A critical question in CFKD is to what extent the increased prevalence of AKI and CKD results from extrarenal causes, including CF lung disease and nephrotoxic drug exposure, as opposed to intrinsic susceptibility to tubulointerstitial or glomerular injury resulting from renal CFTR dysfunction, decreased nephron endowment [170], pH sensitivity, or pro-fibrotic signaling. This evidence concerns the gene CFTR and acute kidney injury.