title: Clinical features, diagnosis and molecular studies of familial central diabetes insipidus.
abstract: BACKGROUND
  Familial central diabetes insipidus (DI) is rare and is characterised by polydipsia and polyuria with a variable age of onset. The evaluation of arginine vasopressin (AVP) secretion in these individuals has been reported infrequently and only in adulthood.
  
  
  OBJECTIVE
  To describe the clinical features, diagnosis and molecular investigation of children affected by familial central DI.
  
  
  METHODS
  Functional studies of AVP secretion were undertaken in children from two kindreds with familial central DI. The AVP-neurophysin II (AVP-NPII) gene was also sequenced in symptomatic individuals.
  
  
  RESULTS
  In affected individuals, the result of the water deprivation test may be inconclusive. However, the hypertonic saline test identified both the severe and partial forms of AVP deficiency. A novel mutation of the AVP-NPII gene was identified by direct gene sequencing in both families.
  
  
  CONCLUSIONS
  This report highlights the progressive decline in AVP secretion with increasing age in this disorder and the usefulness of mutational analysis in these families. In symptomatic individuals, the hypertonic saline test may be a useful second-line investigation for functional studies of AVP secretion where molecular diagnostics are unavailable.
authors.affiliation: Department of Child Health, Cardiff University, Cardiff, UK. justin.davies@suht.swest.nhs.uk
authors.forename: J H
authors.initials: JH
authors.lastname: Davies
authors.forename: M
authors.initials: M
authors.lastname: Penney
authors.forename: A P
authors.initials: AP
authors.lastname: Abbes
authors.forename: H
authors.initials: H
authors.lastname: Engel
authors.forename: J W
authors.initials: JW
authors.lastname: Gregory
mesh_terms: D001127:Arginine Vasopressin / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D001769:Blood; D020790:Diabetes Insipidus, Neurogenic / Q000175:diagnosis* / Q000235:genetics*; D005091:Exons; D005260:Female; D006801:Humans; D007223:Infant; D009154:Mutation; D009481:Neurophysins / Q000235:genetics; D009994:Osmolar Concentration; D010375:Pedigree; D012150:Polymorphism, Restriction Fragment Length; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage; D017422:Sequence Analysis, DNA; D014556:Urine; D014868:Water Deprivation
chemical_list: D009481:Neurophysins; D012462:Saline Solution, Hypertonic; D001127:Arginine Vasopressin