Background: Nephrogenic diabetes insipidus (NDI) is a rare disorder characterized by renal resistance to arginine vasopressin, most commonly caused by pathogenic variants in the AVPR2 gene. While X-linked NDI classically affects males, heterozygous females may exhibit variable clinical expression. Certain AVPR2 variants are associated with partial NDI and milder phenotypes. Methods: We conducted a retrospective family study of a multigenerational Greek pedigree with suspected hereditary NDI. Cli