The Hitchhiker's guide to the child neurologist's genetic evaluation of epilepsy

Refractory Jeavons Syndrome from Birth Symptomatic to PLCB1 Mutation

Jeavons syndrome is a common, often misdiagnosed or overlooked epileptic syndrome presenting with a triad of eyelid myoclonia with or without absence seizures, eye closure-induced EEG paroxysms, and photosensitivity. We present a seven-year-old female who presented with eyelid myoclonia evident since birth with absence seizures and migraines with associated photosensitivity. An EEG with photic stimulation confirmed the diagnosis of Jeavons syndrome. Genetic testing showed a heterozygous mutation in the PLCB1 gene which has been linked to early onset epilepsies and encephalopathic epilepsies. This mutation and her clinical presentation identifies another etiology of Jeavons syndrome and confirms it can begin from birth. Its presence highlights the importance of genetic testing in epileptic patients to better understand the links between genetics and epilepsy syndromes so appropriate treatment can be initiated.

Importance of pedigree in patients with familial epilepsy and intellectual disability

In this study, we prospectively evaluated demographic characteristics, clinical findings and pedigree patterns in 70 patients with familial epilepsy and/or intellectual disability (ID)/global developmental delay (GDD) and/or motor retardation but without specific etiologic diagnosis to determine genetic inheritance patterns by using at least a three-generation pedigree analysis. Mean age of the patients was 6.85 ± 3.93 years and male/female ratio was 1.50. There was consanguinity between the parents of 47 (67.1%) patients. Only epilepsy was diagnosed in 14 patients; only ID/GDD in 22; epilepsy and ID/GDD in 9 and epilepsy and ID/GDD and motor retardation in 25 patients. Genetic inheritance pattern was definitely determined in 60 (85.7%) patients, and most of the patients (61.4%) displayed autosomal recessive inheritance. Based on our findings, we suggest that a three-generation pedigree analysis should be obtained in all patients with familial neurological disorders, including epilepsy, ID/GDD and motor retardation, to optimise counselling, screening and diagnostic testing.

"Simple febrile seizures plus (SFS+)": more than one febrile seizure within 24 hours is usually okay

This study aimed to investigate whether children with recurrent febrile seizures within a 24-hour period need to be worked up differently from children with simple febrile seizures. Inclusion criteria included the following: (i) children with first seizure cluster between 4 months and 3 years of age, (ii) children who had more than one febrile seizure within 24 hours, and (iii) children who returned to baseline between and after each event. Thirty-two patients met the inclusion criteria over a 3-year period. All patients underwent brain CT and/or MRI and EEG. All head CTs were normal. Two children had abnormal MRI findings - both benign: one is thought to represent postictal changes, and the other one is an incidental arachnoid cyst. Of the 4 abnormal EEGs, one showed epileptiform discharges, while the others showed generalized ictal or postictal features. We propose the term "simple febrile seizures plus (SFS+)" to describe children who have more than one seizure within 24 hours but who are otherwise not different in presentation from children with SFS.

mRNA blood expression patterns in new-onset idiopathic pediatric epilepsy

PURPOSE

Determine if blood messenger RNA (mRNA) expression patterns in children with newly diagnosed untreated idiopathic epilepsy are different from those in healthy controls. Determine the differential expression patterns between epilepsy patients with generalized onset or partial onset seizures compared to healthy controls.

METHODS

Whole blood was obtained from otherwise healthy pediatric patients with newly diagnosed untreated idiopathic epilepsy along with healthy pediatric controls. mRNA was isolated and hybridized to Affymetrix HGU 133 2.0+ microarrays. Analysis was performed using Genespring. Differentially expressed gene lists resulted from comparison of (1) epilepsy and control groups and (2) seizure type subgroups with controls. Tissue expression and gene ontology analysis was performed using DAVID.

KEY FINDINGS

Thirty-seven epilepsy patients and 28 controls were included. Overall, 575 genes were differentially expressed in subjects with epilepsy compared to controls. The generalized seizure subgroup versus control (GvC) gene list and the partial seizure subgroup versus control (PvC) gene list were different (p < 0.05). Tissue expression analysis identified almost half of the genes in GvC and PvC as brain based. Functional group analysis identified several biologically relevant pathways. In GvC, these included mitochondria and lymphocyte activation. In PvC, we identified apoptosis, inflammatory defense, and cell motion pathways.

SIGNIFICANCE

A unique, biologically meaningful mRNA expression pattern is detectable in whole blood of pediatric subjects with new-onset and untreated epilepsy. This analysis finds many similar pathways to those identified in brain studies examining lesional intractable epilepsy. Blood mRNA expression patterns show promise as a target for biomarker development in pediatric epilepsy.

Genetic evaluation and counseling for epilepsy

The contribution of genetics to both rare and common epilepsies is rapidly being elucidated, and neurologists are routinely considering genetic testing in the work-up of several epilepsy syndromes of both known and unknown cause. Simultaneously, advances in molecular technology foreshadow additional discoveries in epilepsy etiology, implying a greater role than ever before for genetics in the epilepsy clinic. Genetic testing can be valuable not only for diagnosis but also for guiding treatment and for informing reproductive choices. In this Review, we outline the principles of genetic evaluation and counseling, and describe how to interpret genetic test results for epilepsy in the following five common clinical scenarios: Dravet syndrome, infantile spasms, epilepsy with cortical malformation, epilepsy with mental retardation, and idiopathic epilepsy syndromes. We differentiate clinical situations in which genetic testing is of high and low utility, and predict future areas for the application of genetics in epilepsy practice.