Contrary to our original hypothesis, however, and in contrast to findings from the FXS mouse, the results of our electrophysiological and histologic experiments demonstrate that, in DGGC and GCL PV+-INs, loss of a single copy of the Cyfip1 gene is not sufficient to produce changes in either phasic or tonic GABAergic inhibition. The gene discussed is CYFIP1; the disease is fragile X syndrome.