rs1060502926
Variant summary
Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_000179.3(MSH6):c.3556+1G>A variant causes a splice donor, 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 (★★).
Frequency
Consequence
NM_000179.3 splice_donor, intron
Scores
Clinical Significance
Conservation
Publications
- intellectual developmental disorder with dysmorphic facies and behavioral abnormalitiesInheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
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ACMG classification
Our verdict: Pathogenic. The variant received 18 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes Cov.: 32
GnomAD4 exome Cov.: 27
GnomAD4 genome Cov.: 32
ClinVar
Submissions by phenotype
Hereditary cancer-predisposing syndrome Pathogenic:2
The c.3556+1G>A intronic pathogenic mutation results from a G to A substitution one nucleotide after coding exon 6 of the MSH6 gene. This variant has been identified in a proband who met Amsterdam I/II criteria for Lynch syndrome and tumor demonstrated loss of MSH6 expression by immunohistochemistry (Ambry internal data). In silico splice site analysis predicts that this alteration will weaken the native splice donor site. RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). Other alterations impacting the same donor site (c.3556+1G>T and c.3556+2T>G) have been shown to have a similar impact on splicing and were identified in probands meeting Amsterdam I/II criteria for Lynch syndrome/HNPCC and/or had loss of MSH6 expression in their tumors by immunohistochemistry (Ambry internal data; Hirotsu Y et al. Mol Genet Genomic Med, 2015 Sep;3:459-66). 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 a disease-causing mutation. -
This variant causes a G>A nucleotide substitution at the +1 position of intron 6 of the MSH6 gene. Splice site prediction tools suggest that this variant may have a significant impact on RNA splicing. Although this prediction has not been confirmed in published RNA studies, this variant is expected to result in an absent or disrupted protein product. This variant has not been reported in individuals affected with MSH6-related disorders in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Different variants affecting the same splice donor site, c.3556+1G>T and c.3556+1G>C, are described to be disease-causing (ClinVar variation ID: 646634, 572617). The c.3556+1G>T variant has been observed in an individual affected with ovarian cancer, with tumor data showing high macrosatellite instability and loss of MSH6 protein via immunohistochemistry , and analysis performed with patient peripheral blood RNA demonstrated reduced mRNA expression levels compared to controls (PMID: 26436112). Loss of MSH6 function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Pathogenic. -
Lynch syndrome 5 Pathogenic:1
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. -
not provided Pathogenic:1
Canonical splice site variant predicted to result in a null allele in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 26436112) -
Hereditary nonpolyposis colorectal neoplasms Pathogenic:1
This sequence change affects a donor splice site in intron 6 of the MSH6 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or altered protein product. This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with clinical features of Lynch syndrome (PMID: 26436112). ClinVar contains an entry for this variant (Variation ID: 410489). Studies have shown that disruption of this splice site results in skipping of exon 6, and produces a non-functional protein and/or introduces a premature termination codon (PMID: 26436112; internal data). For these reasons, this variant has been classified as Pathogenic. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at