A novel AVPR2 missense mutation in an Asian family with inherited nephrogenic diabetes insipidus: A case report

Oral disintegrating desmopressin tablet is effective for partial congenital nephrogenic diabetes insipidus with AVPR2 mutation: a case report

Congenital nephrogenic diabetes insipidus (NDI) is a rare disease that causes polydipsia and polyuria, and there are currently no effective treatments for most cases, particularly severe ones. The present report describes the case of a 1-yr-5-mo-old male patient with partial congenital NDI who was successfully treated with oral disintegrating 1-deamino-8-D-arginine vasopressin (DDAVP). The patient presented with poor weight gain and polydipsia (fluid, 1.5 L/d) and received a diagnosis of NDI after genetic analysis revealed an AVPR2 mutation (c.383A>C, p.Y128S). His water-restricted urine osmolality increased from 360 mOsm/kg/H₂O to 667 mOsm/kg/H₂O after subcutaneous AVP injection, indicating that he had some urine concentrating ability. Oral disintegrating DDAVP therapy was started at 360 µg/d with hydrochlorothiazide and increased to 720 µg/d without any adverse effects. A 30% decrease in urine output and water intake was followed by an increase in body weight. The present study is the first to report the effectiveness and safety of oral disintegrating DDAVP in a patient with partial congenital NDI due to an AVPR2 gene mutation. The severity of NDI at which DDAVP therapy is the most effective remains to be determined.

Identification of a Novel Arginine Vasopressin Receptor 2 Mutation (p.V183M) in a Chinese Family with Nephrogenic Diabetes Insipidus

Loss of function of arginine vasopressin receptor 2 (AVPR2) may affect the recognition and binding of arginine vasopressin (AVP) which, in turn, may prevent the activation of Gs/adenylate cyclase and reduce the reabsorption of water by renal tubules and combined tubes. Finally, the organism may suffer from nephrogenic diabetes insipidus (NDI), a kind of kidney disorder featured by polyuria and polydipsia, due to a break of water homeostasis. In this study, we enrolled a Chinese family with polyuria and polydipsia. The proband presented abnormal fluid intake and excessive urine output. A water deprivation and AVP stimulation test further indicated that this patient had NDI. By sequencing known causative genes for diabetes insipidus, we identified a novel mutation in AVPR2 (c.547G>A; p.V183M) in the family. This mutation, located in a conserved site of AVPR2 and predicted to be disease-causing by informatics programs, was absent in our 200 controls and other public databases. Our study not only further confirms the clinical diagnosis, but also expands the spectrum of AVPR2 mutations and contributes to genetic diagnosis and counseling of patients with NDI.