JLE

Epileptic Disorders

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GNAO1-associated epileptic encephalopathy and movement disorders: c.607G>A variant represents a probable mutation hotspot with a distinct phenotype Volume 19, numéro 1, March 2017

Figure 1

Serial brain magnetic resonance imaging performed over four years demonstrating interval progressive volume loss involving cerebral hemispheres (more prominent in the left hemisphere). There was also volume loss in the cerebellum (more pronounced on the left), minimal non-specific T2/FLAIR hyper-intense foci in the white matter, and normal spectroscopy (not shown).

Figure 2

EEG (AP bipolar montage; LFF: 1 Hz; HFF: 70 Hz; sensitivity: 10 μV) epochs showing interictal (upper panel) and ictal (middle and lower panel) findings. Interictal epileptiform discharges can be seen asynchronously in the left frontal, left anterior temporal, right frontal, and right anterior temporal head regions, as well as diffusely bilaterally. Low-amplitude paroxysmal fast activity can also be seen in the right posterior temporal head region. Ictal onset (middle panel; arrows) was characterized by a diffuse sharp wave with central/parietal amplitude emphasis, followed by diffuse attenuation and superimposed low-amplitude fast activity, followed by 2-3 Hz sharply contoured polymorphic delta activity in a similar distribution. The seizure ends abruptly after 22 seconds (lower panel; arrow) with return of the interictal pattern. Clinically, the patient opened his eyes, had tonic extension of all four extremities (predominantly the legs), and a few clonic jerks of the arms towards the end of the seizure.

Figure 3

Alignment of amino acid sequences from vertebrate orthologs of GNAO1 demonstrating the evolutionary conservation of the GNAO1 variant G203R. The variant occurs in a region predicted to be a GTP binding site based on the sequence.