1. bookVolume 47 (2020): Issue 1 (May 2020)
Journal Details
License
Format
Journal
eISSN
2719-5384
First Published
05 Nov 2014
Publication timeframe
4 times per year
Languages
English
access type Open Access

Molecular-Genetic Diagnostics of Angelman Syndrome – The Bulgarian Experience

Published Online: 21 May 2020
Volume & Issue: Volume 47 (2020) - Issue 1 (May 2020)
Page range: 9 - 16
Received: 01 May 2019
Accepted: 01 Jun 2019
Journal Details
License
Format
Journal
eISSN
2719-5384
First Published
05 Nov 2014
Publication timeframe
4 times per year
Languages
English
Abstract

Objective: The aim of the study was to determine the molecular mechanisms of mutagenesis in Bulgarian patients with Angelman syndrome (AS). AS is a severe neurodevelopmental disorder caused by loss of expression in brain of the maternally inherited UBE3A gene as a result of various 15q11.2-q13 alterations.

Material and Methods: In total 24 patients (11 boys, 13 girls) from 22 unrelated families with suspected clinical diagnosis AS were analysed. We used methylation specific PCR, multiplex ligation-dependent probe amplification, methylation sensitive MLPA, and direct sequencing of the UBE3A gene.

Results: In 9 families (41%) pathogenic mutations were detected, which confirmed the clinical diagnosis on а molecular-genetic level. In 4 (44%) of these families we found 15q11-q13 region deletion with breakpoints BP1-BP3 or BP2-BP3. In 1 (11%) of the families we found imprinting defect: deletion of the AS-SRO regulatory region (part of the PWS-AS imprinting center). In 1 (11%) of the families we detected a rare finding – paternal uniparental disomy of chromosome 15. In 3 (33%) of the families diff erent point mutations in the UBE3A gene were detected: two novel missence mutations c.488T > C; p.Leu163Ser and c.1832A > T; p.Gln611Leu, and one known frameshift mutation c.2576_2579delAAGA; p.Lys859Argfs*4.

Conclusion: The obtained results helped us to develop a systematic diagnostic algorithm in order to provide proper diagnosis for the patients with AS. Combining excellent knowledge of the molecular mechanisms of mutagenesis and proper molecular-genetic testing approaches is a cornerstone in the management of AS patients, ensuring AS families would receive both adequate genetic counseling and prophylaxis of the disease in the future.

Keywords

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