rs201541505
Variant summary
Our verdict is Benign. Variant got -7 ACMG points: 1P and 8B. PP3BP6_Very_Strong
The NM_000249.4(MLH1):c.1040C>A(p.Thr347Asn) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Benign (★★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T347I) has been classified as Benign.
Frequency
Consequence
NM_000249.4 missense, splice_region
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Benign. Variant got -7 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00 AC: 30AN: 116394Hom.: 0 Cov.: 26 FAILED QC
GnomAD3 exomes AF: 0.0000547 AC: 10AN: 182724Hom.: 0 AF XY: 0.0000591 AC XY: 6AN XY: 101458
GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.00246 AC: 2056AN: 835610Hom.: 0 Cov.: 24 AF XY: 0.00230 AC XY: 968AN XY: 420194
GnomAD4 genome Data not reliable, filtered out with message: AS_VQSR AF: 0.000240 AC: 28AN: 116424Hom.: 0 Cov.: 26 AF XY: 0.000278 AC XY: 15AN XY: 53878
ClinVar
Submissions by phenotype
not specified Uncertain:1Benign:6
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Variant summary: MLH1 c.1040C>A (p.Thr347Asn) results in a non-conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 7.3e-05 in 206178 control chromosomes. This frequency is not significantly higher than expected for a pathogenic variant in MLH1 causing Lynch Syndrome (7.3e-05 vs 0.00071), allowing no conclusion about variant significance. c.1040C>A has been reported in the literature in at-least one proband affected with colorectal cancer (Thompson_2013). This report(s) does not provide unequivocal conclusions about association of the variant with Lynch Syndrome. Additionally, it was reported in a patient with sporadic etiology for colorectal cancer as evidenced by BRAF mutation positivity, high MSI, and a negative MLH1 and PMS2 staining by IHC (van der Klift_2016). BRAF mutation and MLH1 promoter hypermethylation have been reported as strong predictors of a negative germline MMR mutational status (Parsons_2012, PMID 22368298). To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Four ClinVar submissions from clinical diagnostic laboratories (evaluation after 2014) cite the variant as uncertain significance. Additionally, one submission indicates the variant co-occurred with a pathogenic PMS2 variant (variant not indicated). In addition, an expert panel submitter, InSiGHT, and another submitter (evaluation before 2014) have classified the variant as benign. Therefore, based on the evidence outlined above, the variant was classified as likely benign. -
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Variant identified in a genome or exome case(s) and assessed due to predicted null impact of the variant or pathogenic assertions in the literature or databases. Disclaimer: This variant has not undergone full assessment. The following are preliminary notes: This variant is in the second base of exon 12 (of 19 exons). This variant is present in ExAC and gnomAD at a MaxMAF of 0.01% (15 alleles). It is classified in ClinVar as Benign by Ambry and an expert panel (InSiGHT - 3 stars) and as VUS by Invitae and GeneDx. It has not been reported in affected individuals but was seen in the Invitae database in a patient who had another PMS2 variant that was likely to explain disease. -
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not provided Uncertain:2Benign:1
MLH1: BS1, BS2 -
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This variant is denoted MLH1 c.1040C>A at the cDNA level, p.Thr347Asn (T347N) at the protein level, and results in the change of a Threonine to an Asparagine (ACT>AAT). The International Society for Gastrointestinal Hereditary Tumours Incorporated (InSiGHT) classifies this variant as benign based on a multifactorial model that incorporates in silico models and segregation within families; however, this data is not available for independent review (Thompson 2013, Thompson 2014). MLH1 Thr347Asn was observed at an allele frequency of 0.013% (14/101,232) in individuals of European ancestry in large population cohorts (Lek 2016). MLH1 Thr347Asn is not located in a known functional domain. In-silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect. Based on currently available information, it is unclear whether MLH1 Thr347Asn is pathogenic or benign. We consider it to be a variant of uncertain significance. -
Hereditary cancer-predisposing syndrome Benign:3
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This alteration is classified as 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. -
Colorectal cancer, hereditary nonpolyposis, type 2 Benign:1
This variant is considered benign. This variant has been observed in trans with a known pathogenic variant in one or more individuals lacking clinical features consistent with gene-specific recessive disease. This variant is strongly associated with less severe personal and family histories of cancer, typical for individuals without pathogenic variants in this gene [PMID: 27363726]. -
Lynch syndrome Benign:1
Multifactorial likelihood analysis posterior probability <0.001 -
Hereditary nonpolyposis colorectal neoplasms Benign:1
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Hereditary breast ovarian cancer syndrome Benign:1
According to the ACMG SVI adaptation criteria we chose these criteria: BP4 (supporting benign): Posterior probability Thompson et al., 2013/InSiGHT: 0.0002, BS1 (strong benign): gnomAD all 0.007275%, in EUR 0.01384% (cut off VCEP >0,01% BS1) -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at