Electroclinical features of epilepsy in patients with InvDup(15)

What is the role of next generation sequencing in status epilepticus?

Status epilepticus is a life-threatening medical condition which requires immediate diagnosis and treatment. In children, it may be a recurrent manifestation in the context of heterogeneous severe developmental genetic encephalopathies, as well as the first neurological manifestation. Mutations in several genes have been consistently associated with status epilepticus despite none of them can be considered as 'pure' Mendelian status epilepticus gene. Most genetic conditions featuring status epilepticus can be assigned to specific phenotypic subgroups, including cortical dysplasias, inborn errors of metabolism, mitochondrial diseases, or epileptic encephalopathies and childhood syndromes. Next generation sequencing (NGS) has increased the number of genes associated with, and improved the turnaround time for molecular diagnosis of, status epilepticus, allowing more timely and rationale management choices for specific conditions. Next generation sequencing might become part of the standard of care in the near future for a large subset of patients with status epilepticus, especially in early life. At present, trios whole exome sequencing, with a first analysis of point and copy number variants of an in silico panel containing 'status epilepticus' genes might represent best choice as it would allow a rapid screening. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

Behavioral characterization of dup15q syndrome: Toward meaningful endpoints for clinical trials

Duplication of 15q11.2-q13.1 (dup15q syndrome) is one of the most common copy number variations associated with autism spectrum disorders (ASD) and intellectual disability (ID). As with many neurogenetic conditions, accurate behavioral assessment is challenging due to the level of impairment and heterogeneity across individuals. Large-scale phenotyping studies are necessary to inform future clinical trials in this and similar ID syndromes. This study assessed developmental and behavioral characteristics in a large cohort of children with dup15q syndrome, and examined differences based on genetic subtype and epilepsy status. Participants included 62 children (2.5-18 years). Across individuals, there was a wide range of abilities. Although adaptive behavior was strongly associated with cognitive ability, adaptive abilities were higher than cognitive scores. Measures of ASD symptoms were associated with cognitive ability, while parent report of challenging behavior was not. Both genetic subtype and epilepsy were related to degree of impairment across cognitive, language, motor, and adaptive domains. Children with isodicentric duplications and epilepsy showed the greatest impairment, while children with interstitial duplications showed the least. On average, participants with epilepsy experienced seizures over 53% of their lives, and half of children with epilepsy had infantile spasms. Parents of children with isodicentric duplications reported more concerns regarding challenging behaviors. Future trials in ID syndromes should employ a flexible set of assessments, allowing each participant to receive assessments that capture their skills. Multiple sources of information should be considered, and the impact of language and cognitive ability should be taken into consideration when interpreting results.

Possible Phenotypic Consequences of Structural Differences in Idic(15) in a Small Cohort of Patients

Among human supernumerary marker chromosomes, the occurrence of isodicentric form of 15 origin is relatively well known due to its high frequency, both in terms of gene content and associated clinical symptoms. The associated epilepsy and autism are typically more severe than in cases with interstitial 15q duplication, despite copy number gain of approximately the same genomic region. Other mechanisms besides segmental aneuploidy and epigenetic changes may also cause this difference. Among the factors influencing the expression of members of the GABA_A gene cluster, the imprinting effect and copy number differences has been debated. Limited numbers of studies investigate factors influencing the interaction of GABA_A cluster homologues. Five isodicentric (15) patients are reported with heterogeneous symptoms, and structural differences of their isodicentric chromosomes based on array comparative genomic hybridization results. Relations between the structure and the heterogeneous clinical picture are discussed, raising the possibility that the structure of the isodicentric (15), which has an asymmetric breakpoint and consequently a lower copy number segment, would be the basis of the imbalance of the GABA_A homologues. Studies of trans interaction and regulation of GABA_A cluster homologues are needed to resolve this issue, considering copy number differences within the isodicentric chromosome 15.

High-functioning autism spectrum disorder with fluent speech and late-onset epilepsy: an unusual presentation of Inv-Dup (15) syndrome

Many neuropsychiatric phenotypes have been reported in association with rearrangements in the 15q11-q13 region. Clinical presentations can include hypotonia, developmental delay, severe/moderate intellectual disabilities, poor expressive language, difficult to treat epilepsy, and autism spectrum disorders. Here we report an additional case of a girl with inversion duplication on chromosome 15 (Inv-Dup 15) showing a peculiar and milder clinical phenotype, including atypical high-functioning autism disorder, late onset and drug-responsive epilepsy, and a relatively good language development . This report suggests that a diagnosis of Inv-Dup (15) can be suspected during more benign atypical condition with a better outcome than usually reported.

[A clinical and genetic analysis of a child with supernumerary marker chromosome 15-caused mental retardation, intractable epilepsy, and central precocious puberty]

Supernumerary marker chromosome 15 is a rare chromosome abnormality. This paper reports the clinical diagnosis and treatment, as well as genetic defects, of a child with supernumerary marker chromosome 15. The patient was a 9.5-year-old girl who had mental and motor retardation since infancy, breast development at the age of 7 years, and seizures at the age of 8.5 years. Seizures occurred with various features and could not be controlled by a variety of antiepileptic drugs. No abnormalities were found by brain magnetic resonance imaging. Electroencephalogram showed frequent epileptiform discharges. G-banding karyotype analysis, fluorescence in situ hybridization, methylation-specific multiplex ligation-dependent probe amplification, and array comparative genomic hybridization identified a de novo 15q duplication in the patient. The maternal copy number increased in the 15q11-13 region. The form of genome rearrangement was 47,XX,+inv dup(15)(pter to q13:q13 to pter). The increased copy number in the 15q11-13 region is closely related to mental retardation, intractable epilepsy, and central precocious puberty. High-resolution karyotype analysis is recommended for children with unexplained mental retardation and epilepsy.

Electroclinical findings and long-term outcomes in epileptic patients with inv dup (15)

OBJECTIVE

To define the electroclinical phenotype and long-term outcomes in a cohort of patients with inv dup (15) syndrome.

MATERIAL AND METHODS

The electroclinical data of 45 patients (25 males) affected by inv dup (15) and seizures were retrospectively analysed, and long-term follow-up of epilepsy was evaluated.

RESULTS

Epilepsy onset was marked by generalized seizures in 53% of patients, epileptic spasms in 51%, focal seizures in 26%, atypical absences in 11% and epileptic falls in 9%. The epileptic syndromes defined were: generalized epilepsy (26.7%), focal epilepsy (22.3%), epileptic encephalopathy with epileptic spasms as the only seizure type (17.7%) and Lennox-Gastaut syndrome (33.3%). Drug-resistant epilepsy was detected in 55.5% of patients. There was a significant higher prevalence of seizure-free patients in those with seizure onset after the age of 5 years and with focal epilepsy, with respect to those with earlier epilepsy onset because most of these later developed an epileptic encephalopathy (69.2% vs 34.4%; P = .03), usually Lennox-Gastaut Syndrome in type. In fact, among patients with early-onset epilepsy, those presenting with epileptic spasms as the only seizure type associated with classical hypsarrhythmia achieved seizure freedom (P < .001) compared to patients with spasms and other seizure types associated with modified hypsarrhythmia.

CONCLUSIONS

Epilepsy in inv dup (15) leads to a more severe burden of disease. Frequently, these patients show drug resistance, in particular when epilepsy onset is before the age of five and features epileptic encephalopathy.