EEG Patterns in Patients with Prader-Willi Syndrome

Epilepsy, EEG and chromosomal rearrangements

Chromosomal abnormalities are associated with a broad spectrum of clinical manifestations, one of the more commonly observed of which is epilepsy. The frequency, severity, and type of epileptic seizures vary according to the macro- and microrearrangements present. Even within a single chromosomal anomaly, we most often deal with a phenotypic spectrum. The aim of the study was to look for chromosomal rearrangements with a characteristic electroencephalographic pattern. Only a few disorders have peculiar electroclinical abnormalities: 1p36, 4p16, 6q terminal or trisomy 12p, Angelman syndrome, inv dup 15, 15q13.3 deletions, ring 20, Down syndrome, or Xp11.22-11.23 duplication. We also reviewed studies on epileptic seizures and typical electroencephalographic patterns described in certain chromosomal rearrangements, focusing on the quest for potential electroclinical biomarkers. The comprehensive review concludes with clinical presentations of the most common micro and macro chromosomal rearrangements, such as 17q21.31 microdeletion, 6q terminal deletion, 15q inv dup syndrome, 2q24.4 deletion, Xp11.22-11.23 duplication, 15q13.3 microdeletion, 1p36 terminal deletion, 5q14.3 microdeletion, and Xq28 duplication. The papers reviewed did not identify any specific interictal electroencephalographic patterns that were unique and significant biomarkers for a given chromosomal microrearrangement. The types of seizures described varied, with both generalized and focal seizures of various morphologies being reported. Patients with chromosomal anomalies may also meet the criteria for specific epileptic syndromes such as Infantile Epilepsy Spasms Syndrome (IESS, West syndrome): 16p13.11, 15q13.3 and 17q21.31 microdeletions, 5q inv dup. syndrome; Dravet syndrome (2q24.4 deletion), Lennox-Gastaut syndrome (15q11 duplication. 1q13.3, 5q inv dup.); or Self-Limited Epilepsy with Autonomic Features (SeLEAS, Panayiotopoulos syndrome: terminal deletion of 6q.n), Self-Limited Epilepsy with Centrotemporal Spikes (SeLECT): fragile X syndrome. It is essential to better characterize groups of patients to more accurately define patterns of epilepsy and EEG abnormalities. This could lead to new treatment strategies. Future research is required to better understand epileptic syndromes and chromosomal rearrangements. PLAIN LANGUAGE SUMMARY: This paper presents EEG recording abnormalities in patients with various gene abnormalities that can cause epilepsy. The authors summarize these EEG variations based on a literature review to see if they occur frequently enough in other chromosomal abnormalities (in addition to those already known) to be a clue for further diagnosis.

Prevalence and genotypic associations of epilepsy in Prader-Willi Syndrome: A systematic review and meta-analysis

OBJECTIVE

To estimate the prevalence of epilepsy and febrile seizures and their association with genotype, i.e., 15q11-q13 deletions, uniparental chromosome 15 disomy (UPD) and other mutations, in the population with Prader-Willi syndrome (PWS).

METHODS

A systematic search of Medline, Scopus, Web of Science and the Cochrane Library was conducted. Studies estimating the prevalence of seizures, epilepsy and febrile seizures in the PWS population were included. Meta-analyses of the prevalence of epilepsy and febrile seizures and their association with genotype using the prevalence ratio (PR) were performed.

RESULTS

Fifteen studies were included. The prevalence of epilepsy was 0.11 (0.07, 0.15), similar to the prevalence of febrile seizures, with a prevalence of 0.09 (0.05, 0.13). The comparison "deletion vs. UPD" had a PR of 2.03 (0.90, 4.57) and 3.76 (1.54, 9.18) for epilepsy and febrile seizures.

CONCLUSIONS

The prevalence of seizure disorders in PWS is higher than in the general population. In addition, deletions in 15q11-q13 may be associated with a higher risk of seizure disorders. Therefore, active screening for seizure disorders in PWS should improve the lives of these people. In addition, genotype could be used to stratify risk, even for epilepsy, although more studies or larger sample sizes are needed.

Interstitial 6q deletion in a patient presenting with drug-resistant epilepsy and Prader-Willi like phenotype: An electroclinical description with literature review

PURPOSE

Interstitial 6q deletions are associated with rare genetic syndromes characterized by different signs, including developmental delay, dysmorphisms, and Prader-Willi (PWS)-like features. Drug-resistant epilepsy, a relatively rare finding in this condition, is often a challenge in terms of therapeutic approach. Our aim is to present a new case of interstitial 6q deletion and to conduct a systematic review of the literature with an emphasis on the neurophysiological and clinical traits of afflicted individuals.

METHODS

We report a patient with an interstitial 6q deletion. Standard electroencephalograms (EEG), video-EEG with polygraphy and MRI features are discussed. We also conducted a literature review of previously described cases.

RESULTS

We describe a relatively small interstitial 6q deletion (2 Mb circa), detected by CGH-Array, not encompassing the previously described 6q22 critical region for epilepsy occurrence. The patient, a 12-year-old girl, presented with multiple absence-like episodes and startle-induced epileptic spasms since the age of 11, with partial polytherapy control. Treatment with lamotrigine induced the resolution of startle-induced phenomena. From the literature review, we identified 28 patients with overlapping deletions, often larger than our patient's mutation. Seventeen patients presented with PWS-like features. Epilepsy was reported in 4 patients, and 8 patients presented abnormal EEG findings. In our patient, the deletion included genes MCHR2, SIM1, ASCC3, and GRIK2, but, interestingly, it did not encompass the 6q22 critical region for epilepsy occurrence. The involvement of GRIK2 in the deletion may play a role.

CONCLUSION

Literature data are limited, and specific EEG or epileptological phenotypes cannot yet be identified. Epilepsy, although uncommon in the syndrome, deserves a specific diagnostic workup. We speculate on the existence of an additional locus in the 6q16.1-q21 region, different from the already hypothesized q22, promoting the development of epilepsy in affected patients.

Longitudinal analysis of electroencephalography pattern changes in an infant with Schaaf-Yang syndrome and a novel mutation in melanoma antigen L2 (MAGEL2)

Background

Schaaf‐Yang syndrome (SYS) is a rare hereditary disease caused by truncating point mutations of the paternal allele of melanoma antigen L2 (MAGEL2), one of five protein‐coding genes within the Prader‐Willi syndrome (PWS) critical domain. SYS shares many clinical and molecular characteristics with PWS but has some distinct features, such as joint contractures and autism. Patients with PWS show abnormal electroencephalography (EEG) patterns. However, there are very few reports on EEG findings in patients with SYS.

Methods

A SYS patient was included in this study. Detailed neurological examinations and EEG were performed from neonate to infant ages. Sanger sequencing was performed.

Results

Our patient presented abnormal EEG findings and had diffuse brain dysfunction symptoms including a reduced level of consciousness, diminished spontaneous movements, hypotonia, feeding difficulties, and hypoventilation from early after birth. As she grew older and her background activity of EEG normalized, her neurodevelopmental symptoms remained but improved. Sanger sequencing of this patient revealed a novel, heterozygous c.2005C > T, truncating mutation in the MEGAL2 gene.

Conclusions

We described an SYS‐associated, time‐dependent, EEG pattern in a patient with SYS. Our findings of longitudinal EEG changes in a patient with SYS revealed a specific pattern of how affected individuals develop brain function.