AVP-NPII gene mutations and clinical characteristics of the patients with autosomal dominant familial central diabetes insipidus

Background Familial central diabetes insipidus (DI), usually an autosomal dominant disorder, is caused by mutations in arginine vasopressin - neurophysin II ( AVP - NPII ) gene that leads to aberrant preprohormone processing and gradual destruction of AVP-secreting cells. Objective To determine clinical and molecular characteristics of patients with familial central DI from two different Turkish families. Materials and methods The diagnosis of central DI was established by 24-h urine collection, water deprivation test, and desmopressin challenge. To confirm the diagnosis of familial central DI, the entire coding region of AVP - NPII gene was amplified and sequenced. A total of eight affected patients and three unaffected healthy relatives from two families were studied. Results Genetic analysis revealed a previously reported heterozygous mutation (p.C98X) in family A, and a heterozygous novel mutation (p.G45C) in family B, both detected in exon 2 of AVP - NPII gene. When we compared the clinical characteristics of the two families, it was noticed that as the age of onset of symptoms in family A ranges between 4 and 7 years, it was