Identification of Novel UBE3A Mutation Causing Angelman Syndrome

The Angelman Syndrome (AS) is neurodevelopmental disease associated with maternal disruption of the UBE3A gene and is mainly characterized by global developmental delay, sever mental retardation with absence of speech, seizures, dysmorphic facial features, and distinct behavioral profile. In this study a pedigree with one affected member with neurodevelopmental disease who was a result of an unconsanguineous marriage were investigated by Whole Exome Sequencing (WES). DNA was extracted from whole blood and library was prepared using Agilent V6 capturing system. WES was performed on Illumina HiSeq 4000 platform. Genome Analysis Toolkit (GATK) was used for variant calling. Classification of selected variants was done based on ACMG guideline for variant interpretation 2015. WES revealed that the proband has previously unreported nonsense variant (c.2459T>G) in UBE3A gene that causes the substitution of Leu (TTA) with stop codon (TGA), confirming the diagnosis of Angelman syndrome. The patient had delayed motor development, speech impairment, an attention deficit, and an abnormal electroencephalogram (EEG), but no seizures by the age of 2 years. This study emphasis the role of WES in the early diagnosis and better management for AS patient.