Long-term treatment with ganaxolone for seizures associated with cyclin-dependent kinase-like 5 deficiency disorder: Two-year open-label extension follow-up.

OBJECTIVE: In the placebo-controlled, double-blind phase of the Marigold study (NCT03572933), ganaxolone significantly reduced major motor seizure frequency (MMSF) in patients with cyclin-dependent kinase-like 5 deficiency disorder (CDD). We report 2-year safety and clinical outcomes data from the open-label extension (OLE) phase of Marigold. METHODS: Patients with CDD who completed the double-blind phase were eligible to continue in the OLE. Efficacy assessments included MMSF reduction from prerandomization baseline, responder rates, and Clinical Global Impression-Improvement scores, including assessment of seizure intensity and duration (CGI-CSID). Safety assessments included treatment-emergent adverse events (TEAEs) and TEAEs leading to discontinuation. RESULTS: Of 101 patients who enrolled in Marigold, 88 (87.1%) entered the OLE (median age = 5 years, 79.5% female). Median 28-day MMSF at baseline was 50.6. At 2 years in the OLE (months 22-24), MMSF was reduced by a median of 48.2% (n = 50); when missing data were imputed, median reduction in MMSF was 43.8% using a mixed effects model and 27.4% using a last observation carried forward model. During months 22-24, 23 of 50 (46.0%) patients experienced reductions in MMSF of ≥50%; 12 of 50 (24.0%) patients experienced MMSF reductions of ≥75%. During months 22-24, 40 of 49 (81.6%) patients were rated by caregivers as having improvement in seizure-related outcomes based on CGI-CSID scores. Thirty-seven patients discontinued ganaxolone due to lack of efficacy (n = 13), withdrawal by caregiver (n = 12), adverse event (n = 10), physician decision (n = 1), or death (n = 1; unrelated to study drug). The most common treatment-related TEAEs were somnolence (17.0%), seizure (11.4%), and decreased appetite (5.7%). Patients reported serious TEAEs (n = 28, 31.8%); those reported in ≥3% of patients were seizure (n = 6), pneumonia (n = 5), acute respiratory failure (n = 3), aspiration pneumonia (n = 3), and dehydration (n = 3). SIGNIFICANCE: Sustained reductions in MMSF at 2 years in the OLE support the efficacy of ganaxolone in seizures associated with CDD. Safety findings in the OLE were consistent with the double-blind phase.

CDKL5 deficiency disorder and other infantile-onset genetic epilepsies.

AIM: To differentiate phenotypic features of individuals with CDKL5 deficiency disorder (CDD) from those of individuals with other infantile-onset epilepsies. METHOD: We performed a retrospective cohort study and ascertained individuals with CDD and comparison individuals with infantile-onset epilepsy who had epilepsy gene panel testing. We reviewed records, updated variant classifications, and compared phenotypic features. Wilcoxon rank-sum tests and χ2 or Fisher's exact tests were performed for between-cohort comparisons. RESULTS: We identified 137 individuals with CDD (110 females, 80.3%; median age at last follow-up 3 year 11 months) and 313 individuals with infantile-onset epilepsies (156 females, 49.8%; median age at last follow-up 5 years 2 months; 35% with genetic diagnosis). Features reported significantly more frequently in the CDD group than in the comparison cohort included developmental and epileptic encephalopathy (81% vs 66%), treatment-resistant epilepsy (95% vs 71%), sequential seizures (46% vs 6%), epileptic spasms (66% vs 42%, with hypsarrhythmia in 30% vs 48%), regression (52% vs 29%), evolution to Lennox-Gastaut syndrome (23% vs 5%), diffuse hypotonia (72% vs 36%), stereotypies (69% vs 11%), paroxysmal movement disorders (29% vs 17%), cerebral visual impairment (94% vs 28%), and failure to thrive (38% vs 22%). INTERPRETATION: CDD, compared with other suspected or confirmed genetic epilepsies presenting in the first year of life, is more often characterized by a combination of treatment-resistant epilepsy, developmental and epileptic encephalopathy, sequential seizures, spasms without hypsarrhythmia, diffuse hypotonia, paroxysmal movement disorders, cerebral visual impairment, and failure to thrive. Defining core phenotypic characteristics will improve precision diagnosis and treatment.

Ezogabine impacts seizures and development in patients with KCNQ2 developmental and epileptic encephalopathy.

Genetic variants in KCNQ2 are associated with a range of epilepsies, from self- limited (familial) neonatal-infantile epilepsy to developmental and epileptic encephalopathy (DEE). We retrospectively reviewed clinical data from eight patients with KCNQ2-related DEE who were treated with ezogabine. Treatment was initiated at a median age of 8 months (range, 7 weeks to 2.5 years) and continued for a median of 2.6 years (range, 7 months to 4.5 years). Five individuals had daily seizures at baseline and experienced at least 50% seizure reduction with treatment, sustained in four. One individual with two to four yearly seizures improved to rare events. Two individuals were seizure-free; treatment targeted cognition and development. Developmental improvements were reported in all eight patients. Weaning of ezogabine was associated with increased seizure frequency (N = 4), agitation and irritability (N = 2), poor sleep (N = 1), and developmental regression (N = 2). These data suggest that treatment with ezogabine is effective at reducing seizure burden and is associated with improved development. Minimal side effects were observed. Weaning was associated with increased seizures and behavioral disturbances in a subset. An approach targeting potassium channel dysfunction with ezogabine is warranted in patients with KCNQ2-related DEE.

Epileptic spasms in CDKL5 deficiency disorder: Delayed treatment and poor response to first-line therapies.

OBJECTIVE: We aimed to assess the treatment response of infantile-onset epileptic spasms (ES) in CDKL5 deficiency disorder (CDD) vs other etiologies. METHODS: We evaluated patients with ES from the CDKL5 Centers of Excellence and the National Infantile Spasms Consortium (NISC), with onset from 2 months to 2 years, treated with adrenocorticotropic hormone (ACTH), oral corticosteroids, vigabatrin, and/or the ketogenic diet. We excluded children with tuberous sclerosis complex, trisomy 21, or unknown etiology with normal development because of known differential treatment responses. We compared the two cohorts for time to treatment and ES remission at 14 days and 3 months. RESULTS: We evaluated 59 individuals with CDD (79% female, median ES onset 6 months) and 232 individuals from the NISC database (46% female, median onset 7 months). In the CDD cohort, seizures prior to ES were common (88%), and hypsarrhythmia and its variants were present at ES onset in 34%. Initial treatment with ACTH, oral corticosteroids, or vigabatrin started within 1 month of ES onset in 27 of 59 (46%) of the CDD cohort and 182 of 232 (78%) of the NISC cohort (p < .0001). Fourteen-day clinical remission of ES was lower for the CDD group (26%, 7/27) than for the NISC cohort (58%, 106/182, p = .0002). Sustained ES remission at 3 months occurred in 1 of 27 (4%) of CDD patients vs 96 of 182 (53%) of the NISC cohort (p < .0001). Comparable results were observed with longer lead time (≥1 month) or prior treatment. Ketogenic diet, used within 3 months of ES onset, resulted in ES remission at 1 month, sustained at 3 months, in at least 2 of 13 (15%) individuals with CDD. SIGNIFICANCE: Compared to the broad group of infants with ES, children with ES in the setting of CDD often experience longer lead time to treatment and respond poorly to standard treatments. Development of alternative treatments for ES in CDD is needed.

Characterization of the GABRB2-Associated Neurodevelopmental Disorders.

OBJECTIVE: We aimed to characterize the phenotypic spectrum and functional consequences associated with variants in the gene GABRB2, coding for the γ-aminobutyric acid type A (GABAA ) receptor subunit ß2. METHODS: We recruited and systematically evaluated 25 individuals with variants in GABRB2, 17 of whom are newly described and 8 previously reported with additional clinical data. Functional analysis was performed using a Xenopus laevis oocyte model system. RESULTS: Our cohort of 25 individuals from 22 families with variants in GABRB2 demonstrated a range of epilepsy phenotypes from genetic generalized epilepsy to developmental and epileptic encephalopathy. Fifty-eight percent of individuals had pharmacoresistant epilepsy; response to medications targeting the GABAergic pathway was inconsistent. Developmental disability (present in 84%) ranged from mild intellectual disability to severe global disability; movement disorders (present in 44%) included choreoathetosis, dystonia, and ataxia. Disease-associated variants cluster in the extracellular N-terminus and transmembrane domains 1-3, with more severe phenotypes seen in association with variants in transmembrane domains 1 and 2 and the allosteric binding site between transmembrane domains 2 and 3. Functional analysis of 4 variants in transmembrane domains 1 or 2 (p.Ile246Thr, p.Pro252Leu, p.Ile288Ser, p.Val282Ala) revealed strongly reduced amplitudes of GABA-evoked anionic currents. INTERPRETATION: GABRB2-related epilepsy ranges broadly in severity from genetic generalized epilepsy to developmental and epileptic encephalopathies. Developmental disability and movement disorder are key features. The phenotypic spectrum is comparable to other GABAA receptor-encoding genes. Phenotypic severity varies by protein domain. Experimental evidence supports loss of GABAergic inhibition as the mechanism underlying GABRB2-associated neurodevelopmental disorders. ANN NEUROL 2021;89:573-586.

Wide range of phenotypic severity in individuals with late truncations unique to the predominant CDKL5 transcript in the brain.

Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is caused by heterozygous or hemizygous variants in CDKL5 and is characterized by refractory epilepsy, cognitive and motor impairments, and cerebral visual impairment. CDKL5 has multiple transcripts, of which the longest transcripts, NM_003159 and NM_001037343, have been used historically in clinical laboratory testing. However, the transcript NM_001323289 is the most highly expressed in brain and contains 170 nucleotides at the 3' end of its last exon that are noncoding in other transcripts. Two truncating variants in this region have been reported in association with a CDD phenotype. To clarify the significance and range of phenotypes associated with late truncating variants in this region of the predominant transcript in the brain, we report detailed information on two individuals, updated clinical information on a third individual, and a summary of published and unpublished individuals reported in ClinVar. The two new individuals (one male and one female) each had a relatively mild clinical presentation including periods of pharmaco-responsive epilepsy, independent walking and limited purposeful communication skills. A previously reported male continued to have a severe phenotype. Overall, variants in this region demonstrate a range of clinical severity consistent with reports in CDD but with the potential for milder presentation.

A Recurrent De Novo PACS2 Heterozygous Missense Variant Causes Neonatal-Onset Developmental Epileptic Encephalopathy, Facial Dysmorphism, and Cerebellar Dysgenesis.

Developmental and epileptic encephalopathies (DEEs) represent a large clinical and genetic heterogeneous group of neurodevelopmental diseases. The identification of pathogenic genetic variants in DEEs remains crucial for deciphering this complex group and for accurately caring for affected individuals (clinical diagnosis, genetic counseling, impacting medical, precision therapy, clinical trials, etc.). Whole-exome sequencing and intensive data sharing identified a recurrent de novo PACS2 heterozygous missense variant in 14 unrelated individuals. Their phenotype was characterized by epilepsy, global developmental delay with or without autism, common cerebellar dysgenesis, and facial dysmorphism. Mixed focal and generalized epilepsy occurred in the neonatal period, controlled with difficulty in the first year, but many improved in early childhood. PACS2 is an important PACS1 paralog and encodes a multifunctional sorting protein involved in nuclear gene expression and pathway traffic regulation. Both proteins harbor cargo(furin)-binding regions (FBRs) that bind cargo proteins, sorting adaptors, and cellular kinase. Compared to the defined PACS1 recurrent variant series, individuals with PACS2 variant have more consistently neonatal/early-infantile-onset epilepsy that can be challenging to control. Cerebellar abnormalities may be similar but PACS2 individuals exhibit a pattern of clear dysgenesis ranging from mild to severe. Functional studies demonstrated that the PACS2 recurrent variant reduces the ability of the predicted autoregulatory domain to modulate the interaction between the PACS2 FBR and client proteins, which may disturb cellular function. These findings support the causality of this recurrent de novo PACS2 heterozygous missense in DEEs with facial dysmorphim and cerebellar dysgenesis.

Cerebral visual impairment in CDKL5 deficiency disorder: vision as an outcome measure.

AIM: To characterize the neuro-ophthalmological phenotype of cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) and assess visual acuity as a reproducible, quantitative outcome measure. METHOD: We retrospectively analyzed clinical data from patients with CDD. Complete neuro-ophthalmological assessments, including visual acuity, were evaluated. RESULTS: Of 26 patients (22 females, four males; median age 4y, interquartile range 2y 1mo-7y 10mo), cerebral visual impairment (CVI), defined as visual dysfunction in the absence of ocular or anterior visual pathway abnormalities, was diagnosed in all those over 2 years of age. Ophthalmological examinations revealed nystagmus in 10 patients and strabismus in 24 patients. Visual acuity was measured in 24 patients, by preferential looking in all and by sweep visual evoked potential in 13. Visual acuities were lower than age expectations and demonstrated improvement in the first 3 years. Adjusting for age and sex, average preferential looking visual acuity after 2 years of age was higher in patients with intact mobility than in those who were non-mobile. INTERPRETATION: CVI was observed in patients with CDD. Visual acuity improved over time and correlated with mobility. Visual acuity, as a quantifiable measure of visual function, should be considered as an outcome measure in pre-clinical and clinical studies for CDD. What this paper adds Cerebral visual impairment is highly prevalent in cyclin-dependent kinase-like 5 deficiency disorder (CDD). Visual acuity is a measurable quantitative outcome measure in CDD. Visual acuity in CDD correlates with gross motor ability.

Genetic diagnoses in epilepsy: The impact of dynamic exome analysis in a pediatric cohort.

OBJECTIVE: We evaluated the yield of systematic analysis and/or reanalysis of whole exome sequencing (WES) data from a cohort of well-phenotyped pediatric patients with epilepsy and suspected but previously undetermined genetic etiology. METHODS: We identified and phenotyped 125 participants with pediatric epilepsy. Etiology was unexplained at the time of enrollment despite clinical testing, which included chromosomal microarray (57 patients), epilepsy gene panel (n = 48), both (n = 28), or WES (n = 8). Clinical epilepsy diagnoses included developmental and epileptic encephalopathy (DEE), febrile infection-related epilepsy syndrome, Rasmussen encephalitis, and other focal and generalized epilepsies. We analyzed WES data and compared the yield in participants with and without prior clinical genetic testing. RESULTS: Overall, we identified pathogenic or likely pathogenic variants in 40% (50/125) of our study participants. Nine patients with DEE had genetic variants in recently published genes that had not been recognized as epilepsy-related at the time of clinical testing (FGF12, GABBR1, GABBR2, ITPA, KAT6A, PTPN23, RHOBTB2, SATB2), and eight patients had genetic variants in candidate epilepsy genes (CAMTA1, FAT3, GABRA6, HUWE1, PTCHD1). Ninety participants had concomitant or subsequent clinical genetic testing, which was ultimately explanatory for 26% (23/90). Of the 67 participants whose molecular diagnoses were "unsolved" through clinical genetic testing, we identified pathogenic or likely pathogenic variants in 17 (25%). SIGNIFICANCE: Our data argue for early consideration of WES with iterative reanalysis for patients with epilepsy, particularly those with DEE or epilepsy with intellectual disability. Rigorous analysis of WES data of well-phenotyped patients with epilepsy leads to a broader understanding of gene-specific phenotypic spectra as well as candidate disease gene identification. We illustrate the dynamic nature of genetic diagnosis over time, with analysis and in some cases reanalysis of exome data leading to the identification of disease-associated variants among participants with previously nondiagnostic results from a variety of clinical testing strategies.

Biological concepts in human sodium channel epilepsies and their relevance in clinical practice.

OBJECTIVE: Voltage-gated sodium channels (SCNs) share similar amino acid sequence, structure, and function. Genetic variants in the four human brain-expressed SCN genes SCN1A/2A/3A/8A have been associated with heterogeneous epilepsy phenotypes and neurodevelopmental disorders. To better understand the biology of seizure susceptibility in SCN-related epilepsies, our aim was to determine similarities and differences between sodium channel disorders, allowing us to develop a broader perspective on precision treatment than on an individual gene level alone. METHODS: We analyzed genotype-phenotype correlations in large SCN-patient cohorts and applied variant constraint analysis to identify severe sodium channel disease. We examined temporal patterns of human SCN expression and correlated functional data from in vitro studies with clinical phenotypes across different sodium channel disorders. RESULTS: Comparing 865 epilepsy patients (504 SCN1A, 140 SCN2A, 171 SCN8A, four SCN3A, 46 copy number variation [CNV] cases) and analysis of 114 functional studies allowed us to identify common patterns of presentation. All four epilepsy-associated SCN genes demonstrated significant constraint in both protein truncating and missense variation when compared to other SCN genes. We observed that age at seizure onset is related to SCN gene expression over time. Individuals with gain-of-function SCN2A/3A/8A missense variants or CNV duplications share similar characteristics, most frequently present with early onset epilepsy (<3 months), and demonstrate good response to sodium channel blockers (SCBs). Direct comparison of corresponding SCN variants across different SCN subtypes illustrates that the functional effects of variants in corresponding channel locations are similar; however, their clinical manifestation differs, depending on their role in different types of neurons in which they are expressed. SIGNIFICANCE: Variant function and location within one channel can serve as a surrogate for variant effects across related sodium channels. Taking a broader view on precision treatment suggests that in those patients with a suspected underlying genetic epilepsy presenting with neonatal or early onset seizures (<3 months), SCBs should be considered.

CDKL5 deficiency disorder: Relationship between genotype, epilepsy, cortical visual impairment, and development.

OBJECTIVE: The cyclin-dependent kinase like 5 (CDKL5) gene is a known cause of early onset developmental and epileptic encephalopathy, also known as CDKL5 deficiency disorder (CDD). We sought to (1) provide a description of seizure types in patients with CDD, (2) provide an assessment of the frequency of seizure-free periods and cortical visual impairment (CVI), (3) correlate these features with genotype and gender, and (4) correlate these features with developmental milestones. METHODS: This is a cohort study of patients with CDD. Phenotypic features were explored and correlated with gene variant grouping and gender. A developmental score was created based on achieving seven primary milestones. Phenotypic variables were correlated with the developmental score to explore markers of better developmental outcomes. Multivariate linear regression was used to account for age at last visit. RESULTS: Ninety-two patients with CDD were seen during the enrollment period. Eighteen were male (19%); median age at last visit was 5 years (interquartile range = 2.0-11.0). Eighty-one percent of patients developed epileptic spasms, but only 47% of those also had hypsarrhythmia. Previously described hypermotor-tonic-spasms sequence was seen in only 24% of patients, but 56% of patients had seizures with multiple phases (often tonic and spasms). Forty-three percent of patients experienced a seizure-free period ranging from 1 to >12 months, but only 6% were still seizure-free at the last visit. CVI was present in 75% of all CDD patients. None of these features was associated with genotype group or gender. CVI was correlated with reduced milestone achievement after adjusting for age at last visit and a history of hypsarrhythmia. SIGNIFICANCE: The most common seizure types in CDD are epileptic spasms (often without hypsarrhythmia) and tonic seizures that may cluster together. CVI is a common feature in CDD and is correlated with achieving fewer milestones.

Characterization of a novel variant in siblings with Asparagine Synthetase Deficiency.

Asparagine Synthetase Deficiency (ASD) is a recently described inborn error of metabolism caused by bi-allelic pathogenic variants in the asparagine synthetase (ASNS) gene. ASD typically presents congenitally with microcephaly and severe, often medically refractory, epilepsy. Development is generally severely affected at birth. Tone is abnormal with axial hypotonia and progressive appendicular spasticity. Hyperekplexia has been reported. Neuroimaging typically demonstrates gyral simplification, abnormal myelination, and progressive cerebral atrophy. The present report describes two siblings from consanguineous parents with a homozygous Arg49Gln variant associated with a milder form of ASD that is characterized by later onset of symptoms. Both siblings had a period of normal development before onset of seizures, and development regression. Primary fibroblast studies of the siblings and their parents document that homozygosity for Arg49Gln blocks cell growth in the absence of extracellular asparagine. Functional studies with these cells suggest no impact of the Arg49Gln variant on basal ASNS mRNA or protein levels, nor on regulation of the gene itself. Molecular modelling of the ASNS protein structure indicates that the Arg49Gln variant lies near the substrate binding site for glutamine. Collectively, the results suggest that the Arg49Gln variant affects the enzymatic function of ASNS. The clinical, cellular, and molecular observations from these siblings expand the known phenotypic spectrum of ASD.

Genetics and genotype-phenotype correlations in early onset epileptic encephalopathy with burst suppression.

OBJECTIVE: We sought to identify genetic causes of early onset epileptic encephalopathies with burst suppression (Ohtahara syndrome and early myoclonic encephalopathy) and evaluate genotype-phenotype correlations. METHODS: We enrolled 33 patients with a referral diagnosis of Ohtahara syndrome or early myoclonic encephalopathy without malformations of cortical development. We performed detailed phenotypic assessment including seizure presentation, electroencephalography, and magnetic resonance imaging. We confirmed burst suppression in 28 of 33 patients. Research-based exome sequencing was performed for patients without a previously identified molecular diagnosis from clinical evaluation or a research-based epilepsy gene panel. RESULTS: In 17 of 28 (61%) patients with confirmed early burst suppression, we identified variants predicted to be pathogenic in KCNQ2 (n = 10), STXBP1 (n = 2), SCN2A (n = 2), PNPO (n = 1), PIGA (n = 1), and SEPSECS (n = 1). In 3 of 5 (60%) patients without confirmed early burst suppression, we identified variants predicted to be pathogenic in STXBP1 (n = 2) and SCN2A (n = 1). The patient with the homozygous PNPO variant had a low cerebrospinal fluid pyridoxal-5-phosphate level. Otherwise, no early laboratory or clinical features distinguished the cases associated with pathogenic variants in specific genes from each other or from those with no prior genetic cause identified. INTERPRETATION: We characterize the genetic landscape of epileptic encephalopathy with burst suppression, without brain malformations, and demonstrate feasibility of genetic diagnosis with clinically available testing in >60% of our cohort, with KCNQ2 implicated in one-third. This electroclinical syndrome is associated with pathogenic variation in SEPSECS. Ann Neurol 2017;81:419-429.

A randomized controlled trial of levodopa in patients with Angelman syndrome.

Treatment for Angelman syndrome (AS) is currently limited to symptomatic interventions. A mouse model of AS has reduced calcium/calmodulin-dependent kinase II activity due to excessive phosphorylation of specific threonine residues, leading to diminished long-term potentiation. In a rat model of Parkinson disease, levodopa reduced phosphorylation of various proteins, including calcium/calmodulin-dependent kinase II. Further studies demonstrated that AS mice treated with levodopa performed better on rotarod testing than untreated AS mice. We conducted a multi-center double-blind randomized placebo-controlled 1-year trial of levodopa / carbidopa with either 10 or 15 mg/kg/day of levodopa in children with AS. The outcome of this intervention was assessed using either the Bayley Scales of Infant Development or the Mullen Scales of Early Learning, as well as the Vineland Adaptive Behavior Scales, and the Aberrant Behavior Checklist. Of the 78 participants enrolled, 67 participants received study medication (33 on levodopa, 34 on placebo), and 55 participants (29 on levodopa, 26 on placebo) completed the 1-year study. There were no clinically or statistically significant changes in any of the outcome measures over a 1-year period comparing the levodopa and placebo groups. The number of adverse events reported, including the more serious adverse events, was similar in both groups, but none were related to treatment with levodopa. Our data demonstrate that levodopa is well-tolerated by children with AS. However, in the doses used in this study, it failed to improve their neurodevelopment or behavioral outcome.

Use of the ketogenic diet to manage refractory epilepsy in CDKL5 disorder: Experience of >100 patients.

OBJECTIVE: Pathogenic variants involving the CDKL5 gene result in a severe epileptic encephalopathy, often later presenting with features similar to Rett syndrome. Cardinal features of epilepsy in the CDKL5 disorder include early onset at a median age of 6 weeks and poor response to antiepileptic drugs. The ketogenic diet (KD) was first introduced in the 1920s as a treatment option for refractory epilepsy in children. This study investigated use of the KD in the CDKL5 disorder and its influences on seizures. METHODS: The International CDKL5 Disorder Database, established in 2012, collects information on individuals with the CDKL5 disorder. Families have provided information regarding seizure characteristics, use, and side effects of the KD treatment. Descriptive statistics and time to event analyses were performed. Clinical vignettes were also provided on patients attending Boston Children's Hospital. RESULTS: Data regarding KD use were available for 204 individuals with a pathogenic CDKL5 variant. Median age of inclusion in the database was 4.8 years (range = 0.3-33.9 years), with median age of 6 weeks (range = 1 day-65 weeks) at seizure onset. History of KD use was reported for 51% (104 of 204) of individuals, with a median duration of use of 17 months (95% confidence interval = 9-24). Changes in seizure activity after commencing KD were reported for two-thirds (69 of 104), with improvements in 88% (61 of 69). Nearly one-third (31.7%) experienced side effects during the diet. At ascertainment, only one-third (32%) remained on the diet, with lack of long-term efficacy as the main reason for diet cessation (51%, 36 of 70). SIGNIFICANCE: Benefits of KD in the CDKL5 disorder are in keeping with previous trials on refractory epilepsies. However, poor long-term efficacy remains as a significant barrier. In view of its side effect profile, KD administration should be supervised by a pediatric neurologist and specialist dietician.

BRAT1 mutations present with a spectrum of clinical severity.

Mutations in BRAT1, encoding BRCA1-associated ATM activator 1, are associated with a severe phenotype known as rigidity and multifocal seizure syndrome, lethal neonatal (RMFSL; OMIM # 614498), characterized by intractable seizures, hypertonia, autonomic instability, and early death. We expand the phenotypic spectrum of BRAT1 related disorders by reporting on four individuals with various BRAT1 mutations resulting in clinical severity that is either mild or moderate compared to the severe phenotype seen in RMFSL. Representing mild severity are three individuals (Patients 1-3), who are girls (including two sisters, Patients 1-2) between 4 and 10 years old, with subtle dysmorphisms, intellectual disability, ataxia or dyspraxia, and cerebellar atrophy on brain MRI; additionally, Patient 3 has well-controlled epilepsy and microcephaly. Representing moderate severity is a 15-month-old boy (Patient 4) with severe global developmental delay, refractory epilepsy, microcephaly, spasticity, hyperkinetic movements, dysautonomia, and chronic lung disease. In contrast to RMFSL, his seizure onset occurred later at 4 months of age, and he is still alive. All four of the individuals have compound heterozygous BRAT1 mutations discovered via whole exome sequencing: c.638dupA (p.Val214Glyfs*189); c.803+1G>C (splice site mutation) in Patients 1-2; c.638dupA (p.Val214Glyfs*189); c.419T>C (p.Leu140Pro) in Patient 3; and c.171delG (p.Glu57Aspfs*7); c.419T>C (p.Leu140Pro) in Patient 4. Only the c.638dupA (p.Val214Glyfs*189) mutation has been previously reported in association with RMFSL. These patients illustrate that, compared with RMFSL, BRAT1 mutations can result in both moderately severe presentations evident by later-onset epilepsy and survival past infancy, as well as milder presentations that include intellectual disability, ataxia/dyspraxia, and cerebellar atrophy. © 2016 Wiley Periodicals, Inc.

Mutations in epilepsy and intellectual disability genes in patients with features of Rett syndrome.

Rett syndrome and neurodevelopmental disorders with features overlapping this syndrome frequently remain unexplained in patients without clinically identified MECP2 mutations. We recruited a cohort of 11 patients with features of Rett syndrome and negative initial clinical testing for mutations in MECP2. We analyzed their phenotypes to determine whether patients met formal criteria for Rett syndrome, reviewed repeat clinical genetic testing, and performed exome sequencing of the probands. Using 2010 diagnostic criteria, three patients had classical Rett syndrome, including two for whom repeat MECP2 gene testing had identified mutations. In a patient with neonatal onset epilepsy with atypical Rett syndrome, we identified a frameshift deletion in STXBP1. Among seven patients with features of Rett syndrome not fulfilling formal diagnostic criteria, four had suspected pathogenic mutations, one each in MECP2, FOXG1, SCN8A, and IQSEC2. MECP2 mutations are highly correlated with classical Rett syndrome. Genes associated with atypical Rett syndrome, epilepsy, or intellectual disability should be considered in patients with features overlapping with Rett syndrome and negative MECP2 testing. While most of the identified mutations were apparently de novo, the SCN8A variant was inherited from an unaffected parent mosaic for the mutation, which is important to note for counseling regarding recurrence risks.

The genetics of the epilepsies.

While genetic causes of epilepsy have been hypothesized from the time of Hippocrates, the advent of new genetic technologies has played a tremendous role in elucidating a growing number of specific genetic causes for the epilepsies. This progress has contributed vastly to our recognition of the epilepsies as a diverse group of disorders, the genetic mechanisms of which are heterogeneous. Genotype-phenotype correlation, however, is not always clear. Nonetheless, the developments in genetic diagnosis raise the promise of a future of personalized medicine. Multiple genetic tests are now available, but there is no one test for all possible genetic mutations, and the balance between cost and benefit must be weighed. A genetic diagnosis, however, can provide valuable information regarding comorbidities, prognosis, and even treatment, as well as allow for genetic counseling. In this review, we will discuss the genetic mechanisms of the epilepsies as well as the specifics of particular genetic epilepsy syndromes. We will include an overview of the available genetic testing methods, the application of clinical knowledge into the selection of genetic testing, genotype-phenotype correlations of epileptic disorders, and therapeutic advances as well as a discussion of the importance of genetic counseling.