SLC9A3 and congenital bilateral aplasia of vas deferens from CFTR mutation: Mutations in the solute carrier family 9 sodium/hydrogen-exchanger isoform 3 gene (SLC9A3/NHE3) have been identified as a possible basis of Taiwanese CBAVD [11]. SLC9A3 encodes an ion channel regulated by CFTR and accumulates at the apical membrane of renal proximal tubules and intestinal epithelial cells to mediate NaCl and HCO3− absorption [12–15].