RESUMO
BACKGROUND: ATP6V1B2 (ATPase, H+ transporting, lysosomal VI subunit B, isoform 2) encodes for a subunit of a ubiquitous transmembrane lysosomal proton pump, implicated in the acidification of intracellular organelles and in several additional cellular functions. Variants in ATP6V1B2 have been related to a heterogeneous group of multisystemic disorders sometimes associated with variable neurological involvement. However, our knowledge of genotype-phenotype correlations and the neurological spectrum of ATP6V1B2-related disorders remain limited due to the few numbers of reported cases. CASE STUDY: We hereby report the case of an 18-year-old male Sicilian patient affected by a global developmental delay, skeletal abnormalities, and epileptic encephalopathy featuring Lennox-Gastaut syndrome (LGS), in which exome sequencing led to the identification of a novel de novo variant in ATP6V1B2 (NM_001693.4: c.973G > C, p.Gly325Arg). CONCLUSIONS: Our report provides new insights on the inclusion of developmental epileptic encephalopathies (DEEs) within the continuum group of ATP6V1B2-related disorders, expanding the phenotypic and molecular spectrum associated with these conditions.
Assuntos
Epilepsia Generalizada , Epilepsia , Síndrome de Lennox-Gastaut , ATPases Vacuolares Próton-Translocadoras , Masculino , Humanos , Adolescente , Síndrome de Lennox-Gastaut/genética , Epilepsia/genética , Estudos de Associação Genética , Adenosina Trifosfatases , ATPases Vacuolares Próton-Translocadoras/genéticaRESUMO
Although there are many known Mendelian genes linked to epileptic or developmental and epileptic encephalopathy (EE/DEE), its genetic architecture is not fully explained. Here, we address this incompleteness by analyzing exomes of 743 EE/DEE cases and 2366 controls. We observe that damaging ultra-rare variants (dURVs) unique to an individual are significantly overrepresented in EE/DEE, both in known EE/DEE genes and the other non-EE/DEE genes. Importantly, enrichment of dURVs in non-EE/DEE genes is significant, even in the subset of cases with diagnostic dURVs (P = 0.000215), suggesting oligogenic contribution of non-EE/DEE gene dURVs. Gene-based analysis identifies exome-wide significant (P = 2.04 × 10-6) enrichment of damaging de novo mutations in NF1, a gene primarily linked to neurofibromatosis, in infantile spasm. Together with accumulating evidence for roles of oligogenic or modifier variants in severe neurodevelopmental disorders, our results highlight genetic complexity in EE/DEE, and indicate that EE/DEE is not an aggregate of simple Mendelian disorders.
Assuntos
Variação Genética , Espasmos Infantis/genética , Proteínas Adaptadoras de Transporte Vesicular/genética , Povo Asiático/genética , Estudos de Casos e Controles , DNA (Citosina-5-)-Metiltransferases/genética , Epilepsias Mioclônicas/genética , Fatores de Troca do Nucleotídeo Guanina/genética , Humanos , Lactente , Japão , Síndrome de Lennox-Gastaut/genética , Modelos Logísticos , Mutação , Neurofibromina 1/genética , Polimorfismo de Nucleotídeo Único , Análise de Componente Principal , Canais de Cátion TRPM/genética , Sequenciamento do ExomaRESUMO
BCL11A encodes a zinc finger protein that is highly expressed in hematopoietic tissues and the brain, and that is known to function as a transcriptional repressor of fetal hemoglobin (HbF). Recently, de novo variants in BCL11A have been reported in individuals with intellectual disability syndrome without epilepsy. In this study, we performed whole-exome sequencing of 302 patients with epileptic encephalopathies (EEs), and identified 2 novel BCL11A variants, c.577delC (p.His193Metfs*3) and c.2351A>C (p.Lys784Thr). Both the patients shared major physical features characteristic of BCL11A-related intellectual disability syndrome, suggesting that characteristic physical features and the persistence of HbF should lead clinicians to suspect EEs caused by BCL11A pathogenic variants. Patient 1, with a frameshift variant, presented with Lennox-Gastaut syndrome, which expands the phenotypic spectrum of BCL11A haploinsufficiency. Patient 2, with a p.Lys784Thr variant, presented with West syndrome followed by drug-resistant focal seizures and more severe developmental disability. These 2 newly described patients contribute to delineating the associated, yet uncertain phenotypic characteristics of BCL11A disease-causing variants.
Assuntos
Encefalopatias/genética , Proteínas de Transporte/genética , Epilepsia/genética , Deficiência Intelectual/genética , Proteínas Nucleares/genética , Adolescente , Encefalopatias/fisiopatologia , Criança , Epilepsia/fisiopatologia , Feminino , Mutação da Fase de Leitura/genética , Humanos , Recém-Nascido , Deficiência Intelectual/fisiopatologia , Síndrome de Lennox-Gastaut/genética , Síndrome de Lennox-Gastaut/fisiopatologia , Masculino , Proteínas Repressoras , Espasmos Infantis/genética , Espasmos Infantis/fisiopatologia , Sequenciamento do ExomaRESUMO
OBJECTIVE: To improve phenotype definition in genetic studies of epilepsy, we assessed the familial aggregation of focal seizure types and of specific seizure symptoms within the focal epilepsies in families from the Epilepsy Phenome/Genome Project. METHODS: We studied 302 individuals with nonacquired focal epilepsy from 149 families. Familial aggregation was assessed by logistic regression analysis of relatives' traits (dependent variable) by probands' traits (independent variable), estimating the odds ratio for each symptom in a relative given presence vs absence of the symptom in the proband. RESULTS: In families containing multiple individuals with nonacquired focal epilepsy, we found significant evidence for familial aggregation of ictal motor, autonomic, psychic, and aphasic symptoms. Within these categories, ictal whole body posturing, diaphoresis, dyspnea, fear/anxiety, and déjà vu/jamais vu showed significant familial aggregation. Focal seizure type aggregated as well, including complex partial, simple partial, and secondarily generalized tonic-clonic seizures. CONCLUSION: Our results provide insight into genotype-phenotype correlation in the nonacquired focal epilepsies and a framework for identifying subgroups of patients likely to share susceptibility genes.