Search

Background The recurrent ∼ 600 kb 16p11.2 microdeletion is among the most commonly known genetic etiologies of autism spectrum disorder, overweightness, and related neurodevelopmental disorders. Case presentation Our patient is a 2-year-old white girl from the first pregnancy of a non-consanguineous healthy young white couple (father 33-years old and mother 29-years old). Our patient and her parents’ DNA were analyzed by comparative genomic hybridization-array platform. Comparative genomic hybridization-array analysis highlighted a ∼ 600 kb deletion in 16p11.2 region. It has a segregant nature, since it was found in the mother and in her 2-year-old daughter. The microdeletion was confirmed by fluorescence in situ hybridization analysis. Conclusions The presented clinical case is worthy of note since the observed microdeletion is often associated with a clinical phenotype tending to overweightness, but the proband (female) was hospitalized due to poor height and weight development, and anorexia. Moreover, the segregant nature of the observed genomic abnormality has to be noted, as well as the phenotypic variability between the mother and daughter. The case described here enriches the phenotypical spectrum linked to the 16p11.2 microdeletion. For these reasons, in the presence of a suspected genetic pathology it is fundamental to study the proband from the clinical point of view, to extend the clinical observation to the parents, and to provide a good family anamnesis. In this way, it is possible to reveal the presence of a familial genetic pathology whose phenotypical outcomes can be highly variable among the members of a family.

Objective: To identify chromosomal imbalances by whole-genome microarray-based comparative genomic hybridization (array-CGH) in DNA samples of neonates with congenital anomalies of unknown cause from a birth defects monitoring program at a public maternity hospital. Methods: A blind genomic analysis was performed retrospectively in 35 stored DNA samples of neonates born between July of 2011 and December of 2012. All potential DNA copy number variations detected (CNVs) were matched with those reported in public genomic databases, and their clinical significance was evaluated. Results: Out of a total of 35 samples tested, 13 genomic imbalances were detected in 12/35 cases (34.3%). In 4/35 cases (11.4%), chromosomal imbalances could be defined as pathogenic; in 5/35 (14.3%) cases, DNA CNVs of uncertain clinical significance were identified; and in 4/35 cases (11.4%), normal variants were detected. Among the four cases with results considered causally related to the clinical findings, two of the four (50%) showed causative alterations already associated with well-defined microdeletion syndromes. In two of the four samples (50%), the chromosomal imbalances found, although predicted as pathogenic, had not been previously associated with recognized clinical entities. Conclusions: Array-CGH analysis allowed for a higher rate of detection of chromosomal anomalies, and this determination is especially valuable in neonates with congenital anomalies of unknown etiology, or in cases in which karyotype results cannot be obtained. Moreover, although the interpretation of the results must be refined, this method is a robust and precise tool that can be used in the first-line investigation of congenital anomalies, and should be considered for prospective/retrospective analyses of DNA samples by birth defect monitoring programs. Resumo: Objetivo: Identificar desequilíbrios cromossômicos por meio da hibridização genômica comparativa baseada em microarranjos (CGH-array) em amostras de DNA de neonatos com anomalias congênitas de causa desconhecida de um programa de monitoramento de defeitos congênitos em uma maternidade pública. Métodos: Uma análise genômica cega foi realizada retrospectivamente em 35 amostras armazenadas de DNA de neonatos nascidos entre julho de 2011 e dezembro de 2012. Todas as possíveis variações no número de cópias (CNVs) de DNA foram comparadas com as relatadas em bases de dados genômicos públicas, e sua relevância clínica foi avaliada. Resultados: De um total de 35 amostras testadas, foram detectados 13 desequilíbrios genômicos em 12/35 casos (34,3%). Em 4/35 casos (11,4%), os desequilíbrios cromossômicos poderiam ser definidos como patogênicos; em 5/35 (14,3%) deles foram identificadas CNVs de DNA de relevância clínica incerta; e, em 4/35 (11,4%), foram detectadas variações normais. Dentre os quatro casos com resultados considerados relacionados causalmente aos achados clínicos, 2/4 (50%) apresentaram alterações causais já relacionadas a síndromes de microdeleção bem definidas. Em 2/4 amostras (50%), os desequilíbrios cromossômicos encontrados, embora preditivos como patogênicos, não estavam relacionados anteriormente a entidades clínicas reconhecidas. Conclusões: A análise de CGH-array permitiu maior taxa de detecção de anomalias cromossômicas, e essa determinação é valiosa principalmente em neonatos com anomalias congênitas de etiologia desconhecida ou em casos em que os resultados do cariótipo não podem ser obtidos. Além disso, embora a interpretação dos resultados deva ser refinada, esse método é uma ferramenta robusta e precisa que pode ser usada na investigação de primeira linha de anomalias congênitas e deve ser considerada em análises futuras/retrospectivas de amostras de DNA por programas de monitoramento de defeitos congênitos. Keywords: Birth defects, Congenital anomalies, Newborn selective screening, Chromosomal abnormalities, Molecular cytogenetics, Array-CGH, Palavras-chave: Defeitos congênitos, Anomalias congênitas, Triagem seletiva de recém-nascidos, Anomalias cromossômicas, Citogenética molecular, CGH-array

A genetic component to epilepsy has been recognized since Antiquity and is well established through twin and familial aggregation studies, which provide convincing evidence for the heritability of epilepsy. Despite major advances in genetic studies, genetic epilepsies have not yet revealed all their secrets. This prospective study aimed to identify genetic variants of epilepsy, to document the genotype/phenotype correlations and inheritance patterns in multigenerational Algerian families. Genetic analyzes included exome sequencing, CGH-array and Southern blotting.We studied a family with a pair of monozygotic twins affected by temporal lobe epilepsy. Exome sequencing revealed that both twins carried a novel de novo mutation (p.A39E) in the GAL gene encoding the galanin neuropeptide. This latter was found to act as a potent anticonvulsant and regulates epileptic seizures in animal models. However, until now its role in human epilepsy was not established. Functional analysis showed evidence that the mutant protein disrupts galanin signalling, and strongly supports GAL as the causal gene for the TLE in this family.We described a family with two siblings affected by temporal lobe epilepsy and psychiatric comorbidities. Exome sequencing identified a single nucleotide polymorphism in the RELN gene (rs55689103) whose mutations have been associated with epilepsy and schizophrenia.We identified two families with progressive myoclonus epilepsy type 1. Genetic studies by Southern blotting showed an expansion of dodecamer CCCCGCCCCGCG in EPM1 gene. In addition, two other families were analysed by CGH-array, but no pathogenic CNV was identified. The study of other multigenerational families would identify new genetic variants of epilepsy., L’existence d’une composante génétique dans l’épilepsie est connue depuis des années grâce aux études épidémiologiques de concordance entre jumeaux et d’agrégation familiale, qui fournissent des preuves convaincantes pour l'héritabilité de l'épilepsie. En dépit des avancées majeures des techniques d’exploration pangénomique, les épilepsies génétiques n’ont pas encore livré tous leurs secrets. Cette étude avait pour objectifs de caractériser des variants génétiques de vulnérabilité à l’épilepsie, d’étudier les modes de transmission et d’analyser les relations génotype/phénotype chez des familles Algériennes.Il s’agit d’une étude prospective menée au service de Neurologie du CHU d’Oran sur une période de 05 ans. Des familles multigénérationnelles comportant chacune au moins deux individus épileptiques ont participé à l’étude. Les analyses génétiques réalisées consistaient en un séquençage exomique de nouvelle génération, la technique de Southern Blot, et la recherche de variations du nombre de copies d’ADN (CNV) par la technique de CGH-array. Parmi les quarante familles ayant participé à l’étude, six ont bénéficié d’études génétiques. Ces études ont permis d’identifier une mutation de novo (p.A39E) dans le gène GAL codant pour le neuropeptide galanine chez des jumeaux monozygotes atteints d’épilepsie du lobe temporal (ELT). Le rôle du peptide Galanine dans la régulation du processus d’épileptogénèse a été démontré il y a plus de deux décennies sur des modèles animaux, mais à ce jour, aucune mutation GAL en rapport avec un phénotype épileptique n’avait été décrite chez l’Homme. Nous avons complété l’étude génétique par des analyses in silico qui ont confirmé l’hypothèse de causalité de la mutation identifiée, et corrélé le génotype au phénotype dans cette famille. Nos résultats pourraient avoir des retombées directes sur le développement de molécules antiépileptiques à base de galanine et de traitements par thérapie génique. Nous avons analysé une deuxième famille au phénotype d’ELT et comorbidités psychiatriques. Le séquençage exomique a mis en évidence un variant (rs55689103) du gène RELN déjà incriminé dans l’épilepsie et la schizophrénie. Nous avons identifié deux autres familles au phénotype d’épilepsie myoclonique progressive de type 1. L’étude génétique par Southern Blot a confirmé l’expansion du dodécamère CCCCGCCCCGCG dans le gène EPM1. Par ailleurs, deux autres familles ont été analysées par CGH-array, mais aucun CNV pathogène n’a été identifié par cette technique. L’étude d’autres familles multigénérationnelles permettrait d'identifier de nouveaux variants génétiques des épilepsies.

A genetic component to epilepsy has been recognized since Antiquity and is well established through twin and familial aggregation studies, which provide convincing evidence for the heritability of epilepsy. Despite major advances in genetic studies, genetic epilepsies have not yet revealed all their secrets. This prospective study aimed to identify genetic variants of epilepsy, to document the genotype/phenotype correlations and inheritance patterns in multigenerational Algerian families. Genetic analyzes included exome sequencing, CGH-array and Southern blotting.We studied a family with a pair of monozygotic twins affected by temporal lobe epilepsy. Exome sequencing revealed that both twins carried a novel de novo mutation (p.A39E) in the GAL gene encoding the galanin neuropeptide. This latter was found to act as a potent anticonvulsant and regulates epileptic seizures in animal models. However, until now its role in human epilepsy was not established. Functional analysis showed evidence that the mutant protein disrupts galanin signalling, and strongly supports GAL as the causal gene for the TLE in this family.We described a family with two siblings affected by temporal lobe epilepsy and psychiatric comorbidities. Exome sequencing identified a single nucleotide polymorphism in the RELN gene (rs55689103) whose mutations have been associated with epilepsy and schizophrenia.We identified two families with progressive myoclonus epilepsy type 1. Genetic studies by Southern blotting showed an expansion of dodecamer CCCCGCCCCGCG in EPM1 gene. In addition, two other families were analysed by CGH-array, but no pathogenic CNV was identified. The study of other multigenerational families would identify new genetic variants of epilepsy., L’existence d’une composante génétique dans l’épilepsie est connue depuis des années grâce aux études épidémiologiques de concordance entre jumeaux et d’agrégation familiale, qui fournissent des preuves convaincantes pour l'héritabilité de l'épilepsie. En dépit des avancées majeures des techniques d’exploration pangénomique, les épilepsies génétiques n’ont pas encore livré tous leurs secrets. Cette étude avait pour objectifs de caractériser des variants génétiques de vulnérabilité à l’épilepsie, d’étudier les modes de transmission et d’analyser les relations génotype/phénotype chez des familles Algériennes.Il s’agit d’une étude prospective menée au service de Neurologie du CHU d’Oran sur une période de 05 ans. Des familles multigénérationnelles comportant chacune au moins deux individus épileptiques ont participé à l’étude. Les analyses génétiques réalisées consistaient en un séquençage exomique de nouvelle génération, la technique de Southern Blot, et la recherche de variations du nombre de copies d’ADN (CNV) par la technique de CGH-array. Parmi les quarante familles ayant participé à l’étude, six ont bénéficié d’études génétiques. Ces études ont permis d’identifier une mutation de novo (p.A39E) dans le gène GAL codant pour le neuropeptide galanine chez des jumeaux monozygotes atteints d’épilepsie du lobe temporal (ELT). Le rôle du peptide Galanine dans la régulation du processus d’épileptogénèse a été démontré il y a plus de deux décennies sur des modèles animaux, mais à ce jour, aucune mutation GAL en rapport avec un phénotype épileptique n’avait été décrite chez l’Homme. Nous avons complété l’étude génétique par des analyses in silico qui ont confirmé l’hypothèse de causalité de la mutation identifiée, et corrélé le génotype au phénotype dans cette famille. Nos résultats pourraient avoir des retombées directes sur le développement de molécules antiépileptiques à base de galanine et de traitements par thérapie génique. Nous avons analysé une deuxième famille au phénotype d’ELT et comorbidités psychiatriques. Le séquençage exomique a mis en évidence un variant (rs55689103) du gène RELN déjà incriminé dans l’épilepsie et la schizophrénie. Nous avons identifié deux autres familles au phénotype d’épilepsie myoclonique progressive de type 1. L’étude génétique par Southern Blot a confirmé l’expansion du dodécamère CCCCGCCCCGCG dans le gène EPM1. Par ailleurs, deux autres familles ont été analysées par CGH-array, mais aucun CNV pathogène n’a été identifié par cette technique. L’étude d’autres familles multigénérationnelles permettrait d'identifier de nouveaux variants génétiques des épilepsies.