CFTR and Pendred syndrome: Finally, in ISCs of the mammalian airway mucociliary epithelium, Foxi1 also regulates the expression of cystic fibrosis transmembrane conductance regulator, and mutations in FOXI1 and its transcriptional target solute carriers cause Pendred syndrome and hearing loss, male infertility, and distal renal tubular acidosis [2,13–15].