Missense, splicing, and truncation mutations in SLC9A3, identified in nine patients from eight families lead to congenital sodium diarrhea (CSD).45 Two of these nine patients developed IBD at 4 and 16 years of age.45 SLC9A3 is an epithelial brush‐border Na/H exchanger that uses an inward sodium ion gradient to expel acids from the cell. Here, SLC9A3 is linked to inflammatory bowel disease.