Familial form of typical childhood absence epilepsy in a consanguineous context

Clinical and genetic study of Tunisian families with genetic generalized epilepsy: contribution of CACNA1H and MAST4 genes

Genetic generalized epilepsies (GGE) (childhood absence epilepsy (CAE), juvenile myoclonic epilepsy (JME) and epilepsy with generalized tonic-clonic seizures (GTCS)) are mainly determined by genetic factors. Since few mutations were identified in rare families with autosomal dominant GGE, a polygenic inheritance was suspected in most patients. Recent studies on large American or European cohorts of sporadic cases showed that susceptibility genes were numerous although their variants were rare, making their identification difficult. Here, we reported clinical and genetic characteristics of 30 Tunisian GGE families, including 71 GGE patients. The phenotype was close to that in sporadic cases. Nineteen pedigrees had a homogeneous type of GGE (JME-CAE-CGTS), and 11 combined these epileptic syndromes. Rare non-synonymous variants were selected in probands using a targeted panel of 30 candidate genes and their segregation was determined in families. Molecular studies incriminated different genes, mainly CACNA1H and MAST4. The segregation of at least two variants in different genes in some pedigrees was compatible with the hypothesis of an oligogenic inheritance, which was in accordance with the relatively low frequency of consanguineous probands. Since at least 2 susceptibility genes were likely shared by different populations, genetic factors involved in the majority of Tunisian GGE families remain to be discovered. Their identification should be easier in families with a homogeneous type of GGE, in which an intra-familial genetic homogeneity could be suspected.

Familial epilepsy in Algeria: Clinical features and inheritance profiles

PURPOSE

To document the clinical characteristics and inheritance pattern of epilepsy in multigeneration Algerian families.

METHODS

Affected members from extended families with familial epilepsy were assessed at the University Hospital of Oran in Algeria. Available medical records, neurological examination, electroencephalography and imaging data were reviewed. The epilepsy type was classified according to the criteria of the International League Against Epilepsy and modes of inheritance were deduced from pedigree analysis.

RESULTS

The study population included 40 probands; 23 male (57.5%) and 17 female subjects (42.5%). The mean age of seizure onset was 9.5 ± 6.1 years. According to seizure onset, 16 patients (40%) had focal seizures and 20 (50%) had generalized seizures. Seizure control was achieved for two patients (5%) for 10 years, while 28 (70%) were seizure-free for 3 months. Eleven patients (27.5%) had prior febrile seizures, 12 were diagnosed with psychiatric disorders and four families had syndromic epilepsy. The consanguinity rate among parents of affected was 50% with phenotypic concordance observed in 25 families (62.5%). Pedigree analysis suggested autosomal dominant (AD) inheritance with or without reduced penetrance in 18 families (45%), probable autosomal recessive (AR) inheritance in 14 families (35%), and an X-linked recessive inheritance in one family.

CONCLUSION

This study reveals large Algerian families with multigenerational inheritance of epilepsy. Molecular testing such as exome sequencing would clarify the genetic basis of epilepsy in some of our families.

Clinical and inheritance profile of familial childhood epilepsy in Jordan

PURPOSE

To present the clinical profiles and inheritance patterns of familial childhood epilepsy in the highly consanguineous population of Jordan.

METHODS

This retrospective study examined children diagnosed with epilepsy and having at least one epileptic parent or sibling. The epilepsy type was classified according to the criteria of the International League Against Epilepsy. Patients were monitored for a period of 6 months to 5 years.

RESULTS

The study population included 39 children belonging to 31 families; 21 boys (53.8%) and 18 girls (46.2%). The age at onset ranged from one month to 16 years. Generalized seizures were observed in 23 patients (58.9%), partial seizures in 14 patients (35.8%); and generalized and partial seizures in two patients (5.1%). Seizure control was achieved in 33 patients (84.6%), and 13 patients (33.3%) were seizure-free for at least two years. Withdrawal of antiepileptic medication was successful in five of these 13 patients (38.5%), while seizures recurred in the other eight (61.5%) on withdrawal. The consanguinity rate among parents of affected children was 61.3%. Pedigree analysis suggested probable autosomal dominant (AD) inheritance with or without reduced penetrance in 13 families (41.9%), probable autosomal recessive (AR) inheritance in 6 families (19.4%), and an X-linked recessive inheritance (XR) in one family.

CONCLUSIONS

This is the first report on familial epilepsy involving first degree relatives in Jordan. Genetic testing including exome sequencing could help in reaching the accurate diagnosis and may also reveal novel autosomal recessive genes associated with pediatric idiopathic epilepsy.

The expanding social network of ionotropic glutamate receptors: TARPs and other transmembrane auxiliary subunits

Ionotropic glutamate receptors (iGluRs) underlie rapid, excitatory synaptic signaling throughout the CNS. After years of intense research, our picture of iGluRs has evolved from them being companionless in the postsynaptic membrane to them being the hub of dynamic supramolecular signaling complexes, interacting with an ever-expanding litany of other proteins that regulate their trafficking, scaffolding, stability, signaling, and turnover. In particular, the discovery that transmembrane AMPA receptor regulatory proteins (TARPs) are AMPA receptor auxiliary subunits that are critical determinants of their trafficking, gating, and pharmacology has changed the way we think about iGluR function. Recently, a number of novel transmembrane proteins have been uncovered that may also serve as iGluR auxiliary proteins. Here we review pivotal developments in our understanding of the role of TARPs in AMPA receptor trafficking and gating, and provide an overview of how newly discovered transmembrane proteins expand our view of iGluR function in the CNS.