8067 AVP Gene Mutation: A Rare Cause of Diabetes Insipidus

Abstract Disclosure: N. Navrange: None. M. Williams: None. P. Madhavan: None. Introduction: Arginine vasopressin deficiency (AVP-D), also known as neurohypophyseal or central diabetes insipidus (DI), is marked by a reduced secretion of arginine vasopressin (AVP), resulting in polyuria and polydipsia. AVP-D is a rare disorder, with a prevalence of 1 in 25,000. Typically, the disorder is acquired. However, in less than 5% of cases, it has a genetic etiology. The majority of mutations in the AVP gene are autosomal dominant. Normally, AVP encodes vasopressin, also known as antidiuretic hormone (ADH). It plays a key role in the reabsorption of water in the kidney, the regulation of blood pressure, and controlling the body’s osmotic balance. However, a mutation in this gene leads to a deficient release of ADH, leading to reduced reabsorption of water in the collecting duct and decreased ability to concentrate urine. This results in increased urine output and excessive thirst. The onset and severity of symptoms varies between individuals. Case Report: In this report, we discuss the case of a 40-year-old Caucasian female with familial neurohypophyseal diabetes insipidus. The patient presented to the clinic for follow-up care of DI and hyponatremia. She received her DI diagnosis before the age of 5 and has multiple family members with the condition including her maternal grandfather, mother, and 2 siblings. Additionally, she suspected one of her children was exhibiting excessive urination. Past medical history is also significant for seizure disorder, postpartum cardiomyopathy, Chiari malformation type I and remote history of substance abuse. Vitals were stable with blood pressure of 122/86 mmHg, heart rate of 93 bpm, body mass index of 31.8. Physical exam was unremarkable except for obesity. She is currently managed with DDAVP 0.05 mg twice daily. Previously, imaging was performed to rule out pituitary abnormalities. The patient was referred for genetic testing due to her family history and was found to have a previously described rare autosomal dominant mutation of the AVP protein. The single nucleotide polymorphism in exon 1 results in a missense mutation substituting an alanine nucleotide for threonine (c.55G>A). The patient was counseled to share these results with her children’s pediatrician, as they could benefit from testing for the mutation. Discussion: Our patient has a pathogenic variant in AVP, specifically a missense mutation from Alanine to Threonine at codon 19 of the AVP protein. This mutation is associated with autosomal dominant neurohypophyseal diabetes insipidus. This case provides an example of a rare cause of neurohypophyseal diabetes insipidus and emphasizes the necessity of obtaining detailed family history in patients who have DI and considering genetic testing for patients with suspicion for familial involvement. Presentation: 6/2/2024