Clinical features and molecular analysis of arginine-vasopressin neurophysin II gene in long-term follow-up patients with idiopathic central diabetes insipidus.
BACKGROUND
Central diabetes insipidus (DI) characterized by polyuria, polydipsia and inability to concentrate urine, has different etiologies including genetic, autoimmune, post-traumatic, among other causes. Autosomal dominant central DI presents the clinical feature of a progressive decline of arginine-vasopressin (AVP) secretion.


OBJECTIVE
In this study, we characterized the clinical features and sequenced the AVP-NPII gene of seven long-term follow-up patients with idiopathic central DI in an attempt to determine whether a genetic cause would be involved.


METHODS
The diagnosis of central DI was established by fluid deprivation test and hyper-tonic saline infusion. For molecular analysis, genomic DNA was extracted and the AVP-NPII gene was amplified by polymerase chain reaction and sequenced.


RESULTS
Sequencing analysis revealed a homozygous guanine insertion in the intron 2 (IVS2 +28 InsG) of the AVP-NPII gene in four patients, which represents an alternative gene assembly. No mutation in the code region of the AVP-NPII gene was found.


CONCLUSIONS
The homozygous guanine insertion in intron 2 (IVS2 +28 InsG) is unlikely to contribute to the AVP-NPII gene modulation in DI. In addition, the etiology of idiopathic central DI in children may not be apparent even after long-term follow-up, and requires continuous etiological surveillance.
Departamento de Fisiologia, Universidade de São Paulo, Ribeirão Preto, SP, Brasil.
Sergio L
SL
Batista
Ayrton C
AC
Moreira
Jose
J
Antunes-Rodrigues
Margaret de
Md
Castro
Lucila L K
LL
Elias
Paula C L
PC
Elias
D002648:Child; D002675:Child, Preschool; D020790:Diabetes Insipidus, Neurogenic / Q000175:diagnosis* / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007438:Introns / Q000235:genetics; D008297:Male; D016254:Mutagenesis, Insertional / Q000235:genetics; D009481:Neurophysins / Q000235:genetics*; D011498:Protein Precursors / Q000235:genetics*; D014667:Vasopressins / Q000235:genetics*
C438657:AVP protein, human; D009481:Neurophysins; D011498:Protein Precursors; D014667:Vasopressins