Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_ModeratePM2PP5_Very_Strong
The NM_000535.7(PMS2):c.2007-2A>G 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 (★★).
PMS2 (HGNC:9122): (PMS1 homolog 2, mismatch repair system component) The protein encoded by this gene is a key component of the mismatch repair system that functions to correct DNA mismatches and small insertions and deletions that can occur during DNA replication and homologous recombination. This protein forms heterodimers with the gene product of the mutL homolog 1 (MLH1) gene to form the MutL-alpha heterodimer. The MutL-alpha heterodimer possesses an endonucleolytic activity that is activated following recognition of mismatches and insertion/deletion loops by the MutS-alpha and MutS-beta heterodimers, and is necessary for removal of the mismatched DNA. There is a DQHA(X)2E(X)4E motif found at the C-terminus of the protein encoded by this gene that forms part of the active site of the nuclease. Mutations in this gene have been associated with hereditary nonpolyposis colorectal cancer (HNPCC; also known as Lynch syndrome) and Turcot syndrome. [provided by RefSeq, Apr 2016]
Verdict is Pathogenic. Variant got 12 ACMG points.
PVS1
Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.064889915 fraction of the gene. Cryptic splice site detected, with MaxEntScore 3, offset of -48, new splice context is: gtgttctataacataatcAGaaa. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 7-5982993-T-C is Pathogenic according to our data. Variant chr7-5982993-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1459392.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr7-5982993-T-C is described in Lovd as [Likely_pathogenic].
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This variant is considered likely pathogenic. This variant occurs within a consensus splice junction and is predicted to result in abnormal mRNA splicing of either an out-of-frame exon or an in-frame exon necessary for protein stability and/or normal function. -
Dec 09, 2022
Centre for Mendelian Genomics, University Medical Centre Ljubljana
Significance: Likely pathogenic
Review Status: criteria provided, single submitter
Collection Method: research
PVS1_STR, PS4_STR, PM2_SUP -
Mar 31, 2023
Baylor Genetics
Significance: Pathogenic
Review Status: criteria provided, single submitter
Review Status: criteria provided, single submitter
Collection Method: clinical testing
For these reasons, this variant has been classified as Pathogenic. This sequence change affects an acceptor splice site in intron 11 of the PMS2 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in PMS2 are known to be pathogenic (PMID: 21376568, 24362816). The frequency data for this variant in the population databases (gnomAD) is considered unreliable due to the presence of homologous sequence, such as pseudogenes or paralogs, in the genome. Disruption of this splice site has been observed in individuals with a personal and/or family history of cancer or constitutional mismatch repair deficiency syndrome (PMID: 24763289, 26318770, 30013564). ClinVar contains an entry for this variant (Variation ID: 1459392). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. -
Review Status: criteria provided, single submitter
Collection Method: clinical testing
The c.2007-2A>G intronic pathogenic mutation results from an A to G substitution two nucleotides upstream from coding exon 12 in the PMS2 gene. Alterations that disrupt the canonical splice site are expected to result in aberrant splicing. In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site and will result in the creation or strengthening of a novel splice acceptor site. The resulting transcript is predicted to be in-frame and is not expected to trigger nonsense-mediated mRNAdecay; however, direct evidence is unavailable. The exact functional effect of the altered amino acid sequence is unknown; however, a significant portion of the protein is affected (Ambry internal data). This alteration has been identified homozygous in multiple individuals with CMMRD clinical diagnosis (Lavoine N et al. J Med Genet, 2015 Nov;52:770-8). This alteration has been reported in a patient with CRC at 45 years old and first degree relative(s) with CRC and endometrial cancer (Tesch VK et al. Front Immunol, 2018 Jul;9:1506). (Wang Q et al. J Med Genet, 2020 07;57:487-499). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -