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1.  Burden Analysis of Rare Microdeletions Suggests a Strong Impact of Neurodevelopmental Genes in Genetic Generalised Epilepsies 
PLoS Genetics  2015;11(5):e1005226.
Genetic generalised epilepsy (GGE) is the most common form of genetic epilepsy, accounting for 20% of all epilepsies. Genomic copy number variations (CNVs) constitute important genetic risk factors of common GGE syndromes. In our present genome-wide burden analysis, large (≥ 400 kb) and rare (< 1%) autosomal microdeletions with high calling confidence (≥ 200 markers) were assessed by the Affymetrix SNP 6.0 array in European case-control cohorts of 1,366 GGE patients and 5,234 ancestry-matched controls. We aimed to: 1) assess the microdeletion burden in common GGE syndromes, 2) estimate the relative contribution of recurrent microdeletions at genomic rearrangement hotspots and non-recurrent microdeletions, and 3) identify potential candidate genes for GGE. We found a significant excess of microdeletions in 7.3% of GGE patients compared to 4.0% in controls (P = 1.8 x 10-7; OR = 1.9). Recurrent microdeletions at seven known genomic hotspots accounted for 36.9% of all microdeletions identified in the GGE cohort and showed a 7.5-fold increased burden (P = 2.6 x 10-17) relative to controls. Microdeletions affecting either a gene previously implicated in neurodevelopmental disorders (P = 8.0 x 10-18, OR = 4.6) or an evolutionarily conserved brain-expressed gene related to autism spectrum disorder (P = 1.3 x 10-12, OR = 4.1) were significantly enriched in the GGE patients. Microdeletions found only in GGE patients harboured a high proportion of genes previously associated with epilepsy and neuropsychiatric disorders (NRXN1, RBFOX1, PCDH7, KCNA2, EPM2A, RORB, PLCB1). Our results demonstrate that the significantly increased burden of large and rare microdeletions in GGE patients is largely confined to recurrent hotspot microdeletions and microdeletions affecting neurodevelopmental genes, suggesting a strong impact of fundamental neurodevelopmental processes in the pathogenesis of common GGE syndromes.
Author Summary
Epilepsy affects about 4% of the general population during lifetime. The genetic generalised epilepsies (GGEs) represent the most common group of epilepsies with predominant genetic aetiology, accounting for 20% of all epilepsies. Despite their strong heritability, the genetic basis of the majority of patients with GGE remains elusive. Genomic microdeletions constitute a significant source of genetic risk factors for epilepsies. The present genome-wide burden analysis in 1,366 European patients with GGE and 5,234 ancestry-matched controls explored the role of large and rare microdeletions (size ≥ 400 kb, frequency < 1%) in the complex genetic architecture of common GGE syndromes. Our results revealed a 2-fold excess of microdeletions in GGE patients relative to the population controls, 2) a 7-fold increased burden for known hotspot microdeletions (15q11.2, 15q13.3, 16p13.11, 22q11.2) previously associated with a wide range of neurodevelopmental disorders, and 3) a more than 4-fold enrichment of microdeletions carrying a gene implicated in neurodevelopmental disorders. Our findings reinforce emerging evidence that genes affected by microdeletions in GGE patients have a strong impact in fundamental neurodevelopmental processes and dissect novel candidate genes involved in epileptogenesis.
PMCID: PMC4423931  PMID: 25950944
2.  Recurrent microdeletions at 15q11.2 and 16p13.11 predispose to idiopathic generalized epilepsies 
Brain  2009;133(1):23-32.
Idiopathic generalized epilepsies account for 30% of all epilepsies. Despite a predominant genetic aetiology, the genetic factors predisposing to idiopathic generalized epilepsies remain elusive. Studies of structural genomic variations have revealed a significant excess of recurrent microdeletions at 1q21.1, 15q11.2, 15q13.3, 16p11.2, 16p13.11 and 22q11.2 in various neuropsychiatric disorders including autism, intellectual disability and schizophrenia. Microdeletions at 15q13.3 have recently been shown to constitute a strong genetic risk factor for common idiopathic generalized epilepsy syndromes, implicating that other recurrent microdeletions may also be involved in epileptogenesis. This study aimed to investigate the impact of five microdeletions at the genomic hotspot regions 1q21.1, 15q11.2, 16p11.2, 16p13.11 and 22q11.2 on the genetic risk to common idiopathic generalized epilepsy syndromes. The candidate microdeletions were assessed by high-density single nucleotide polymorphism arrays in 1234 patients with idiopathic generalized epilepsy from North-western Europe and 3022 controls from the German population. Microdeletions were validated by quantitative polymerase chain reaction and their breakpoints refined by array comparative genomic hybridization. In total, 22 patients with idiopathic generalized epilepsy (1.8%) carried one of the five novel microdeletions compared with nine controls (0.3%) (odds ratio = 6.1; 95% confidence interval 2.8–13.2; χ2 = 26.7; 1 degree of freedom; P = 2.4 × 10−7). Microdeletions were observed at 1q21.1 [Idiopathic generalized epilepsy (IGE)/control: 1/1], 15q11.2 (IGE/control: 12/6), 16p11.2 IGE/control: 1/0, 16p13.11 (IGE/control: 6/2) and 22q11.2 (IGE/control: 2/0). Significant associations with IGEs were found for the microdeletions at 15q11.2 (odds ratio = 4.9; 95% confidence interval 1.8–13.2; P = 4.2 × 10−4) and 16p13.11 (odds ratio = 7.4; 95% confidence interval 1.3–74.7; P = 0.009). Including nine patients with idiopathic generalized epilepsy in this cohort with known 15q13.3 microdeletions (IGE/control: 9/0), parental transmission could be examined in 14 families. While 10 microdeletions were inherited (seven maternal and three paternal transmissions), four microdeletions occurred de novo at 15q13.3 (n = 1), 16p13.11 (n = 2) and 22q11.2 (n = 1). Eight of the transmitting parents were clinically unaffected, suggesting that the microdeletion itself is not sufficient to cause the epilepsy phenotype. Although the microdeletions investigated are individually rare (<1%) in patients with idiopathic generalized epilepsy, they collectively seem to account for a significant fraction of the genetic variance in common idiopathic generalized epilepsy syndromes. The present results indicate an involvement of microdeletions at 15q11.2 and 16p13.11 in epileptogenesis and strengthen the evidence that recurrent microdeletions at 15q11.2, 15q13.3 and 16p13.11 confer a pleiotropic susceptibility effect to a broad range of neuropsychiatric disorders.
PMCID: PMC2801323  PMID: 19843651
idiopathic generalized epilepsy; microdeletions; association; genetics
3.  Headache, epilepsy and photosensitivity: how are they connected? 
The Journal of Headache and Pain  2010;11(6):469-476.
Although headache and epilepsy have often been associated, the precise electroclinical and pathophysiological interaction between these disorders and in particular its relations with photosensitivity is as yet to be fully understood in adults or children. The association between headache and epilepsy commonly occurs in all types of epilepsy and not only in occipital epilepsy. Generally, peri-ictal headache is often neglected, regardless of its severity, because patients are more concerned about their seizures. Altered cerebral cortex excitability may be the link between these two conditions and photosensitivity shows this. The physician should bear this association in mind when dealing with epileptic and migraine patients so as to be able to offer such patients an accurate diagnosis and appropriate treatment; this should be borne in mind when declaring epileptic patients ‘seizure free’. To date neither the International Headache Society nor the International League against Epilepsy mention that headache/migraine may, on occasion, be the sole ictal epileptic manifestation. Lastly, studies designed to investigate the triggering role of photosensitivity in both headache and epilepsy are warranted.
PMCID: PMC3476223  PMID: 20963464
Peri-ictal headache; Ictal epileptic headache; PPR; Photosensitivity; Headache; Migraine; Epilepsy; Migralepsy; Hemicrania epileptica

Results 1-3 (3)