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Updated: Aug 23, 2025
Author Spotlight: Studying Clinical Characters and Epilepsy Outcomes After Frontal Disconnection in Patients with MOGHE
Published on: August 16, 2024
Clinical Features, Neuropathology, and Surgical Outcome in Patients With Refractory Epilepsy and Brain Somatic
Carmen Barba1, Ingmar Blumcke1, Melodie R Winawer1
1From the IRCCS Meyer Children's Hospital (C.B., V.C., L.D.I., L.M., R.G.), Florence, Italy; University of Florence (C.B., L.G., R.G.), Florence, Italy; University Hospital Erlangen (I.B.), Germany; Columbia University (M.R.W., P.D.C.), New York, NY; Neurorehabilitation and Epileptology (T.H., I.M.), Vogtareuth, Germany; PMU Salzburg (T.H.), Austria; Yonsei University College of Medicine (H.-C.K., H.J.S.), Seoul, Republic of Korea; Rothschild Foundation Hospital (M.C.), Paris, France; Krankenhaus Mara (C.G.B., F.G.W., A.G., T.P.), Bielefeld University, Medical School, Germany; Charles University (B.H., B.S., L.K., P.K.), 2nd Faculty of Medicine and Motol University Hospital, Prague, Czech Republic; Stanford University (B.E.P., H.V.), School of Medicine Stanford, CA; Boston Children's Hospital and Harvard Medical School (H.G.W.L., E.Y., A.P.), MA; Society of Epilepsy Research (F.G.W.), Bielefeld, Germany; Case Western Reserve University (J.A.L.-R.), OH; Cleveland Clinic (J.A.L.-R., D.L.), Cleveland, OH; Sorbonne University (Sara Baldassari, Stéphanie Baulac), Paris Brain Institute (ICM), INSERM, CNRS, AP-HP, Pitié-Salpêtrière Hospital, France; Lucile Packard Children's Hospital at Stanford University (G.A.G.), School of Medicine Stanford, CA; Korea Advanced Institute of Science and Technology (A.K., J.H.L.), Daejeon, South Korea; University of Maryland School of Medicine (P.B.C.), Baltimore, MD; and Broad Institute of Harvard and M.I.T (D.L.), Cambridge, MA.
Background And Objectives:
The SLC35A2 gene, located at chromosome Xp11.23, encodes for a uridine diphosphate-galactose transporter. We describe clinical, genetic, neuroimaging, EEG, and histopathologic findings and assess possible predictors of postoperative seizure and cognitive outcome in 47 patients with refractory epilepsy and brain somatic SLC35A2 gene variants.
Methods:
This is a retrospective multicenter study where we performed a descriptive analysis and classical hypothesis testing. We included the variables of interest significantly associated with the outcomes in the generalized linear models.
Results:
Two main phenotypes were associated with brain somatic SLC35A2 variants: (1) early epileptic encephalopathy (EE, 39 patients) with epileptic spasms as the predominant seizure type and moderate to severe intellectual disability and (2) drug-resistant focal epilepsy (DR-FE, 8 patients) associated with normal/borderline cognitive function and specific neuropsychological deficits. Brain MRI was abnormal in all patients with EE and in 50% of those with DR-FE. Histopathology review identified mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy in 44/47 patients and was inconclusive in 3. The 47 patients harbored 42 distinct mosaic SLC35A2 variants, including 14 (33.3%) missense, 13 (30.9%) frameshift, 10 (23.8%) nonsense, 4 (9.5%) in-frame deletions/duplications, and 1 (2.4%) splicing variant. Variant allele frequencies (VAFs) ranged from 1.4% to 52.6% (mean VAF: 17.3 ± 13.5). At last follow-up (35.5 ± 21.5 months), 30 patients (63.8%) were in Engel Class I, of which 26 (55.3%) were in Class IA. Cognitive performances remained unchanged in most patients after surgery. Regression analyses showed that the probability of achieving both Engel Class IA and Class I outcomes, adjusted by age at seizure onset, was lower when the duration of epilepsy increased and higher when postoperative EEG was normal or improved. Lower brain VAF was associated with improved postoperative cognitive outcome in the analysis of associations, but this finding was not confirmed in regression analyses.
Discussion:
Brain somatic SLC35A2 gene variants are associated with 2 main clinical phenotypes, EE and DR-FE, and a histopathologic diagnosis of MOGHE. Additional studies will be needed to delineate any possible correlation between specific genetic variants, mutational load in the epileptogenic tissue, and surgical outcomes.
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