Applicability of genetic polymorphism analysis for the diagnosis of Angelman syndrome and the correlation between language difficulties and disease phenotype.

Angelman syndrome (AS) is a neurogenetic disorder caused by a defect in the expression of the maternally inherited ubiquitin protein ligase E3A (UBE3A) gene in chromosome 15. The most common genetic defects include maternal deletions in chromosome 15q11-13; however, paternal uniparental disomy and imprinting defects allow for the identification of mutations in UBE3A in 10% of patients with AS. The aim of this study was to validate the clinical features and genetic polymorphisms of AS, and to discuss the relationship between functional language lateralization and the arcuate fasciculus in the Broca's and Wernicke's areas. Six children with AS (mean age = 32.57 months) presenting characteristic behavioral patterns of AS (frequent laughter and happy demeanor, hand flapping, and hypermotor behavior) were recruited to this study. The patients underwent a clinical evaluation (clinical history, dysmorphological and neurological examinations, and psychological evaluations) and paraclinical investigations [genetic tests (fluorescence in situ hybridization and methylation polymerase chain reaction), electroencephalogram, and magnetic resonance imaging]. We conclude that AS diagnosis cannot rely solely on genetic testing for polymorphisms in UBE3A and must consider its clinical characteristics. Moreover, functional language lateralization and the arcuate fasciculus in the Broca's and Wernicke's areas were found to be closely correlated. Therefore, UBE3A gene mutation analysis combined with comprehensive clinical evaluations may be suitable for the diagnosis of AS.

Sedation with dexmedetomidine for conducting electroencephalogram in a patient with Angelman syndrome: a case report / Sedação com dexmedetomidina para realização de eletroencefalograma em paciente portadora de síndrome de Angelmann: relato de caso

ABSTRACT INTRODUCTION: Angelman syndrome is characterized by severe mental retardation and speech and seizure disorders. This rare genetic condition is associated with changes in GABAA receptor. Patients with Angelman syndrome need to be sedated during an electroencephalogram ordered for diagnostic purposes or evolutionary control. Dexmedetomidine, whose action is independent of GABA receptor, promotes a sleep similar to physiological sleep and can facilitate the performing of this examination in patients with Angelman syndrome. CASE REPORT: Female patient, 14 years old, with Angelman syndrome; electroencephalogram done under sedation with dexmedetomidine. The procedure was uneventful and bradycardia or respiratory depression was not recorded. The examination was successfully interpreted and epileptiform activity was not observed. CONCLUSION: Dexmedetomidine promoted satisfactory sedation, was well tolerated and enabled the interpretation of the electroencephalogram in a patient with Angelman syndrome and seizure disorder.

RESUMO INTRODUÇÃO: a síndrome de Angelman (SA) é caracterizada por retardo mental grave, distúrbio da fala e desordem convulsiva. Essa condição genética rara está associada a alterações do receptor GABA-A. Pacientes portadores de SA necessitam ser sedados durante a feitura de eletroencefalograma (EEG), indicado para fins diagnósticos ou controle evolutivo. A dexmedetomidina, cuja ação independe do receptor GABA, promove sono semelhante ao fisiológico e pode viabilizar a feitura desse exame em pacientes com SA. RELATO DE CASO: paciente feminina, 14 anos, portadora de SA, fez EEG sob sedação com dexmedetomidina. O procedimento transcorreu sem intercorrências e não foi registrada bradicardia ou depressão respiratória. O exame foi interpretado com sucesso e atividade epileptiforme não foi observada. CONCLUSÃO: a dexmedetomidina promoveu sedação satisfatória, foi bem tolerada e possibilitou a interpretação do EEG em paciente com SA e desordem convulsiva.

Sedation with dexmedetomidine for conducting electroencephalogram in a patient with Angelman syndrome: a case report.

INTRODUCTION: Angelman syndrome is characterized by severe mental retardation and speech and seizure disorders. This rare genetic condition is associated with changes in GABAA receptor. Patients with Angelman syndrome need to be sedated during an electroencephalogram ordered for diagnostic purposes or evolutionary control. Dexmedetomidine, whose action is independent of GABA receptor, promotes a sleep similar to physiological sleep and can facilitate the performing of this examination in patients with Angelman syndrome. CASE REPORT: Female patient, 14 years old, with Angelman syndrome; electroencephalogram done under sedation with dexmedetomidine. The procedure was uneventful and bradycardia or respiratory depression was not recorded. The examination was successfully interpreted and epileptiform activity was not observed. CONCLUSION: Dexmedetomidine promoted satisfactory sedation, was well tolerated and enabled the interpretation of the electroencephalogram in a patient with Angelman syndrome and seizure disorder.

Angelman syndrome caused by deletion: a genotype-phenotype correlation determined by breakpoint.

OBJECTIVES: Deletion of the chromosome 15q11-q13, the most common genetic mechanism associated with Angelman syndrome (AS), is highly associated with a severe phenotype. However, deletion is not a genetically homogeneous group as it is composed by two main groups: Class I with breakpoints at BP1 (proximal) and BP3 (distal) and Class II present breakpoints at BP2 (proximal) and BP3 (distal). In this study, we aimed to evaluate the impact of the breakpoint on the electroclinical profile. METHODS: We evaluated 16 patients with AS caused by 15q11-13 deletion (6 were Class I; 10 were Class II). We characterized epilepsy features by clinical history obtained from parents and caretakers with a pre-standard questionnaire. These data were corroborated by medical records, contact with previous physicians, and video-EEG monitoring. Suggestive EEG patterns for AS were classified according to the classical description of Boyd et al. (1988). RESULTS: AS patients with BP1-BP3 deletion had significantly more daily and disabling seizures than AS patients with BP1-BP2 deletion. They also presented a significant higher frequency of status epilepticus and epilepsy aggravated by fever. Need for polytherapy was significantly more frequent in BP1-BP3 patients. EEG features were similar in both groups. CONCLUSION: This study shows a significant correlation between the two deletion classes and AS clinical, but not the electrographic phenotype. Epilepsy is more severe and refractory to treatment in patients with larger deletions. Deletion is not a homogeneous group and knowledge on the breakpoint may have a clinical implication and represent an important factor in parental counseling.

Angelman syndrome: uniparental paternal disomy 15 determines mild epilepsy, but has no influence on EEG patterns.

The authors describe the electroclinical phenotype of four patients with Angelman syndrome (AS) determined by its rarest genetic mechanism-uniparental disomy (UPD). The analysis of ours and published patients showed that in UPD, when epilepsy occurred, it was milder compared to patients with deletion, although a suggestive EEG was observed in most patients. We found that UPD patients do not completely fit the scenario delineated for AS, suggesting that patients determined by different mechanisms should be distinctly addressed, for a better understanding of this syndrome.

Phenotypic variability in Angelman syndrome: comparison among different deletion classes and between deletion and UPD subjects.

Angelman syndrome (AS) can result from either a 15q11-q13 deletion (del), paternal uniparental disomy (UPD), imprinting, or UBE3A mutations. Here, we describe the phenotypic and behavioral variability detected in 49 patients with different classes of deletions and nine patients with UPD. Diagnosis was made by methylation pattern analysis of exon 1 of the SNRPN-SNURF gene and by microsatellite profiling of loci within and outside the 15q11-q13 region. There were no major phenotypic differences between the two main classes (BP1-BP3; BP2-BP3) of AS deletion patients, except for the absence of vocalization, more prevalent in patients with BP1-BP3 deletions, and for the age of sitting without support, which was lower in patients with BP2-BP3 deletions. Our data suggest that gene deletions (NIPA1, NIPA2, CYF1P1, GCP5) mapped to the region between breakpoints BP1 and BP2 may be involved in the severity of speech impairment, since all BP1-BP3 deletion patients showed complete absence of vocalization, while 38.1% of the BP2-BP3 deletion patients were able to pronounce syllabic sounds, with doubtful meaning. Compared to UPD patients, deletion patients presented a higher incidence of swallowing disorders (73.9% del x 22.2% UPD) and hypotonia (73.3% del x 28.57% UPD). In addition, children with UPD showed better physical growth, fewer or no seizures, a lower incidence of microcephaly, less ataxia and higher cognitive skills. As a consequence of their milder or less typical phenotype, AS may remain undiagnosed, leading to an overall underdiagnosis of the disease.

Angelman syndrome: difficulties in EEG pattern recognition and possible misinterpretations.

PURPOSE: This study aimed to evaluate the sensitivity of the EEG in Angelman syndrome (AS), to verify the age at onset of suggestive EEGs and to study EEG patterns, analyzing variations and comparing our findings with nomenclature previously used. METHODS: Seventy EEG and 15 V-EEGs of 26 patients were analyzed. Suggestive EEG patterns of AS were classified in delta pattern (DP), theta pattern (TP), and posterior discharges (PDs). Generic terms were used to simplify the analysis. RESULTS: Suggestive EEGs were observed in 25 (96.2%) patients. DP occurred in 22 patients with four variants-hypsarrhythmic-like: irregular, high-amplitude, generalized delta activity (DA) with multifocal epileptiform discharges (EDs); slow variant: regular, high-amplitude, generalized DA with rare EDs; ill-defined slow spike-and-wave: regular, high-amplitude, generalized DA with superimposed EDs characterizing a slow wave, with notched appearance; triphasic-like: rhythmic, moderate-amplitude DA over anterior regions with superimposed EDs. TP was observed in eight patients, as generalized or over the posterior regions. PDs were seen in 19 patients as runs of sharp waves or runs of high-amplitude slow waves with superimposed EDs. TP was the only age-related pattern (younger than 8 years) and observed only in patients with deletion. In 15 patients who had an EEG before the clinical diagnosis, 60% had a suggestive tracing. CONCLUSIONS: Although some EEG descriptions are not very detailed, and every author describes findings in a slightly different manner, obviously a common denominator must exist. In this context, EEG seems to be a very sensitive method for the diagnosis of AS, offering an opportunity to corroborate this etiologic diagnosis. Conversely, we do not believe that these patterns may be accounted as specific, except for the delta pattern, which seems to be extremely unusual in other syndromes. Other EEG patterns observed in AS, such as theta activity and PDs, occur in a wide variety of disorders. Nonetheless, their importance for the EEG diagnosis of AS is supported by the fact that they are associated with other features and may be helpful in a proper clinical setting.

[Angelman syndrome: the electroclinical characteristics in 35 patients]. / Sindrome de Angelman: características electroclínicas en 35 pacientes.

AIMS: The purpose of this study is to report on 35 patients with Angelman syndrome (AS) in whom we evaluated the electroclinical characteristics and the progression of their epilepsy. PATIENTS AND METHODS: The following factors were evaluated: sex, family background, neurological examination, age at onset and semiology of the epileptic seizures, EEG, types of epilepsy according to the international classification and response to therapy. We investigated the karyotype, and conducted FISH and methylation tests for AS. RESULTS: The 35 patients had an average follow up time of 5.6 years. Epilepsy was diagnosed in 25 cases, with an average age of onset of 1.6 years. The epileptic syndromes were: epilepsy with myoclonic seizures in 13, of which seven presented a myoclonic state in their history, focal epilepsy in seven, West's syndrome in three, and Lennox Gastaut syndrome in two. Intercritical EEG showed generalised MSW and SW paroxysms in 13, unilateral spikes in seven, hypsarrhythmia in three, generalised fast rhythm paroxysms and slow SW activity in two. Basal electroencephalographic activity was: slow hypervoltage waves with or without inserted spikes situated at the rear in 19, at the front in six, diffuse in six, and normal in four cases. CONCLUSIONS: 71.4% of patients with AS suffered epileptic seizures; epilepsy with myoclonic seizures was the most frequently observed epileptic syndrome and hypervoltage slow wave activity with or without spikes inserted in the posterior quadrants was a characteristic encephalographic pattern. In patients with mental retardation, with or without epilepsy and these electroencephalographic findings, even in the absence of characteristic clinical signs, methylation and FISH analyses for AS should be performed.

A study of EEG and epilepsy profile in Wolf-Hirschhorn syndrome and considerations regarding its correlation with other chromosomal disorders.

Wolf-Hirschhorn syndrome (WHS) is a genetic disorder caused by a deletion of the short arm of chromosome 4. Sgrò et al. described an electroclinical profile for WHS, but data regarding this issue are scarce. We report an 8-year-old girl presenting the classic phenotype for WHS, confirmed by FISH test. Epilepsy started during infancy with myoclonic seizures. Later, she presented atypical absences, which gradually increased in frequency, and at the age of 2.5 years, she presented a non-convulsive status epilepticus. Epilepsy was controlled with valproate at the age of 6 years. Serial EEGs were performed and showed unusual bursts of generalized, high amplitude delta waves with superimposed low-moderate amplitude sharp waves. A literature review was performed and our case was compared to others, where EEG and/or epilepsy were addressed. Our case and previously published data show that WHS presents a stereotyped epilepsy profile and EEG patterns. A discussion concerning similarities between these findings and those observed in Angelman syndrome has been performed, since in both syndromes, GABA genes are involved and may play a role in the pathogenesis. Although fascinating, this theory is simplistic, since patients with Angelman syndrome without GABA deletion may present epilepsy and EEG abnormalities. Another issue is the striking overlap regarding these features, between WHS and Pitt-Rogers-Danks syndrome, which may be a key in showing that these disorders could be a spectral variation of the same entity.

Clinical-neurologic, cytogenetic and molecular aspects of the Prader-Willi and Angelman syndromes.

The Prader-Willi syndrome (PWS) and the Angelman syndrome (AS) are human neurogenetic disorders involving the imprinting mechanism, at the 15q11-13 chromosome region. The predominant genetic defects in PW are 15q11-13 deletions of paternal origin and maternal chromosome 15 uniparental disomy. In contrast, maternal deletions and paternal chromosome 15 uniparental disomy are associated with a different neurogenetic disorder, the AS. In both disorders, these mutations are associated with parent-of-origin specific methylation at several 15q11-13 loci. We studied 5 patients suspect of PWS and 4 patients suspect of AS who were referred to the Medical Genetics Unit at the University Hospital of Medical School from Ribeirão Preto. Our objective was to establish the correct clinical and etiological diagnosis in these cases. We used conventional cytogenetics, methylation analysis with the probe KB17 (CpG island of the SNRPN gene) by Southern blotting after digestion with the Xba I and Not I restriction enzymes. We studied in patients and their parents the segregation of the (CA)*** repeats polymorphisms by PCR, using the primers 196 and IR4-3R. All the patients had normal conventional cytogenetical analysis. We confirmed 3 cases of PWS: one by de novo deletion, one by maternal chromosome 15 uniparental disomy and one case with no defined cause determined by the used primers. We confirmed 2 cases of AS, caused by de novo deletion at the 15q11-13 region, and one case with normal molecular analysis but with strong clinical characteristics.

Clinical-neurologic, cytogenetic and molecular aspects of the Prader-Willi and Angelman syndromes

The Prader-Willi syndrome (PWS) and the Angelman syndrome (AS) are human neurogenetic disorders involving the imprinting mechanism, at the 15q11-13 chromosome region. The predominant genetic defects in PW are 15q11-13 deletions of paternal origin and maternal chromosome 15 uniparental disomy. In contrast, maternal deletions and paternal chromosome 15 uniparental disomy are associated with a different neurogenetic disorder, the AS. In both disorders, these mutations are associated with parent-of-origin specific methylation at several 15q11-13 loci. We studied 5 patients suspect of PWS and 4 patients suspect of AS who were referred to the Medical Genetics Unit at the Universsity Hospital of Medical School from Ribeirao Preto. Our objective was to establish the correct clinical and etiological diagnosis in these cases. We used conventional cytogenetics, methylation analysis with the probe KB17 (CpG island of the SNRPN gene) by Southern blotting after digestion with the Xba I and Not I restriction enzymes. We studied in patients and their parents the segregation of the (CA)(n) repeats polymorphisms by PCR, using the primers 196 and IR4-3R. All the patients had normal conventional cytogenetical analysis. We confirmed 3 cases of PWS: one by de novo deletion, one by maternal chromosome 15 uniparental disomy and one case with no defined cause determined by the used primers. We confirmed 2 cases of AS, caused by de novo deletion at the 15q11-13 region, and one case with normal molecular analysis but with strong clinical characteristics.

Síndrome de Angelman: causa frequentemente näo reconhecida de deficiência mental e epilepsia: relato de caso / Angelman syndrome: a frequently undiagnosed cause of mental retardation and epilepsy. Case report

Os autores descrevem um caso típico de síndrome de Angelman. A paciente apresenta atraso de desenvolvimento neuropsicomotor, deficiência mental, macrostomia, dentes espaçados, convulsöes, ausência de fala, andar com a base alargada e instável, crises de risos. Os estudos citogenéticos e moleculares revelaram deleçäo do segmento 15q11q13 de origem materna, confirmando o diagnóstico clínico de síndrome de Angelman.