Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PVS1_ModeratePM2PP5_Moderate
The NM_000251.3(MSH2):c.2459-2A>T variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).
MSH2 (HGNC:7325): (mutS homolog 2) This locus is frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). When cloned, it was discovered to be a human homolog of the E. coli mismatch repair gene mutS, consistent with the characteristic alterations in microsatellite sequences (RER+ phenotype) found in HNPCC. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Apr 2012]
Verdict is Likely_pathogenic. Variant got 6 ACMG points.
PVS1
Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.0627451 fraction of the gene. Cryptic splice site detected, with MaxEntScore 6.5, offset of 36, new splice context is: ttttgggattcatgttgcAGagc. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 2-47480694-A-T is Pathogenic according to our data. Variant chr2-47480694-A-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1791582.Status of the report is criteria_provided_single_submitter, 1 stars.
Review Status: criteria provided, single submitter
Collection Method: clinical testing
The c.2459-2A>T intronic variant results from an A to T substitution two nucleotides upstream from coding exon 15 in the MSH2 gene. This nucleotide position is highly conserved in available vertebrate species. Using the BDGP and ESEfinder splice site prediction tools, this alteration is predicted to abolish the native splice acceptor site; however, direct evidence is unavailable. Alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as likely pathogenic. -