuria and polydipsia, stemming from a failure to concentrate urine maximally.
• NDI can arise from defects in vasopressin signaling, impaired osmotic gradient, or a combination thereof, encompassing various urinary concentrating defects.

Purpose of the Study:

• To elucidate the genetic basis and molecular mechanisms of inherited and acquired Nephrogenic Diabetes Insipidus (NDI).
• To differentiate NDI from neurohypophyseal diabetes insipidus based on genetic and physiological parameters.

Main Methods:

• Review of genetic mutations associated with NDI, including AVPR2 and AQP2 genes.
• Analysis of inheritance patterns (X-linked recessive, autosomal recessive, autosomal dominant) and associated OMIM entries.
• Clinical differentiation based on response to exogenous AVP and plasma AVP levels.

Main Results:

• Approximately 90% of congenital NDI cases are X-linked recessive, caused by mutations in the AVPR2 gene (OMIM 304800).
• About 10% of congenital NDI cases result from autosomal mutations in the AQP2 gene (OMIM 107777).
• Acquired NDI is primarily linked to long-term lithium administration.

Conclusions:

• Genetic defects in the vasopressin V2 receptor (AVPR2) and aquaporin-2 (AQP2) are the primary causes of inherited NDI.
• Understanding the genetic underpinnings is crucial for diagnosing and managing NDI, distinguishing it from central diabetes insipidus.
• Acquired NDI, often lithium-induced, presents a distinct etiological category requiring separate consideration.