Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1PP3_Moderate
The ENST00000265849.12(PMS2):āc.197T>Cā(p.Ile66Thr) variant causes a missense change. The variant allele was found at a frequency of 0.0000281 in 1,603,236 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (ā ā ). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I66F) has been classified as Uncertain significance.
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 Uncertain_significance. Variant got 4 ACMG points.
PM1
In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 17 uncertain in ENST00000265849.12
PP3
MetaRNN computational evidence supports a deleterious effect, 0.921
Uncertain significance, criteria provided, single submitter
clinical testing
Clinical Genetics Laboratory, Skane University Hospital Lund
Jun 09, 2022
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Uncertain significance, criteria provided, single submitter
clinical testing
CeGaT Center for Human Genetics Tuebingen
Jun 01, 2023
PMS2: PM2, PS3:Supporting, BP1 -
Uncertain significance, criteria provided, single submitter
clinical testing
GeneDx
Mar 29, 2024
Demonstrated to have proficient mismatch repair efficiency in an in vitro assay (PMID: 27435373); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 34172528, 11574484, 36243179, 27435373, 32980694) -
Uncertain significance, criteria provided, single submitter
clinical testing
Quest Diagnostics Nichols Institute San Juan Capistrano
Jun 05, 2018
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Lynch syndrome 4 Uncertain:4
Uncertain significance, criteria provided, single submitter
clinical testing
Myriad Genetics, Inc.
Apr 04, 2023
This variant is classified as a variant of uncertain significance as there is insufficient evidence to determine its impact on protein function and/or cancer risk. -
Uncertain significance, criteria provided, single submitter
clinical testing
St. Jude Molecular Pathology, St. Jude Children's Research Hospital
Jul 21, 2022
The PMS2 c.197T>C (p.Ile66Thr) missense change has a maximum subpopulation frequency of 0.005% in gnomAD v2.1.1 (https://gnomad.broadinstitute.org/). The in silico tool REVEL predicts a deleterious effect on protein function and a functional study investigating mismatch repair proficiency demonstrated that this variant has intermediate relative repair efficiency compared to the wild-type (PMID: 27435373). This variant has been reported in an individual with colorectal cancer whose tumor showed weak PMS2 staining on immunohistochemistry and did not show microsatellite instability (PMID: 27435373). In summary, the evidence currently available is insufficient to determine the clinical significance of this variant. It has therefore been classified as of uncertain significance. -
Uncertain significance, criteria provided, single submitter
clinical testing
Counsyl
Feb 06, 2017
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Uncertain significance, criteria provided, single submitter
Uncertain significance, criteria provided, single submitter
clinical testing
Ambry Genetics
Feb 06, 2024
The p.I66T variant (also known as c.197T>C), located in coding exon 3 of the PMS2 gene, results from a T to C substitution at nucleotide position 197. The isoleucine at codon 66 is replaced by threonine, an amino acid with similar properties. This alteration has been detected in a Dutch individual with colorectal cancer diagnosed at age 47 whose tumor showed low microsatellite instability (MSI-L) and weak PMS2 staining on immunohistochemical analysis, and this alteration was found to have somewhat reduced mismatch repair activity compared to the wildtype PMS2 protein (van der Klift HM et al. Hum. Mutat. 2016 Nov;37:1162-1179). This amino acid position is not well conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Uncertain significance, criteria provided, single submitter
clinical testing
Color Diagnostics, LLC DBA Color Health
Mar 22, 2023
This missense variant replaces isoleucine with threonine at codon 66 of the PMS2 protein. Computational prediction tools and conservation analyses suggest that this variant may have deleterious impact on the protein function. This variant has been reported in individuals affected with colorectal cancer (PMID: 27435373, 34172528). A functional study showed that the variant protein had intermediate activity in an in vitro mismatch repair assay (PMID: 27435373). This variant has been identified in 6/282110 chromosomes in the general population by the Genome Aggregation Database (gnomAD) and has been reported in healthy individuals (PMID: 32980694). Available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
Breast and/or ovarian cancer Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario
Jan 21, 2022
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Lynch syndrome Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
All of Us Research Program, National Institutes of Health
Jul 29, 2024
This missense variant replaces isoleucine with threonine at codon 66 of the PMS2 protein. Computational prediction tools and conservation analyses suggest that this variant may have deleterious impact on the protein function. This variant has been reported in individuals affected with colorectal cancer (PMID: 27435373, 34172528). A functional study showed that the variant protein had intermediate activity in an in vitro mismatch repair assay (PMID: 27435373). This variant has been identified in 6/282110 chromosomes in the general population by the Genome Aggregation Database (gnomAD) and has been reported in healthy individuals (PMID: 32980694). Available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
Uncertain significance, criteria provided, single submitter
clinical testing
Labcorp Genetics (formerly Invitae), Labcorp
Jan 24, 2024
This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 66 of the PMS2 protein (p.Ile66Thr). This variant is present in population databases (rs769554577, gnomAD 0.005%). This missense change has been observed in individual(s) with colorectal cancer and ovarian and breast cancer (PMID: 27435373; Invitae). This missense change has been observed on the opposite chromosome (in trans) from a pathogenic variant in PMS2 in at least one individual (PMID: 27435373; Invitae), which suggests that this variant may not be disease-causing. ClinVar contains an entry for this variant (Variation ID: 185939). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt PMS2 protein function with a positive predictive value of 80%. Experimental studies have shown that this missense change affects PMS2 function (PMID: 27435373). 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. -