DNAJB11 is an endoplasmic reticulum (ER) co-chaperone that functions alongside the HSP70 chaperone HSPA5 (BiP) to coordinate protein folding, trafficking, and degradation. It binds unfolded protein substrates destined for ER-associated degradation (ERAD) and stimulates HSPA5 ATPase activity, facilitating proper protein maturation. DNAJB11 assembles as a native tetramer, a structural arrangement essential for substrate binding and coordinating both ER and extracellular proteostasis 1. The protein is particularly important for maturation and correct trafficking of PKD1 (polycystin-1). Monoallelic DNAJB11 loss-of-function variants cause atypical autosomal dominant polycystic kidney disease (ADPKD), a phenotypically distinct form characterized by non-enlarged or slowly enlarging kidneys with interstitial fibrosis, representing a hybrid between ADPKD and autosomal dominant tubulointerstitial kidney disease 2. Among 77 affected individuals identified across multiple studies, 32 reached end-stage renal disease with median age 75 years 3. DNAJB11-associated disease is considered a minor locus for ADPKD, similar in severity to PKD2-associated disease. Recent evidence indicates that biallelic loss of Dnajb11 in mouse models causes cystic kidney disease with cysts predominantly originating from proximal tubules and impaired PC1 cleavage as an underlying mechanism 4. Establishing precise molecular diagnosis of DNAJB11-kidney disease is clinically important for genetic counseling, prognosis, and selection of living kidney donors.