Independent observations that connect hypomagnesemia and renal Mg wasting with disruption of the FXYD2–αβ interaction include identification of mutations in the hepatocyte nuclear factor (HNF‐1B), a transcription factor, expressed in various organs, including kidneys, and associated with abnormal renal development (Adalat et al. Here, HNF1B is linked to familial primary hypomagnesemia.