Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PVS1_ModeratePM2
The NM_000268.4(NF2):c.1738-4_1741delACAGCTCAinsG(p.Leu580fs) variant causes a frameshift, splice acceptor, splice region, intron change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).
NF2 (HGNC:7773): (NF2, moesin-ezrin-radixin like (MERLIN) tumor suppressor) This gene encodes a protein that is similar to some members of the ERM (ezrin, radixin, moesin) family of proteins that link cytoskeletal components with proteins in the cell membrane. The encoded protein is involved in regulation of contact-dependent inhibition of cell proliferation and functions in cell-cell adhesion and transmembrane signaling. The encoded protein has been shown to interact with cell-surface proteins, proteins involved in cytoskeletal dynamics, and proteins involved in regulating ion transport. Disruption of this protein's function has been implicated in tumorigenesis and metastasis. Mutations in this gene are associated with neurofibromatosis type II which is characterized by nervous system and skin tumors and ocular abnormalities. [provided by RefSeq, May 2022]
Verdict is Uncertain_significance. Variant got 4 ACMG points.
PVS1
Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.028 CDS is truncated, and there are 0 pathogenic variants in the truncated region.
PM2
Very rare variant in population databases, with high coverage;
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change affects an acceptor splice site in the last intron (intron 15) of the NF2 gene. While this is not anticipated to result in nonsense mediated decay, it likely alters RNA splicing and results in a disrupted protein product. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with NF2-related conditions. ClinVar contains an entry for this variant (Variation ID: 457909). Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. 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. -