Successful kidney transplantation in a patient with late-onset type II Bartter syndrome: A rare case report.

Bartter syndrome (BS) is a rare autosomal recessive disorder characterized by inherited salt-losing tubulopathies. Distinguished into six types, each associated with specific genetic mutations, type II is particularly rare in adults and typically presents early. This report documents a rare case of an adult diagnosed with type II Bartter syndrome that progressed to end-stage kidney disease (ESKD) and underwent successful kidney transplantation, marking it a first of its kind in India and only the second globally. The patient, diagnosed in adulthood, experienced a delayed onset of symptoms, including uremia, hypocalcemia, and medullary nephrocalcinosis, which progressed to ESKD. Genetic testing confirmed a homozygous missense mutation in the KCNJ1 gene. After prolonged hemodialysis, a kidney transplant from a deceased donor resulted in successful graft function and symptom resolution. This case underlines the phenotypic variability of Bartter syndrome and provides critical insights into managing severe, late-onset cases through transplantation.