Biomedical subjects

N Bahi-Buisson

Publications and source records attributed to N Bahi-Buisson.

7 recordsLinked to original sources

PubMed2006

[Update on the genetics of X-linked mental retardation].

Mutations in X-linked genes are likely to account for the observation that more males than females are affected with mental retardation. Causative mutations have been identified in both syndromic XLMR and in the genetically heterogeneous non-syndromic forms of XLMR, without a clear clinical phenotype other than cognitive deficit. Progress in genome analysis and the establishment of large collaborations between clinical and molecular research teams, especially the European XLMR consortium, have led to the identification of 20 non-syndromic XLMR genes and 25 syndromic XLMR genes. Given the extensive heterogeneity of non syndromic XLMR, different strategies are used for the identification of new genes: linkage analysis, studies of balanced chromosomal rearrangements (X-autosome translocations, microdeletions) and candidate genes strategies by mutation screening in regions of the X chromosome known to be involved in neuronal development and function. Delineating the monogenic causes of XLMR and their molecular and cellular consequences will provide insight into the mechanisms that are required for normal development of cognitive function in humans. Non syndromic XLMR proteins include 5 distinct classes: transmembrane receptors, small GTPases effectors or regulators, enzymes and translational regulators.

Chromosomes, Human, X↗

PubMed2006

Molar tooth sign and superior vermian dysplasia: a radiological, clinical, and genetic study.

We have identified a group of 13 patients with a homogeneous radiological pattern at MRI consisting of the molar tooth sign (MTS) and superior vermian dysplasia. The patients represent a relatively heterogeneous clinical group with variable severity of developmental delay, ataxia, hypotonia, and apnea. Careful examination of MRI prompted us to split our series of patients into two groups, based on IVth ventricle dilatation. In 4/13 patients the IVth ventricle was judged to be dilated and those patients were less severely affected while most clinically affected patients had a normal IVth ventricle. DNA samples of blood leukocytes from 6/13 consanguineous patients were genotyped using polymorphic markers encompassing the Joubert syndrome loci. We therefore sequenced AHI1 located in 6q23 in two patients who were homozygous at the locus and in four sporadic cases. Only one homozygous nonsense mutation was identified. Clinically, the patient exhibiting the AHI1 mutation was the most severely affected child with a profound encephalopathy, major hypotonia, ataxia, Leber congenital amaurosis, and normal IVth ventricle at the MRI. The present study suggests that the syndrome associating MTS and dysplasia of the superior vermis of the cerebellum is a clinically and genetically heterogeneous entity and that Jouberin (AHI1) mutations account for a marginal fraction of patients.

Abnormalities, Multiple↗

PubMed2005

[Neonatal epilepsy and inborn errors of metabolism].

Metabolic disorders constitute an important cause of neurologic disease, including neonatal epilepsy. Epilepsy rarely dominates the clinical presentation, which is more frequently associated with other neurologic symptoms, such as hypotonia and/or vigilance disturbances. In most cases, epilepsy secondary to inherited metabolic disorders presents with polymorphic clinical and electrographic features that are difficult to classify into precise epileptic syndromes. However, specific types of seizures, such as myoclonic seizures or distinctive electroencephalographic patterns, such as suppression burst patterns, epileptic syndrome or early myoclonic encephalopathy, may suggest a specific metabolic disease. The aim of this article is to help clinicians in reviewing potential metabolic diagnoses and approaching metabolic evaluations.

Age Factors↗

PubMed2005

[Epilepsy in chromosome aberrations].

Epilepsy is among the most frequent finding in many chromosome aberrations. While most chromosome aberrations can be associated with different seizure types, there are few aberrations which feature specific seizures and EEG patterns. Among the 400 different chromosomal imbalances described with seizures and EEG abnormalities, eight have a high association with epilepsy. These comprise: the monosomy 1p36, Wolf-Hirschhorn syndrome (4p-), Angelman syndrome, Miller-Dieker del 17p13.3, the inversion duplication 15 syndrome, ring 20 and ring 14 syndromes, Down's syndrome. These chromosomal regions where aberrations have an evident association with epilepsy may be useful targets for gene hunters. On the other hand, a better characterisation of epileptic syndrome in these disorders may lead to a better and specific treatment.

Child↗

PubMed2005

[Recent advances in pathogenic concepts and therapeutic strategies in Rasmussen's encephalitis].

Rasmussen's encephalitis (RE) is a rare inflammatory brain disease mainly affecting children and characterised by intractable epilepsy involving a single hemisphere that undergoes progressive atrophy. RE is characterized by refractory focal seizures, often associated with epilepsia partialis continua, progressive unilateral motor defect, slow EEG activity over the entire contralateral hemisphere, with focal white matter hyperintensity and insular cortical atrophy on neuroimaging. Surgical exclusion of the affected hemisphere is the only treatment that interrupts progression of the disease. Pathogenic concepts have considered viruses, autoimmune antibodies and autoimmune cytotoxic T lymphocytes that might contribute to the initiating or perpetuating events in the central nervous system. Based on these concepts, different therapeutic strategies have been pursued, such as antiviral agents, plasmapheresis, immuno-adsorption, immunosuppression or immunomodulation with intravenous immunoglobulins. However, due to the lack of large studies, to date there is no established therapeutic strategy for this devastating condition. In this review, we give an overview of the current state of immunopathogenic concepts for Rasmussen's encephalitis and discuss the different therapeutic options for future perspectives.

Early Diagnosis↗

PubMed2004

[Treatment of status epilepticus in children with epilepsy].

The treatment of status epilepticus (SE) in children with epilepsy depends on the epilepsy syndrome, in order to avoid worsening drugs such as IV barbiturates in severe myoclonic epilepsy in infancy (SMEI) (Dravet's syndrome) or IV benzodiazepam in tonic SE of Lennox-Gastaut syndrome. Intensive care procedures should not be systematical in convulsive SE (CSE) and are not indicated in non-convulsive SE (NCSE). Generalized CSE mostly involve SMEI before 3 years of age, symptomatic generalized epilepsy and partial lesional epilepsy. Treatment is an emergency and relies on IV benzodiazepines and, if necessary, IV phenytoine using plasmatic concentrations for an optimal management. The partial CSE of partial lesional epilepsy can result in focal deficit and need the same treatment as generalized CSE. NCSE consist in absence and/or myoclonic SE and are often unrecognised during a long time until EEG is performed. They mostly involve myoclonic epilepsies and can be controlled by IV benzodiazepines. The frequency of partial NCSE is underestimated, particularly in infants. Diagnosis relies on video EEG and treatment is the same as that used in partial CSE.

Anticonvulsants↗

PubMed2003

Absence of mutations in major GEFS+ genes in myoclonic astatic epilepsy.

Myoclonic astatic epilepsy (MAE) is a genetically determined condition of childhood onset characterized by multiple generalized types of seizures including myoclonic astatic seizures, generalized spike waves and cognitive deterioration. This condition has been reported in a few patients in generalized epilepsy with febrile seizures plus (GEFS+) families and MAE has been considered, like severe myoclonic epilepsy of infancy (SMEI), to be a severe phenotype within the GEFS+ spectrum. Four genes have been identified in GEFS+ families, but only three (SCN1A, SCNlB, GABRG2) were found in MAE patients within GEFS+ families. We analysed these three genes in a series of 22 sporadic patients with MAE and found no causal mutations. These findings suggest that MAE, unlike SMEI, is not genetically related to GEFS+. Although MAE and SMEI share the same types of seizures, only SMEI patients are sensitive to fever. This is probably its main link to GEFS+. A different family of genes is likely to account for MAE.

Child, Preschool↗