Diabetes insipidus (DI) is characterized by hypoosmotic polyuria related to deficiency of arginine-vasopressin (AVP) secretion (centraldiabetesinsipidus, CDI) or renalinsensitivity to AVP (nephrogenicdiabetesinsipidus, NDI).
We present here a unique case of partial X-linked NDI due to an AVPR2 splice site mutation; patients with diabetes insipidus of unknown etiology may harbor splice site mutations that are initially underestimated in their pathogenicity on sequence analysis.
This study evaluated whether dDAVP (a potent AVPR2 agonist) reduces sodium excretion in healthy humans (n = 6) and in patients with central (C; n = 2) or nephrogenic (N) diabetes insipidus (DI) as a result of mutations of either the aquaporin 2 gene (AQP2; n = 3) or AVPR2 (n = 10). dDAVP was infused intravenously (0.3 microg/kg body wt in 20 min), and urine was collected for 60 min before (basal) and 150 min after the infusion. dDAVP markedly reduced both urine flow rate and sodium excretion in healthy individuals.
The identification, characterization, and mutational analysis of three different genes, namely the prepro-arginine-vasopressin-neurophysin II gene (prepro-AVP-NPII), the arginine-vasopressin receptor 2 gene (AVPR2), and the vasopressin-sensitive water channel gene (aquaporin-2, AQP2), provide the basis for our understanding of three different hereditary forms of diabetes insipidus: autosomal dominant neurogenic diabetes insipidus, X-linked nephrogenic diabetes insipidus, and autosomal recessive nephrogenic diabetes insipidus, respectively.