AQP4 and Polyuria: In line with this idea, gene regulation studies in postmortem brain of PGRN-associated FTLD-U patients show deregulations of aquaporin-1 and AQP4 among the top 100 deregulated genes (Geo data sets GDS3459, GSE13162 [56]), raising the intriguing possibility that patients with PGRN-associated frontotemporal lobar degeneration may eventually develop symptoms of polyuria.