Angelman syndrome revisited

Ocular findings and strabismus surgery outcomes in Chinese children with Angelman syndrome: Three case reports

RATIONALE

Angelman syndrome (AS) is an uncommon genetic disease characterized as serious retarded mental development and ocular abnormality.

PATIENT CONCERNS

This report aims to present the ophthalmological features, and identify the diagnosis and outcomes of strabismus surgery in AS patients.

DIAGNOSIS

Three children with exotropia were diagnosed with AS based on their typical clinical features.

INTERVENTIONS

All patients underwent multiplex ligation-dependent probe amplification (MLPA) analysis and accepted lateral rectus recession surgery with the assistance of intravenous combined inhalation anesthesia.

OUTCOMES

The maternal heritage deletion of chromosome 15q11.2-q13 was verified in all patients by MLPA. All patients with strabismus could not cooperate during the vision test, and had astigmatism. The strabismus type of AS patients was horizontal exotropia, and no vertical strabismus was found. One of these patients was combined with high myopia. The hypopigmentation on the hair and iris was ubiquitous. However, retina pigmentation was normal. After different degrees of lateral rectus recession, the exotropia was significantly relieved, and the surgical effects were stable postoperatively.

LESSONS

Horizontal exotropia is the major strabismus type. Severe intellectual disability, hyperactivity, and speech impairment are the common characteristics of AS children. Its examination and operation design remains challenging. Thus, repeated examinations and intelligence rehabilitation are essential.

Vagal nerve stimulation for medically refractory epilepsy in Angelman syndrome: a series of three cases

BACKGROUND

We describe three children with Angelman syndrome and medically refractory epilepsy.

METHODS

Case series of three pediatric patients with Angelman syndrome and medically refractory epilepsy. All three patients failed medical treatment and were recommended for vagal nerve stimulator (VNS) implantation.

RESULTS

Following VNS implantation, all three patients experienced reduction in seizure frequency greater than that afforded by medication alone.

CONCLUSION

We present vagal nerve stimulator implantation as a viable treatment option for medically refractory epilepsy associated with Angelman syndrome.

Melatonin and Angelman Syndrome: Implications and Mathematical Model of Diurnal Secretion

The main aim of the study was to compare the melatonin rhythms in subjects with Angelman syndrome (n = 9) and in children with (n = 80) and without (n = 40) epilepsy (nonepileptic patients diagnosed with peripheral nerve palsies, myopathy, and back pain) using our mathematical model of melatonin circadian secretion. The characteristics describing the diurnal hormone secretion such as minimum melatonin concentration, release amplitude, phase shift of melatonin release, and sleep duration as well as the dim light melatonin onset (DLMO) of melatonin secretion and the γ shape parameter allow analyzing the fit and deducing about how much the measured melatonin profile differs from a physiological bell-shaped secretion. The estimated sleep duration and phase shift of melatonin release as well as the DMLO offsets at 25% and 50% relative thresholds are the key characteristic of Angelman syndrome children. As revealed from the γ shape parameter, the melatonin secretion profiles are disturbed in majority of the AG subjects revealing rather a triangular course instead of the bell-like one.

Unmet clinical needs and burden in Angelman syndrome: a review of the literature

Background

Angelman syndrome (AS) is a rare disorder with a relatively well-defined phenotype. Despite this, very little is known regarding the unmet clinical needs and burden of this condition, especially with regard to some of the most prevalent clinical features—movement disorders, communication impairments, behavior, and sleep.

Main text

A targeted literature review using electronic medical databases (e.g., PubMed) was conducted to identify recent studies focused on specific areas of the AS phenotype (motor, communication, behavior, sleep) as well as epidemiology, diagnostic processes, treatment, and burden. 142 articles were reviewed and summarized. Findings suggest significant impairment across the life span in all areas of function. While some issues may resolve as individuals get older (e.g., hyperactivity), others become worse (e.g., movement disorders, aggression, anxiety). There are no treatments focused on the underlying etiology, and the symptom-based therapies currently prescribed do not have much, if any, empirical support.

Conclusions

The lack of standardized treatment protocols or approved therapies, combined with the severity of the condition, results in high unmet clinical needs in the areas of motor functioning, communication, behavior, and sleep for individuals with AS and their families.

Seizure treatment in Angelman syndrome: A case series from the Angelman Syndrome Clinic at Massachusetts General Hospital

Epilepsy is a common feature of Angelman syndrome (~80-90%), with the most common seizure types including myoclonic, atonic, atypical absence, focal, and generalized tonic-clonic. Seizure types are similar among the various genetic subtypes, but epilepsy in those with maternal deletions is more frequent and more refractory to medication. Treatment with older antiepileptic drugs such as valproic acid and clonazepam is effective, but these medications tend to have less favorable side effect profiles in Angelman syndrome compared with those in newer medications. This study aimed to assess the use of newer antiepileptic drug therapies in individuals with Angelman syndrome followed at the Angelman Syndrome Clinic at the Massachusetts General Hospital. Many of the subjects in this study were on valproic acid therapy prior to their initial evaluation and exhibited increased tremor, decreased balance, and/or regression of motor skills, which resolved after tapering off of this medication. Newer antiepileptic drugs such as levetiracetam, lamotrigine, and clobazam, and to a lesser extent topiramate, appeared to be as effective - if not more so - as valproic acid and clonazepam while offering more favorable side effect profiles. The low glycemic index treatment also provided effective seizure control with minimal side effects. The majority of subjects remained on combination therapy with levetiracetam, lamotrigine, and clobazam being the most commonly used medications, indicating a changing trend when compared with prior studies.

Altered ultrasonic vocalization and impaired learning and memory in Angelman syndrome mouse model with a large maternal deletion from Ube3a to Gabrb3

Angelman syndrome (AS) is a neurobehavioral disorder associated with mental retardation, absence of language development, characteristic electroencephalography (EEG) abnormalities and epilepsy, happy disposition, movement or balance disorders, and autistic behaviors. The molecular defects underlying AS are heterogeneous, including large maternal deletions of chromosome 15q11–q13 (70%), paternal uniparental disomy (UPD) of chromosome 15 (5%), imprinting mutations (rare), and mutations in the E6-AP ubiquitin ligase gene UBE3A (15%). Although patients with UBE3A mutations have a wide spectrum of neurological phenotypes, their features are usually milder than AS patients with deletions of 15q11–q13. Using a chromosomal engineering strategy, we generated mutant mice with a 1.6-Mb chromosomal deletion from Ube3a to Gabrb3, which inactivated the Ube3a and Gabrb3 genes and deleted the Atp10a gene. Homozygous deletion mutant mice died in the perinatal period due to a cleft palate resulting from the null mutation in Gabrb3 gene. Mice with a maternal deletion (m−/p+) were viable and did not have any obvious developmental defects. Expression analysis of the maternal and paternal deletion mice confirmed that the Ube3a gene is maternally expressed in brain, and showed that the Atp10a and Gabrb3 genes are biallelically expressed in all brain sub-regions studied. Maternal (m−/p+), but not paternal (m+/p−), deletion mice had increased spontaneous seizure activity and abnormal EEG. Extensive behavioral analyses revealed significant impairment in motor function, learning and memory tasks, and anxiety-related measures assayed in the light-dark box in maternal deletion but not paternal deletion mice. Ultrasonic vocalization (USV) recording in newborns revealed that maternal deletion pups emitted significantly more USVs than wild-type littermates. The increased USV in maternal deletion mice suggests abnormal signaling behavior between mothers and pups that may reflect abnormal communication behaviors in human AS patients. Thus, mutant mice with a maternal deletion from Ube3a to Gabrb3 provide an AS mouse model that is molecularly more similar to the contiguous gene deletion form of AS in humans than mice with Ube3a mutation alone. These mice will be valuable for future comparative studies to mice with maternal deficiency of Ube3a alone.

A "happy" toddler presenting with sudden, life-threatening seizures

Angelman syndrome is often associated with medically refractory epilepsy. Here, we report the case of a young girl with Angelman syndrome who experienced frequent and prolonged atonic seizures associated with dysautonomia and was unresponsive to multiple antiepileptic drugs, but who responded dramatically to the ketogenic diet. Clinicians are encouraged to consider the ketogenic diet early in the treatment course of patients with Angelman syndrome.

Benefit of corticosteroid therapy in Angelman syndrome

Angelman syndrome is often associated with an intractable seizure disorder. We describe 4 children who demonstrated an excellent response to corticosteroid therapy. The benefits included not only reduction in clinical seizures but also modification of the "typical'' Angelman electroencephalogram. In addition, there was improvement in the myoclonic jerks, sleep pattern, and developmental progress. Corticosteroids appeared to have a broad benefit on the epileptic encephalopathy. We believe that these cases pose a challenge to the conventional management of intractable epilepsy in Angelman syndrome.