Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1PM2PP5_Moderate
The NM_003106.4(SOX2):c.157dupC(p.Arg53ProfsTer43) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★).
SOX2 (HGNC:11195): (SRY-box transcription factor 2) This intronless gene encodes a member of the SRY-related HMG-box (SOX) family of transcription factors involved in the regulation of embryonic development and in the determination of cell fate. The product of this gene is required for stem-cell maintenance in the central nervous system, and also regulates gene expression in the stomach. Mutations in this gene have been associated with optic nerve hypoplasia and with syndromic microphthalmia, a severe form of structural eye malformation. This gene lies within an intron of another gene called SOX2 overlapping transcript (SOX2OT). [provided by RefSeq, Jul 2008]
SOX2-OT (HGNC:20209): (SOX2 overlapping transcript) This gene produces alternatively spliced long non-coding RNAs. These RNAs were observed to be upregulated in tumor cells and positively correlated to expression of the SRY-box 2 gene. Overexpression of these transcripts may promote cell proliferation. [provided by RefSeq, Dec 2017]
Our verdict: Pathogenic. The variant received 12 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. There are 72 pathogenic variants in the truncated region.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 3-181712514-T-TC is Pathogenic according to our data. Variant chr3-181712514-T-TC is described in ClinVar as Pathogenic. ClinVar VariationId is 467821.Status of the report is criteria_provided_single_submitter, 1 stars.
For these reasons, this variant has been classified as Pathogenic. A different truncation downstream of this variant (p.Gln177*) has been determined to be pathogenic (PMID: 12612584, 16932809). This suggests that deletion of this region of the SOX2 protein is causative of disease. This variant has not been reported in the literature in individuals with a SOX2-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change results in a premature translational stop signal in the SOX2 gene (p.Arg53Profs*43). While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 265 amino acids (~83%) of the SOX2 protein. -