Diabetes insipidus is caused by either the lack of arginine-vasopressin (AVP) in central diabetes insipidus (CDI) or the resistance to the action of this hormone in nephrogenic diabetes insipidus (NDI). While the causes of CDI and NDI are mostly acquired, a small percentage is hereditary in either a dominant (CDI) or recessive manner (NDI). Familial CDI is typically of late onset and slowly progressive during the first few years of life, in contrast to the frequently severe dehydration seen soon after birth in patients with NDI. These differences in the clinical presentation and the genetic mode of transmission have become at least partly explicable with the characterization of the molecular defects in patients with CDI and NDI.
Over the past 4 years several mutations in the gene encoding the hypothalamic pre-pro-AVP-neurophysin II (AVP-NPII) precursor protein have been described (1–3). Both AVP and NPII are encoded by the same gene. The