GRM1 and Epileptic encephalopathy: Although, other less common syndromes have variably been reported, such as isolated epilepsy/epileptic encephalopathy (15/94, 16%; GABAAR, GlyR), isolated psychiatric disorders (D2R, GABAAR), Tourette's syndrome, Sydenham's chorea, PANS/PANDAS (D2R), SPS (GlyR, GABAAR), PERM (GlyR, DPPX), acute cerebellar syndrome (mGluR1), and sleep and movement disorders (IgLON5) (Table 2A).