rs201343342
Variant summary
Our verdict is Likely benign. Variant got -2 ACMG points: 1P and 3B. PP3BP4_ModerateBP6
The NM_001406875.1(PMS2):c.-432T>C variant causes a 5 prime UTR premature start codon gain change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000162 in 1,610,676 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_001406875.1 5_prime_UTR_premature_start_codon_gain
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Likely_benign. Variant got -2 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.000145 AC: 22AN: 152214Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.000366 AC: 90AN: 245578Hom.: 0 AF XY: 0.000418 AC XY: 56AN XY: 134084
GnomAD4 exome AF: 0.000164 AC: 239AN: 1458462Hom.: 1 Cov.: 31 AF XY: 0.000183 AC XY: 133AN XY: 725560
GnomAD4 genome AF: 0.000145 AC: 22AN: 152214Hom.: 0 Cov.: 33 AF XY: 0.000161 AC XY: 12AN XY: 74358
ClinVar
Submissions by phenotype
not specified Uncertain:4Benign:1
Variant summary: PMS2 c.53T>C (p.Ile18Thr) results in a non-conservative amino acid change located in the DNA mismatch repair protein family, N-terminal of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00037 in 245578 control chromosomes. The observed variant frequency is approximately 5 fold of the estimated maximal expected allele frequency for a pathogenic variant in PMS2 causing Hereditary Nonpolyposis Colorectal Cancer phenotype (7.1e-05). c.53T>C has been reported in the literature in individuals affected with Hereditary Nonpolyposis Colorectal Cancer. However, the variant is located in a PMS2 region that shows high homology to pseudogenes, therefore this frequency data should be taken with caution. c.53T>C has been observed in a Lynch Syndrome patient with no other pathogenic mutations and with tumors that exhibited isolated loss of PMS2 expression by IHC (Vaughn_2010). It was also reported in patients with endometrial, kidney, breast and colorectal cancer, without strong evidence for causality (example, Lu_2015, Tung_2015, Tung_2016, Yurgelun_2017, Krivokuca_2021, Guindalini_2022). This variant has also been reported in an unaffected sibling and a proband in compound heterozygosity with a pathogenic exon 5 to 12 deletion (Shuen_2019). Both siblings demonstrated absent staining of PMS2 on non-neoplastic tissue. In addition, a recent large scale case-control study of breast cancer reported this variant in 13/53461 controls and 8/60466 cases (Dorling_2021). At-least one co-occurrence with another pathogenic variant has been reported (BRCA2 c.2808_2811del, p.Ala938Profs*21; Tung_2016), providing supporting evidence for a benign role. At least one publication reports experimental evidence evaluating an impact on protein function (Shuen_2019). The most pronounced variant effect results in approximately 21% mismatch repair (MMR) activity. The authors suggested that an MMR activity of 10% to 20% may represent an intermediate phenotype between classic CMMRD and Lynch syndrome. The following publications have been ascertained in the context of this evaluation (PMID: 27060170, 35264596, 22703879, 34284872, 26689913, 30608896, 25186627, 26976419, 20205264, 28135145, 30447919, 33471991). ClinVar contains an entry for this variant (Variation ID: 41714). Based on the evidence outlined above, the variant was classified as VUS-possibly benign. -
DNA sequence analysis of the PMS2 gene demonstrated a sequence change, c.53T>C, in exon 2 that results in an amino acid change, p.Ile18Thr. This sequence change has been described in the gnomAD database with a low population frequency of 0.03% in the overall population and a relatively high population frequency of 0.72% in the Ashkenazi Jewish population (dbSNP rs201343342). This sequence change was identified in a patient with colorectal cancer whose tumor exhibited isolated loss of PMS2 expression by IHC (Vaughn et al., 2010). The p.Ile18Thr change was identified in an Ashkenazi Jewish breast cancer patient who was also found to have a pathogenic sequence change in BRCA2 (Tung et al., 2016). The p.Ile18Thr change affects a highly conserved amino acid residue located in a domain of the PMS2 protein that is known to be functional. The p.Ile18Thr substitution appears to be deleterious using several in-silico pathogenicity prediction tools (SIFT, PolyPhen2, Align GVGD, REVEL). Due to these contrasting evidences and the lack of functional studies, the clinical significance of the p.Ile18Thr change remains unknown at this time. -
This variant is denoted PMS2 c.53T>C at the cDNA level, p.Ile18Thr (I18T) at the protein level, and results in the change of an Isoleucine to a Threonine (ATT>ACT). This variant was observed in at least one individual undergoing genetic testing for Lynch syndrome with a tumor that exhibited isolated loss of PMS2 by immunohistochemistry (Vaughn 2010). This variant was also reported in a patient with endometrial cancer, another with renal cancer, one with breast cancer who also carried a pathogenic variant in BRCA2 and in 2/572 individuals with atherosclerosis, with no specific information about cancer history (Johnston 2012, Lu 2015, Tung 2016). PMS2 Ile18Thr was not observed in approximately 3,600 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, suggesting it is not a common benign variant in these populations. Since Isoleucine and Threonine differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. PMS2 Ile18Thr occurs at a position that is conserved across species and is located in the ATPase domain (Guarne 2001, Fukui 2011). In silico analyses predict that this variant is probably damaging to protein structure and function. Based on currently available evidence, it is unclear whether PMS2 Ile18Thr is a pathogenic or benign variant. We consider it to be a variant of uncertain significance. -
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Hereditary cancer-predisposing syndrome Benign:3
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This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -
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Lynch syndrome Uncertain:2
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Lynch syndrome 4 Uncertain:2
This variant was determined to be of uncertain significance according to ACMG Guidelines, 2015 [PMID:25741868]. -
This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. However, the evidence from the literature, in combination with allele frequency data from public databases where available, was not sufficient to rule this variant in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -
not provided Uncertain:1Benign:1
The PMS2 p.Ile18Thr variant was identified in 6 of 2462 proband chromosomes (frequency: 0.002) from individuals or families with breast cancer, hemophilia A, and atherosclerosis (Gorski 2016, Tung 20016, Vaughn 2010, Johnston 2012). The variant was also identified in dbSNP (ID: rs201343342 as “with uncertain significance allele”), and ClinVar (6x as uncertain significance by GeneDx, Children's Hospital of Philadelphia, Color Genomics, Quest Diagnostics, Fulgent Genetics and NIH; 1x as likely benign by Ambry Genetics; and 1x as benign by Invitae) and the Insight Hereditary Tumors Database (1x as effect unknown). The variant was not identified in the COGR, Cosmic, MutDB, Zhejiang Colon Cancer, or the Mismatch Repair Genes Variant database. The variant was identified in control databases in 88 of 271252 chromosomes at a frequency of 0.0003, increasing the likelihood this could be a low frequency benign variant (Genome Aggregation Database Feb 27, 2017). The variant was identified in the following populations: Other in 1 of 6380 chromosomes (freq: 0.0002), European Non-Finnish in 13 of 122684 chromosomes (freq: 0.0001), and Ashkenazi Jewish in 74 of 9990 chromosomes (freq: 0.007); it was not observed in the African, Latino, East Asian, European Finnish, or South Asian populations. The p.Ile18Thr residue is conserved across mammals and other organisms, and 5 of 5 computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) suggest that the variant may impact the protein; however, this information is not predictive enough to assume pathogenicity. The variant occurs outside of the splicing consensus sequence and 5 of 5 in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer, HumanSpliceFinder) do not predict a difference in splicing. The variant was identified in this laboratory with a co-occurring, pathogenic MSH6 variant (c.3840_3846del, p.Glu1281Leufs*44), increasing the likelihood that the p.Ile18Thr variant does not have clinical significance. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time although we would lean towards a more benign role for this variant. This variant is classified as likely benign. -
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Breast and/or ovarian cancer Uncertain:1
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Lynch syndrome 4;C5399763:Mismatch repair cancer syndrome 1 Uncertain:1
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PMS2-related disorder Benign:1
This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -
Hereditary nonpolyposis colorectal neoplasms Benign:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at