Table 2.
Phenotypes of patients with somatic SLC35A2 mutations.
| Subject ID/ Sex | Epilepsy Type/ Seizures types | Age at first seizure /Age at surgery | Post-operative Engel score (time since surgery) | Preoperative MRI | Pathology | Neuropsych assessment | Localization | |
|---|---|---|---|---|---|---|---|---|
| Case 1 (Ser304Pro) /F | FE/FoS with impaired awareness | 13 yrs /17 and 18 yrs | Engel 1A after second surgery (20 mos) | 3T 1) Possible R MTS; 2) no lesion corresponding to epileptogenic focus* |
First procedure: no architectural abnormalities in GM or WM; patchy microgliosis Second procedure: CMS; subacute infarcts (likely due to electrode placement) |
Average intelligence; frontal dysfunction likely secondary to AEDs | R frontal: mid cingulate gyrus, R anterior cingulate gyrus, possible R SMA | |
| Case 2 (Leu113dup)/M | FE/FoS with impaired awareness, followed by secondary generalization | 2 yrs /13 yrs | Engel IV (12 mos) | 1.5T 1) Possible L MTS; 2) Slight ventricular enlargement; 3) No lesion corresponding to epileptogenic focus |
FCD Ia; CMS; Mild patchy microgliosis | Difficulty with auditory naming and contextual verbal learning/memory; Mild bilateral frontal dysfunction. | Posterior L cingulate and precuneate region | |
| Case 3 (Ser212 Leufs*9) /M | Fe/ FoS with impaired awareness, followed by secondary generalization | 17 yrs /23 yrs | Engel 1A (19 mos) | 3T normal |
Hypercellular with FCD Ia; reactive changes | Nondominant posterior hemisphere dysfunction | right posterior temporal-occipital lobe | |
| Case 4 (Arg55Leu) /M | Infantile spasms | 4 mo /2 yrs | Engel IV (24 mos) | 3T (4 mos) normal 3T (23 mos) (1) R fronto-temporal lesion, FCD vs gliosis; (2) R>L fronto-temporal dysmyelination |
Gliosis | At 28 months: at or below 3-month level in all domains | R frontal and temporal | |
| Case 5 (Ala253 Glyfs*100) /M | Epileptic spasms | 14 mo /7 yrs | Engel 1A (24 mos) | 3T (3 yrs) R frontal FCD |
Gliosis | At 7 years: delayed in all domains but ambulatory; conversant with behavioral dysregulation | R frontal |
FE = focal epilepsy, FoS = Focal seizures, CMS = Chaslin’s ; marginal sclerosis, LRE = localization-related epilepsy, AED = antiepileptic drug, FCD = focal cortical dysplasia MTS = Mesial Temporal Sclerosis, SMA = supplemental motor area, R=Right L=Left, WM = White matter, GM = White matter
*
a small periventricular signal abnormal abnormality was identified in post-hoc analysis (Figure 2).