A novel point mutation in the translation initiation codon of the pre-pro-vasopressin-neurophysin II gene: Cosegregation with morphological abnormalities and clinical symptoms in autosomal dominant neurohypophyseal diabetes insipidus

Autosomal dominant neurohypophyseal diabetes insipidus (ADNDI) is a rare variant of idiopathic central diabetes insipidus. Several different mutations in the human vasopressin-neurophysin II (AVP-NP II) gene have been described. We studied nine family members from three generations of an ADNDI pedigree at the clinical, morphological, and molecular levels. AVP concentrations were measured during diagnostic fluid restriction tests. Coronal and sagittal high resolution T1-weighted images of the pituitary were obtained from affected and healthy family members. PCR was used to amplify the AVP-NP II precursor gene, and PCR products were directly sequenced. Under maximal osmotic stimulation, AVP serum levels were close to or below the detection limit in affected individuals. Magnetic resonance imaging studies revealed the characteristic hyperintense ("bright spot") appearance of the posterior pituitary in two healthy family members. This signal was absent in all four ADNDI patients examined. The coding sequences...