NDI patient manifest polyuria and polydipsia.[1] The symptoms of NDI range in their severity between individuals, owing to the heterogeneity of the mutations responsible for the disorder.[2] Approximately 90% of patients with an X-linked form of NDI (OMIM 304800), which affect male patients, are unable to concentrate their urine in response to the antidiuretic hormone, arginine-vasopressin (AVP). The gene discussed is AVP; the disease is Polydipsia.