title: Utility of AVP gene testing in familial neurohypophyseal diabetes insipidus.
abstract: BACKGROUND
  Familial neurohypophyseal diabetes insipidus (FNDI) is a rare disorder resulting from arginine vasopressin (AVP) gene mutations. A partial defect in AVP secretion occurs early in the course of FNDI and may not be detected by a water deprivation test (WDT). Testing for AVP gene mutations may confirm a diagnosis of FNDI when a WDT is inconclusive and may also predict individuals who will later develop FNDI.
  
  
  OBJECTIVE
  To test the utility of AVP gene analysis in confirming the diagnosis of FNDI.
  
  
  METHODS
  Five families (20 subjects, 14 symptomatic and six asymptomatic) with FNDI and nine children with idiopathic neurohypophyseal diabetes insipidus (INDI).
  
  
  METHODS
  Genomic DNA was analysed for AVP gene mutations using polymerase chain reaction (PCR) amplification and sequencing.
  
  
  RESULTS
  Heterozygous AVP gene mutations were found in all subjects with FNDI but none of the ICDI patients. Each family had their own distinct mutation. We identified two novel mutations (C44W and C105S). One asymptomatic subject developed diabetes insipidus (DI) 4 months after detection of an AVP gene mutation. The WDT suggested partial DI in 4/6 but was normal in 2/6 children with FNDI.
  
  
  CONCLUSIONS
  AVP gene testing allowed diagnostic confirmation of FNDI when the WDT was inconclusive in symptomatic children, therefore obviating the need for a repeat WDT and enabling earlier initiation of appropriate treatment. AVP gene testing also has the potential to identify which asymptomatic children will later develop FNDI.
authors.affiliation: Paediatric Endocrinology and Diabetes, Mater Children's Hospital, Brisbane, Australia.
authors.forename: Sridhar
authors.initials: S
authors.lastname: Chitturi
authors.forename: Mark
authors.initials: M
authors.lastname: Harris
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Thomsett
authors.forename: Francis
authors.initials: F
authors.lastname: Bowling
authors.forename: Ivan
authors.initials: I
authors.lastname: McGown
authors.forename: David
authors.initials: D
authors.lastname: Cowley
authors.forename: Gary M
authors.initials: GM
authors.lastname: Leong
authors.forename: Jennifer
authors.initials: J
authors.lastname: Batch
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Cotterill
mesh_terms: D001127:Arginine Vasopressin / Q000235:genetics* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D020790:Diabetes Insipidus, Neurogenic / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D010904:Pituitary Gland, Posterior / Q000002:abnormalities; D014868:Water Deprivation
chemical_list: D001127:Arginine Vasopressin