Impact of Deletion on Angelman Syndrome Phenotype Variability: Phenotype–Genotype Correlation in 97 Patients with Motor Developmental Delay

Hanae Daha Belghiti; Meriame Abbassi; Hanane Sayel; Mohamed Ahakoud; Badr Eddine El Makhzen; Norman Lee; Silvia Russo; Sana Chaouki; Laila Bouguenouch

doi:10.1055/s-0042-1751268

Journal of Pediatric Genetics, Table of Contents

J Pediatr Genet 2024; 13(01): 015-021
DOI: 10.1055/s-0042-1751268

Original Article

Impact of Deletion on Angelman Syndrome Phenotype Variability: Phenotype–Genotype Correlation in 97 Patients with Motor Developmental Delay

Hanae Daha Belghiti

¹Medical Center of Biomedical and Translational Research, Hassan II University Hospital, Fez, Morocco

,

Meriame Abbassi

²Unit of Medical Genetics and Oncogenetics, University Hospital Hassan II, Fez, Morocco

,

Hanane Sayel

²Unit of Medical Genetics and Oncogenetics, University Hospital Hassan II, Fez, Morocco

,

Mohamed Ahakoud

²Unit of Medical Genetics and Oncogenetics, University Hospital Hassan II, Fez, Morocco

,

Badr Eddine El Makhzen

²Unit of Medical Genetics and Oncogenetics, University Hospital Hassan II, Fez, Morocco

,

Norman Lee

³Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, United States

,

Silvia Russo

⁴Istituto Auxologico Italiano Istituto di Ricovero e Cura a Carattere Scientifico, Cytogenetics and Molecular Genetics Laboratory, Milano, Lombardia, Italy

,

Sana Chaouki

⁵Department of Neuropediatrics, Hospital University Hassan II, Fez, Morocco

,

Laila Bouguenouch

²Unit of Medical Genetics and Oncogenetics, University Hospital Hassan II, Fez, Morocco

› Author Affiliations

Abstract

Angelman syndrome (AS) is a rare neurodevelopmental disorder due to genetic defects involving chromosome 15, known by intellectual disability, cognitive and behavioral disorders, ataxia, delayed motor development, and seizures. This study highlights the clinical spectrum and molecular research to establish the genotype–phenotype correlation in the pediatric Moroccan population. Methylation-specific-polymerase chain reaction (MS-PCR) is a primordial technique not only to identify the genetic mechanism of AS but also to characterize the different molecular classes induced in the appearance of the clinical symptoms. Patients with positive methylation profile were additionally studied by fluorescent in situ hybridization. Sequencing analysis of the UBE3A gene was performed for patients with negative MS-PCR. We used Fisher's test to assess differences in the distribution of features frequencies among the deletional and the nondeletional group. Statistical analysis was performed using R project. We identified from 97 patients diagnosed with AS, 14 (2.06%) had a classical AS phenotype, while 70 (84.5%) patients displayed a subset of consistent and frequent criteria. Development delay was shown severe in 63% and moderate in 37%. Nineteen out of 97 of them had MS-PCR positive in which 17 (89.47%) had 15q11-q13 deletion. Deletion patients presented a higher incidence of epileptic seizures (p = 0.04), ataxia (p = 0.0008), and abnormal electroencephalogram (EEG) profile (p = 0.003). We further found out a frameshift deletion located at exon 9 of the UBE3A gene discovered in a 5 years old patient. We report in this study the genotype–phenotype correlation using different molecular testing. Correlation analysis did not reveal any statistical differences in phenotypic dissimilarity between deletion and nondeletion groups for most clinical features, except the correlation was highly significant in the abnormal EEG. According to our findings, we recommend offering MS-PCR analysis to all patients with severe intellectual disability, developmental delay, speech impairment, happy demeanor, and hypopigmentation.

Keywords

Angelman syndrome - deletion - UBE3A - Methylation-specific-polymerase chain reaction

Full Text

References

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