The Role of Genetic Testing in Diagnosing ADTKD-HNF1B in a Pregnant Woman

Autosomal dominant tubulointerstitial kidney disease (ADTKD) accounts for approximately 2%‑5% of monogenic causes of chronic kidney disease (CKD) and remains frequently underrecognized due to its heterogeneous clinical presentation. We report the case of a 37‑year‑old pregnant woman diagnosed with CKD, initially attributed to chronic pyelonephritis. She presented with bilateral renal cysts, electrolyte abnormalities, uterine malformation, and a family history of CKD. Genetic testing was pursued based on the phenotypic features, identifying a novel heterozygous HNF1B variant, c.785_786dup p.(Ala263Argfs*3), classified as likely pathogenic. Subsequent familial screening revealed that the patient’s mother, who was on hemodialysis for CKD of unknown etiology, carried the same mutation, leading to the reclassification of her CKD etiology as ADTKD related to HNF1B. This case highlights the clinical variability and diagnostic challenges of HNF1B‑related ADTKD, emphasizing the crucial role of genetic testing in identifying the etiology and improving disease understanding among nephrologists.