Common genes and recurrent causative variants in 957 Asian patients with pediatric epilepsy.

OBJECTIVE: We aimed to identify common genes and recurrent causative variants in a large group of Asian patients with different epilepsy syndromes and subgroups. METHODS: Patients with unexplained pediatric-onset epilepsy were identified from the in-house Severance Neurodevelopmental Disorders and Epilepsy Database. All patients underwent either exome sequencing or multigene panels from January 2017 to December 2019, at Severance Children's Hospital in Korea. Clinical data were extracted from the medical records. RESULTS: Of the 957 patients studied, 947 (99.0%) were Korean and 570 were male (59.6%). The median age at testing was 4.91 years (interquartile range, 1.53-9.39). The overall diagnostic yield was 32.4% (310/957). Clinical exome sequencing yielded a diagnostic rate of 36.9% (134/363), whereas the epilepsy panel yielded a diagnostic rate of 29.9% (170/569). Diagnostic yield differed across epilepsy syndromes. It was high in Dravet syndrome (87.2%, 41/47) and early infantile developmental epileptic encephalopathy (60.7%, 17/28), but low in West syndrome (21.8%, 34/156) and myoclonic-atonic epilepsy (4.8%, 1/21). The most frequently implicated genes were SCN1A (n = 49), STXBP1 (n = 15), SCN2A (n = 14), KCNQ2 (n = 13), CDKL5 (n = 11), CHD2 (n = 9), SLC2A1 (n = 9), PCDH19 (n = 8), MECP2 (n = 6), SCN8A (n = 6), and PRRT2 (n = 5). The recurrent genetic abnormalities included 15q11.2 deletion/duplication (n = 9), Xq28 duplication (n = 5), PRRT2 deletion (n = 4), MECP2 duplication (n = 3), SCN1A, c.2556+3A>T (n = 3), and 2q24.3 deletion (n = 3). SIGNIFICANCE: Here we present the results of a large-scale study conducted in East Asia, where we identified several common genes and recurrent variants that varied depending on specific epilepsy syndromes. The overall genetic landscape of the Asian population aligns with findings from other populations of varying ethnicities.

Genotypes and phenotypes of DNM1 encephalopathy.

BACKGROUND: Variants in the dynamin-1 (DNM1) gene typically cause synaptopathy, leading to developmental and epileptic encephalopathy (DEE). We aimed to determine the genotypic and phenotypic spectrum of DNM1 encephalopathy beyond DEE. METHODS: Electroclinical phenotyping and genotyping of patients with a DNM1 variant were conducted for patients undergoing next-generation sequencing at our centre, followed by a systematic review. RESULTS: Six patients with heterozygous DNM1 variants were identified in our cohort. Three had a typical DEE phenotype characterised by epileptic spasms, tonic seizures and severe-to-profound intellectual disability with pathogenic variants located in the GTPase or middle domain. The other three patients had atypical phenotypes of milder cognitive impairment and focal epilepsy. Genotypically, two patients with atypical phenotypes had variants located in the GTPase domain, while the third patient had a novel variant (p.M648R) in the linker region between pleckstrin homology and GTPase effector domains. The third patient with an atypical phenotype showed normal development until he developed febrile status epilepticus. Our systematic review on 55 reported cases revealed that those with GTPase or middle domain variants had more severe intellectual disability (p<0.001) and lower functional levels of ambulation (p=0.001) or speech and language (p<0.001) than the rest. CONCLUSION: DNM1-related phenotypes encompass a wide spectrum of epilepsy and neurodevelopmental disorders, with specific variants underlying different phenotypes.

Effects of the ketogenic diet therapy in patients with STXBP1-related encephalopathy.

OBJECTIVE: We aimed to investigate the effects of ketogenic diet (KD) and modified Atkins diet (MAD) in patients with epileptic encephalopathy, caused by the STXBP1 (syntaxin-binding protein 1) gene mutation. METHODS: We retrospectively evaluated the data of patients with STXBP1-related epileptic encephalopathy who were started on either KD or MAD between January 1, 2005, and June 30, 2021, in Severance Children's Hospital. RESULTS: Twelve patients were examined. The median age of seizure onset was 1.5 months [interquartile range (IQR): 0-3] with a median age of dietary therapy initiation at 4.5 months (IQR: 3.0-9.3) and a median diet duration of 6.5 months (IQR: 2.8-13.3). The patients had various epilepsy syndromes: nine (75 %) patients had early infantile developmental and epileptic encephalopathy, two (16.7 %) had infantile epileptic spasms syndrome, and one (8.3 %) had developmental and epileptic encephalopathy. Three patients (25 %) were definite KD responders who achieved seizure freedom within the median of 2 months from KD initiation and remained seizure-free for a median of 36 months (IQR: 29.5-60.0). One patient (8.3 %) was a possible KD responder, seizure-free with KD initiation and steroid therapy while 8 were non-responders (66.7 %). The definite KD responders shared similar clinical characteristics as the rest, except that there were significantly more patients that had seizure onset at ≥ 6 months (p = 0.045) in the definite KD responder group. CONCLUSION: We demonstrated dietary therapy was highly effective for some patients with STXBP1-related epileptic encephalopathy, especially those with later onset.

Geniospasm: A systematic review on natural history, prognosis, and treatment.

BACKGROUND: Geniospasm is a rare and generally benign movement disorder of the chin yet with potentially debilitating complications. Due to its rarity, previous literature was limited to only case reports or series with critical knowledge gap on its natural history, prognosis, and management. We aimed to establish the natural history, prognosis, and treatment for geniospasm. METHODS: A systematic review on case reports or series was performed with literature search on PubMed and Google Scholar, from inception through December 2021. The quality of the reports was assessed with low-quality articles excluded for analyses other than demographics. RESULTS: Forty-one articles were included for demographic analysis (n = 489) while forty articles for other analyses (n = 451). There was only slight male preponderance of this disease in our cohort (Male:Female = 1.2:1) with 98.6% having family history of geniospasm, 68.1% having onset below 1 year of age, 91.4% having emotional triggers of the symptoms, 25.7% having geniospasm in sleep, 100% involving mentalis muscles, 4.9% involving muscles adjacent to mentalis, 55.2% having regular paroxysms (≥1/week, but brief in 56.3% of the cases) and only 11.1% having complications. The paroxysms reduced with age, but complete remission only happened in 9.9%. Females (p = 0.010) and those without geniospasm in sleep (p = 0.048) were associated with good outcome of the disease. Geniospasm was usually refractory to treatment except for regular botulinum toxin injections. CONCLUSION: Generally, geniospasm improved with age but complete remission was rare. Considering our review limitations, our findings should be interpreted with caution. Future studies of higher evidence level are crucial.

Glycemic biomarkers in children with drug-resistant epilepsy on various types of ketogenic diet therapies: A cross-sectional study.

OBJECTIVE: This study was undertaken to determine the hemoglobin A1c (HbA1c) and modified glucose-ketone index (mGKI) in children on different types of ketogenic diet (KD) for treatment of drug-resistant epilepsy, with attempts to evaluate their relationships with components of diet regime and other biomarkers. METHODS: We conducted a cross-sectional study in children with drug resistant epilepsy aged between 6 months and 18 years, who were on various types of KD therapies without any change in regime for at least 3 months. Parental interview, review of medical records, and a single measurement for blood ketone, HbA1c, and plasma carnitine were performed. mGKI was the ratio of an average plasma glucose estimated from HbA1c to blood ß-hydroxybutyrate level. RESULTS: Thirty-four patients were recruited with a median blood ketone of 2.90 mmol·L-1 and median HbA1c of 4.55%. Those on classical KD (cKD) had higher blood ketone (p = .031) and lower HbA1c (p = .010) and mGKI (p = .021) than those receiving modified Atkins diet, although both shared similar percentages of calories from carbohydrate (p = .211). The cKD and medium-chain triglyceride (MCT) KD groups had similar HbA1c (p = .252) and mGKI (p = .510). Blood ketone (p = .045) and the percentage of calories from MCT (p = .037) were the two main independent variables, inversely correlating with HbA1c. Other than plasma acylcarnitine (p = .047), neither blood ketone (p = .188) nor HbA1c (p = .170) could predict seizure reduction reliably. Both plasma acylcarnitine ≥ 6 µmol·L-1 (p = .013) and mGKI ≤ 2.2 (p = .013) were significantly associated with good seizure control. SIGNIFICANCE: HbA1c could potentially be useful for monitoring KD adherence or, indirectly, systemic ketosis in nondiabetic children on KD for drug-resistant epilepsy. Plasma acylcarnitine and mGKI could be important biomarkers in the management of KD therapy.