Our verdict is Uncertain significance. Variant got 2 ACMG points: 3P and 1B. PM2PP2BP4
The NM_130839.5(UBE3A):c.2344G>T(p.Val782Phe) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,461,142 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).
UBE3A (HGNC:12496): (ubiquitin protein ligase E3A) This gene encodes an E3 ubiquitin-protein ligase, part of the ubiquitin protein degradation system. This imprinted gene is maternally expressed in brain and biallelically expressed in other tissues. Maternally inherited deletion of this gene causes Angelman Syndrome, characterized by severe motor and intellectual retardation, ataxia, hypotonia, epilepsy, absence of speech, and characteristic facies. The protein also interacts with the E6 protein of human papillomavirus types 16 and 18, resulting in ubiquitination and proteolysis of tumor protein p53. Alternative splicing of this gene results in three transcript variants encoding three isoforms with different N-termini. Additional transcript variants have been described, but their full length nature has not been determined. [provided by RefSeq, Jul 2008]
SNHG14 (HGNC:37462): (small nucleolar RNA host gene 14) This gene is located within the Prader-Willi critical region and produces a long, spliced paternally-imprinted RNA that initiates within a common upstream promoter region shared by the SNRPN (small nuclear ribonucleoprotein polypeptide N) and SNURF genes. This transcript serves as a host RNA for the small nucleolar RNA, C/D box 115 and 116 clusters. This RNA extends in antisense into the region of the ubiquitin protein ligase E3A gene (UBE3A), and is thought to regulate imprinted expression of UBE3A in the brain. This transcript undergoes extensive alternative splicing, and may initiate and terminate at multiple locations within this genomic region. The full-length structure of all splice forms is not determined. [provided by RefSeq, Mar 2017]
Verdict is Uncertain_significance. Variant got 2 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
PP2
Missense variant in the UBE3A gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 44 curated pathogenic missense variants (we use a threshold of 10). The gene has 8 curated benign missense variants. Trascript score misZ: 6.9443 (above the threshold of 3.09). GenCC associations: The gene is linked to Angelman syndrome.
BP4
Computational evidence support a benign effect (MetaRNN=0.3059991).
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change replaces valine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 762 of the UBE3A protein (p.Val762Phe). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with UBE3A-related conditions. Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt UBE3A protein function with a negative predictive value of 80%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -