Developmental delay occurred in 90% of individuals, and movement disorders in 60% (tremor, ataxia, myoclonus, dystonia, chorea, tics). Keywords: KCNN2; myoclonus-dystonia; tremor EN KCNN2 myoclonus-dystonia tremor S9 S12 4 09/20/22 20220903 NES 220903 The number of genes associated with early-onset movement disorders has expanded significantly in recent years.1,2 Increasingly, these disorders are discovered via next-generation sequencing (NGS) methods.2 Given the widespread use of NGS across many clinical and non-clinical settings, the discovery of incidental genetic findings is not uncommon.3 Furthermore, while the unbiased and comprehensive genetic evaluation achieved by NGS leads to a significantly increased diagnostic yield for neurological disorders, such methods frequently identify previously unobserved variants for which clinical significance is unclear.4,5 Since it is likely that such variants in genes associated with movement disorders will be increasingly detected by clinicians and researchers from other specialties, the significance of such findings may need to be determined by a movement disorders specialist. Jerk-locked EEG-EMG evaluation showed no short-latency EEG spike preceding EMG discharges, there were no abnormal responses to median nerve stimulation, and median nerve somatosensory evoked potentials showed normal amplitudes. Our patient, with a novel mutation in I KCNN2 i , adds to the small number of patients with neurodevelopmental movement disorders associated with this gene. [Extracted from the article]