Moreover, mice with Usp9x-deficient neurons develop abnormal neuronal connectivity.[12, 14, 25, 26] A similar apparent discrepancy has been observed in the case of the SCN1A gene (which codes for the NAV1.1 channel) and its fly homologue para. Here, the great majority of 68 different mutations in para suppress seizures in the fly,[27–31] yet human SCN1A mutations are associated with severe epileptic encephalopathies, febrile seizure syndromes, and Dravet syndrome. The gene discussed is USP9X; the disease is encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.