Hereditary Neurohypophyseal Diabetes Insipidus

Neurohypophyseal diabetes insipidus (DI) is most often caused by trauma, including operations, and infiltrating processes in the hypothalamic-pituitary region. Irradiation, ischemia, infections, or autoimmunity can also underlie the disease. Since the middle of the 19th century, familial forms of neurohypophyseal DI have been described. Most commonly, the disease is transmitted in an autosomal-dominant fashion; very rarely, autosomal-recessive inheritance has been observed. Hereditary neurohypophyseal DI is caused by mutations in the gene encoding the antidiuretic hormone vasopressin (AVP) and its carrier protein neurophysin II (NPII). Symptoms result from the lack of hormone, or from the inability of mutant AVP to activate its renal receptor, and respond to treatment with desmopressin (DDAVP). Dominant mutations cause retention of the hormone precursor in the endoplasmic reticulum (ER) of vasopressinergic neurons in the hypothalamus, resulting in cellular dysfunction and eventually neuronal death. This so-called "neurotoxicity hypothesis" was initially established on the basis of autopsy studies in affected humans and has been supported by heterologous cell-culture expression experiments and murine knock-in models. Current data show that retained mutants fail to be eliminated by the cell's quality control system and accumulate in fibrillar aggregations within the ER. Autosomal-dominant neurohypophyseal DI may thus be viewed as a neurodegenerative disease confined to vasopressinergic neurons.