22q11.2 Microduplication syndrome and epilepsy with continuous spikes and waves during sleep (CSWS). A case report and review of the literature

Continuous Spike-Waves during Slow Sleep Today: An Update

In the context of childhood epilepsy, the concept of continuous spike-waves during slow sleep (CSWS) includes several childhood-onset heterogeneous conditions that share electroencephalograms (EEGs) characterized by a high frequency of paroxysmal abnormalities during sleep, which have negative effects on the cognitive development and behavior of the child. These negative effects may have the characteristics of a clear regression or of a slowdown in development. Seizures are very often present, but not constantly. The above makes it clear why CSWS have been included in epileptic encephalopathies, in which, by definition, frequent EEG paroxysmal abnormalities have an unfavorable impact on cognitive functions, including socio-communicative skills, causing autistic features, even regardless of the presence of clinically overt seizures. Although several decades have passed since the original descriptions of the electroclinical condition of CSWS, there are still many areas that are little-known and deserve to be further studied, including the EEG diagnostic criteria, the most effective electrophysiological parameter for monitoring the role of the thalamus in CSWS pathogenesis, its long-term evolution, the nosographic location of Landau-Kleffner syndrome, standardized neuropsychological and behavioral assessments, and pharmacological and non-pharmacological therapies.

The genetic landscape of developmental and epileptic encephalopathy with spike-and-wave activation in sleep

OBJECTIVE

Epileptic Encephalopathy / Developmental Epileptic Encephalopathy with spike-and-wave activation in sleep (EE/DEE-SWAS) is defined as an epilepsy syndrome characterized by neurodevelopmental regression temporally related to the emergence of significant activation of spike-wave discharges in EEG during sleep. The availability of genetic testing has made it evident that monogenic and chromosomal abnormalities play an aetiological role in the development of EE/DEE-SWAS. We sought to review the literature to better understand the genetic landscape of EE/DEE-SWAS.

METHODS

In this systematic review, we reviewed cases of EE/DEE-SWAS associated with a genetic aetiology, collecting information related to the underlying aetiology, onset, management, and EEG patterns.

RESULTS

One hundred and seventy-two cases of EE/DEE-SWAS were identified. Genetic causes of note included pathogenic variants in GRIN2A, ZEB2, CNKSR2 and chromosome 17q21.31 deletions, each of which demonstrated unique clinical characteristics, EEG patterns, and age of onset. Factors identified to raise suspicion of a potential genetic aetiology included the presentation of DEE-SWAS and onset of SWAS under the age of five years. Treatment of EE/DEE-SWAS due to genetic causes was diverse, including a combination of anti-seizure medications, steroids, and other clinical strategies, with no clear consensus on a preferred or superior treatment. Data collected was significantly heterogeneous, with a lack of consistent use of neuropsychology testing, EEG patterns, or use of established clinical definitions.

CONCLUSIONS

Uniformity concerning the new definition of EE/DEE-SWAS, guidelines for management and more frequent genetic screening will be needed to guide best practices for the treatment of patients with EE/DEE-SWAS.

Sleep patterns and problems among children with 22q11 deletion syndrome

BACKGROUND

To delineate sleep habits and problems in children with 22q11.2 deletion syndrome (22q11DS).

METHODS

Thirty children, age 1-15 (mean 6.8) years, participated in the study, which was an internet-based anonymous survey of parents of children with 22q11DS administered via the 22q11.2 Foundation. The main outcome was the Childhood Sleep Habits Questionnaire (CSHQ).

RESULTS

Scores on the CSHQ demonstrated clinically significant sleep problems in 29 of the 30 children. When compared with previously reported normative values for typically developing children of the same age, children with 22q11DS had significantly greater sleep problems. Only 30% of children had previously undergone sleep study. While about half of children had tried a medication for sleep, it usually was not felt to be helpful. In contrast, parents reported that behavioral interventions, such as consistent bedtime routine and appropriate sleep environment, were helpful. This is one of the first studies to specifically address sleep problems other than obstructive sleep apnea in children with 22q11DS.

CONCLUSIONS

The findings suggest children with 22q11DS may have a higher risk of experiencing clinical sleep problems, compared to typically developing children. Consideration of additional screening and treatment of sleep disorders in children with 22q11DS is warranted.

Additive Effect of Variably Penetrant 22q11.2 Duplication and Pathogenic Mutations in Autism Spectrum Disorder: To Which Extent Does the Tree Hide the Forest?

The 22q11.2 duplication is a variably penetrant copy number variant (CNV) associated with a broad spectrum of clinical manifestations including autism spectrum disorders (ASD), and epilepsy. Here, we report on pathogenic HUWE1 and KIF1A mutations in two severely affected ASD/ID participants carrying a 22q11.2 duplication. Based on previous studies, this CNV was originally considered as disease-causing. Yet, owing to their clinical severity, the participants were further investigated by next generation sequencing and eventually found to carry pathogenic mutations in HUWE1 and KIF1A respectively. We suggest giving consideration to additive effect of 22q11.2 duplication and pathogenic mutations when clinical presentation is either unusually severe or associated with atypical features. Caution should be exercised when delivering genetic counseling for variably penetrant CNVs, as uncertain penetrance of this CNV may lead to ignore additive pathogenic mutations. Systematic panel or exome sequencing of known ASD genes should be recommended when counseling families of patients carrying variably penetrant CNV.

Electrical status epilepticus in sleep, a constitutive feature of Christianson syndrome?

Christianson syndrome (CS) is a X-linked neurodevelopmental disorder, including severe intellectual disability (ID), progressive microcephaly, ataxia, autistic behaviour (ASD), near absent speech, and epilepsy. Electrical status epilepticus in sleep (ESES) has been reported in two patients. We describe five male patients from three unrelated families with Christianson syndrome caused by a pathogenic nucleotide variation or a copy-number variation involving SLC9A6. ESES was present in three out of the five patients in the critical age window between 4 and 8 years. All patients presented with severe intellectual disability, autistic features, and hyperactivity. Epilepsy onset occurred within the first two years of life. Seizures were of various types. In the two boys with a 20-years follow-up, epilepsy was drug-resistant during childhood, and became less active in early adolescence. Psychomotor regression was noted in two patients presenting with ESES. It was difficult to assess to what extent ESES could have contributed to the pathophysiological process, leading to regression of the already very limited communication skills. The two published case reports and our observation suggests that ESES could be a constitutive feature of Christianson syndrome, as it has already been shown for other Mendelian epileptic disorders, such as GRIN2A and CNKSR2-related developmental epileptic encephalopathies. Sleep EEG should be performed in patients with Christianson syndrome between 4 and 8 years of age. ESES occurring in the context of ID, ASD and severe speech delay, could be helpful to make a diagnosis of CS.

Recurrent reciprocal copy number variants: Roles and rules in neurodevelopmental disorders

Deletions and duplications, called reciprocal CNVs when they occur at the same locus, are implicated in neurodevelopmental phenotypes ranging from morphological to behavioral. In this article, we propose three models of how differences in gene expression in deletion and duplication genotypes may result in deleterious phenotypes. To explore these models, we use examples of the similarities and differences in clinical phenotypes of five reciprocal CNVs known to cause neurodevelopmental disorders: 1q21.1, 7q11.23, 15q13.3, 16p11.2, and 22q11.2. These models and examples may inform some insights into better understanding of gene-phenotype relationships. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 78: 519-530, 2018.

Analysis of rare copy number variation in absence epilepsies

OBJECTIVE

To identify shared genes and pathways between common absence epilepsy (AE) subtypes (childhood absence epilepsy [CAE], juvenile absence epilepsy [JAE], and unclassified absence epilepsy [UAE]) that may indicate common mechanisms for absence seizure generation and potentially a diagnostic continuum.

METHODS

We used high-density single-nucleotide polymorphism arrays to analyze genome-wide rare copy number variation (CNV) in a cohort of 144 children with AEs (95 CAE, 26 UAE, and 23 JAE).

RESULTS

We identified CNVs that are known risk factors for AE in 4 patients, including 3x 15q11.2 deletion. We also expanded the phenotype at 4 regions more commonly identified in other neurodevelopmental disorders: 1p36.33 duplication, 1q21.1 deletion, 22q11.2 duplication, and Xp22.31 deletion and duplication. Fifteen patients (10.5%) were found to carry rare CNVs that disrupt genes associated with neuronal development and function (8 CAE, 2 JAE, and 5 UAE). Four categories of protein are each disrupted by several CNVs: (1) synaptic vesicle membrane or vesicle endocytosis, (2) synaptic cell adhesion, (3) synapse organization and motility via actin, and (4) gap junctions. CNVs within these categories are shared across the AE subtypes.

CONCLUSIONS

Our results have reinforced the complex and heterogeneous nature of the AEs and their potential for shared genetic mechanisms and have highlighted several pathways that may be important in epileptogenesis of absence seizures.

Genetic mutations associated with status epilepticus

This paper reports the results of a preliminary search of the literature aimed at identifying the genetic mutations reported to be strongly associated with status epilepticus. Genetic mutations were selected for inclusion if status epilepticus was specifically mentioned as a consequence of the mutation in standard genetic databases or in a case report or review article. Mutations in 122 genes were identified. The genetic mutations identified were found in only rare conditions (sometimes vanishingly rare) and mostly in infants and young children with multiple other handicaps. Most of the genetic mutations can be subdivided into those associated with cortical dysplasias, inborn errors of metabolism, mitochondrial disease, or epileptic encephalopathies and childhood syndromes. There are no identified 'pure status epilepticus genes'. The range of genes underpinning status epilepticus differs in many ways from the range of genes underpinning epilepsy, which suggests that the processes underpinning status epilepticus differ from those underpinning epilepsy. It has been frequently postulated that status epilepticus is the result of a failure of 'seizure termination mechanisms', but the wide variety of genes affecting very diverse biochemical pathways identified in this survey makes any unitary cause unlikely. The genetic influences in status epilepticus are likely to involve a wide range of mechanisms, some related to development, some to cerebral energy production, some to diverse altered biochemical pathways, some to transmitter and membrane function, and some to defects in networks or systems. The fact that many of the identified genes are involved with cerebral development suggests that status epilepticus might often be a system or network phenomenon. To date, there are very few genes identified which are associated with adult-onset status epilepticus (except in those with preexisting neurological damage), and this is disappointing as the cause of many adult-onset status epilepticus cases remains obscure. It has been suggested that idiopathic adult-onset status epilepticus might often have an immunological cause but no gene mutations which relate to immunological mechanisms were identified. Overall, the clinical utility of what is currently known about the genetics of status epilepticus is slight and the findings have had little impact on clinical treatment despite what has been a very large investment in money and time. New genetic technologies may result in the identification of further genes, but if the identified genetic defects confer only minor susceptibility, this is unlikely to influence therapy. It is also important to recognize that genetics has social implications in a way that other areas of science do not. This article is part of a Special Issue entitled "Status Epilepticus".

Prenatal Diagnosis of Central Nervous System Anomalies by High-Resolution Chromosomal Microarray Analysis

The aims of this study were to evaluate the contribution of chromosomal microarray analysis (CMA) in the prenatal diagnosis of fetuses with central nervous system (CNS) anomalies but normal chromosomal karyotype. A total of 46 fetuses with CNS anomalies with or without other ultrasound anomalies but normal karyotypes were evaluated by array-based comparative genomic hybridisation (aCGH) or single-nucleotide polymorphism (SNP) array. The result showed that CNVs were detected in 17 (37.0%) fetuses. Of these, CNVs identified in 5 (5/46, 10.9%) fetuses were considered to be likely pathogenic, and CNVs detected in 3 (3/46, 6.5%) fetuses were defined as being of uncertain clinical significance. Fetuses with CNS malformations plus other ultrasound anomalies had a higher rate of pathogenic CNVs than those with isolated CNS anomalies (13.6% versus 8.3%), but there was no significant difference (Fisher's exact test, P > 0.05). Pathogenic CNVs were detected most frequently in fetuses with Dandy-Walker syndrome (2/6, 33.3%) when compared with other types of neural malformations, and holoprosencephaly (2/7, 28.6%) ranked the second. CMA is valuable in prenatal genetic diagnosis of fetuses with CNS anomalies. It should be considered as part of prenatal diagnosis in fetuses with CNS malformations and normal karyotypes.

Continuous spike and wave in slow-wave sleep in a patient with Rett syndrome and in a patient with Lhermitte-Duclos syndrome and neurofibromatosis 1

Continuous spike and wave in slow-wave sleep (CSWS) is an electroencephalographic (EEG) pattern characterized by generalized spike-wave discharges occurring for at least 85% of non-rapid eye movement (non-REM) sleep, with marked attenuation during rapid eye movement (REM) sleep. It has been described in a large number of structural and nonstructural neurologic conditions and is associated with epilepsy, behavioral disturbances, and severe neuropsychiatric impairment. We describe continuous spike and wave in slow-wave sleep in 2 patients (one with Rett syndrome and the other with Lhermitte-Duclos syndrome). To our knowledge, continuous spike and wave in slow-wave sleep has not been previously described in these conditions.

Genetic forms of epilepsies and other paroxysmal disorders

Genetic mechanisms explain the pathophysiology of many forms of epilepsy and other paroxysmal disorders, such as alternating hemiplegia of childhood, familial hemiplegic migraine, and paroxysmal dyskinesias. Epilepsy is a key feature of well-defined genetic syndromes including tuberous sclerosis complex, Rett syndrome, Angelman syndrome, and others. There is an increasing number of single-gene causes or susceptibility factors associated with several epilepsy syndromes, including the early-onset epileptic encephalopathies, benign neonatal/infantile seizures, progressive myoclonus epilepsies, genetic generalized and benign focal epilepsies, epileptic aphasias, and familial focal epilepsies. Molecular mechanisms are diverse, and a single gene can be associated with a broad range of phenotypes. Additional features, such as dysmorphisms, head size, movement disorders, and family history may provide clues to a genetic diagnosis. Genetic testing can impact medical care and counseling. We discuss genetic mechanisms of epilepsy and other paroxysmal disorders, tools and indications for genetic testing, known genotype-phenotype associations, the importance of genetic counseling, and a look toward the future of epilepsy genetics.

16p11.2 600 kb Duplications confer risk for typical and atypical Rolandic epilepsy

Rolandic epilepsy (RE) is the most common idiopathic focal childhood epilepsy. Its molecular basis is largely unknown and a complex genetic etiology is assumed in the majority of affected individuals. The present study tested whether six large recurrent copy number variants at 1q21, 15q11.2, 15q13.3, 16p11.2, 16p13.11 and 22q11.2 previously associated with neurodevelopmental disorders also increase risk of RE. Our association analyses revealed a significant excess of the 600 kb genomic duplication at the 16p11.2 locus (chr16: 29.5-30.1 Mb) in 393 unrelated patients with typical (n = 339) and atypical (ARE; n = 54) RE compared with the prevalence in 65,046 European population controls (5/393 cases versus 32/65,046 controls; Fisher's exact test P = 2.83 × 10(-6), odds ratio = 26.2, 95% confidence interval: 7.9-68.2). In contrast, the 16p11.2 duplication was not detected in 1738 European epilepsy patients with either temporal lobe epilepsy (n = 330) and genetic generalized epilepsies (n = 1408), suggesting a selective enrichment of the 16p11.2 duplication in idiopathic focal childhood epilepsies (Fisher's exact test P = 2.1 × 10(-4)). In a subsequent screen among children carrying the 16p11.2 600 kb rearrangement we identified three patients with RE-spectrum epilepsies in 117 duplication carriers (2.6%) but none in 202 carriers of the reciprocal deletion. Our results suggest that the 16p11.2 duplication represents a significant genetic risk factor for typical and atypical RE.