For this reason, we considered all patients with GS or type 3 BS to be a homogeneous group, “SLT.” Phenotypic overlap also exists with HNF1B (which encodes the transcription factor HNF-1β); patients may present with typical electrolyte disturbances seen in GS, especially hypomagnesemia and hypocalciuria.36 The gene discussed is HNF1B; the disease is familial primary hypomagnesemia.