3-37008866-C-T
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Variant summary
Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1PM2PP3
The NM_000249.4(MLH1):c.506C>T(p.Pro169Leu) variant causes a missense change. The variant allele was found at a frequency of 0.00000248 in 1,613,910 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 (★★).
Frequency
Genomes: 𝑓 0.0000066 ( 0 hom., cov: 31)
Exomes 𝑓: 0.0000021 ( 0 hom. )
Consequence
MLH1
NM_000249.4 missense
NM_000249.4 missense
Scores
5
10
4
Clinical Significance
Conservation
PhyloP100: 4.26
Genes affected
MLH1 (HGNC:7127): (mutL homolog 1) The protein encoded by this gene can heterodimerize with mismatch repair endonuclease PMS2 to form MutL alpha, part of the DNA mismatch repair system. When MutL alpha is bound by MutS beta and some accessory proteins, the PMS2 subunit of MutL alpha introduces a single-strand break near DNA mismatches, providing an entry point for exonuclease degradation. The encoded protein is also involved in DNA damage signaling and can heterodimerize with DNA mismatch repair protein MLH3 to form MutL gamma, which is involved in meiosis. This gene was identified as a locus frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). [provided by RefSeq, Aug 2017]
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ACMG classification
Classification made for transcript
Verdict is Uncertain_significance. Variant got 5 ACMG points.
PM1
In a helix (size 17) in uniprot entity MLH1_HUMAN there are 7 pathogenic changes around while only 1 benign (88%) in NM_000249.4
PM2
Very rare variant in population databases, with high coverage;
PP3
MetaRNN computational evidence supports a deleterious effect, 0.782
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | Protein | UniProt |
---|---|---|---|---|---|---|---|---|
MLH1 | NM_000249.4 | c.506C>T | p.Pro169Leu | missense_variant | 6/19 | ENST00000231790.8 | NP_000240.1 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Protein | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|---|
MLH1 | ENST00000231790.8 | c.506C>T | p.Pro169Leu | missense_variant | 6/19 | 1 | NM_000249.4 | ENSP00000231790 | P1 |
Frequencies
GnomAD3 genomes AF: 0.00000658 AC: 1AN: 152070Hom.: 0 Cov.: 31
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GnomAD3 exomes AF: 0.00000398 AC: 1AN: 251430Hom.: 0 AF XY: 0.00000736 AC XY: 1AN XY: 135888
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GnomAD4 exome AF: 0.00000205 AC: 3AN: 1461840Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0AN XY: 727224
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GnomAD4 genome AF: 0.00000658 AC: 1AN: 152070Hom.: 0 Cov.: 31 AF XY: 0.0000135 AC XY: 1AN XY: 74280
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ClinVar
Significance: Uncertain significance
Submissions summary: Uncertain:6
Revision: criteria provided, multiple submitters, no conflicts
LINK: link
Submissions by phenotype
Hereditary cancer-predisposing syndrome Uncertain:2
Uncertain significance, criteria provided, single submitter | clinical testing | Color Diagnostics, LLC DBA Color Health | Jan 18, 2023 | This missense variant replaces proline with leucine at codon 169 of the MLH1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in trans with a pathogenic MLH1 variant in an individual affected with gastric cancer (PMID: 16237216) and in a suspected hereditary nonpolyposis colorectal cancer family (Salehi, 2008). This variant has been identified in 1/251430 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The 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 | Ambry Genetics | Mar 15, 2022 | The p.P169L variant (also known as c.506C>T), located in coding exon 6 of the MLH1 gene, results from a C to T substitution at nucleotide position 506. The proline at codon 169 is replaced by leucine, an amino acid with similar properties. This alteration was identified in a cohort of Iranian patients whose personal and family cancer history meets the Amsterdam criteria (Salehi M et al. J Sci I Iran. 2009; 20(1):7-12). This variant was reportedly detected in conjunction (phase unknown) with a pathogenic mutation in MLH1 in a 35-year-old male with mixed proximal gastric cancer (Bacani J et al. J Mol Diagn. 2005 Oct;7:465-77). This amino acid position is highly 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. - |
Colorectal cancer, hereditary nonpolyposis, type 2 Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Baylor Genetics | Mar 05, 2024 | - - |
Lynch syndrome Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | All of Us Research Program, National Institutes of Health | Oct 23, 2023 | This missense variant replaces proline with leucine at codon 169 of the MLH1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). Splice site prediction tools suggest that this variant may not impact RNA splicing. To our knowledge, functional studies have not been reported for this variant. This variant has been reported in trans with a pathogenic MLH1 variant in an individual affected with gastric cancer (PMID: 16237216) and a suspected hereditary nonpolyposis colorectal cancer family (https://jsciences.ut.ac.ir/article_31909.html). This variant has been identified in 1/251430 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The 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. - |
not provided Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | GeneDx | Jul 21, 2023 | Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; In silico analysis is inconclusive as to whether the variant alters gene splicing. In the absence of RNA/functional studies, the actual effect of this sequence change is unknown.; Observed in a patient with mixed proximal gastric cancer with deficient MLH1 by IHC, who also harbored a pathogenic MLH1 variant (PMID: 16237216); This variant is associated with the following publications: (PMID: 26333163, 32027066, 33471991, 22753075, 16237216) - |
Hereditary nonpolyposis colorectal neoplasms Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Labcorp Genetics (formerly Invitae), Labcorp | Jan 30, 2024 | This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 169 of the MLH1 protein (p.Pro169Leu). This variant is present in population databases (rs63750834, gnomAD 0.0009%). This missense change has been observed in individual(s) with suspected Lynch syndrome (PMID: 31391288). ClinVar contains an entry for this variant (Variation ID: 90251). An algorithm developed specifically for the MLH1 gene suggests that this missense change is likely to be deleterious (PMID: 26333163). Studies have shown this missense change is associated with skipping of exon 6, but one or more of the resulting mRNA isoform(s) may be naturally occurring (Invitae). 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. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
AlphaMissense
Benign
BayesDel_addAF
Pathogenic
D
BayesDel_noAF
Pathogenic
CADD
Uncertain
DANN
Uncertain
DEOGEN2
Uncertain
D;.;T
Eigen
Uncertain
Eigen_PC
Uncertain
FATHMM_MKL
Pathogenic
D
LIST_S2
Uncertain
D;D;D
M_CAP
Benign
T
MetaRNN
Pathogenic
D;D;D
MetaSVM
Benign
T
MutationAssessor
Uncertain
M;.;.
MutationTaster
Benign
D;D;D;D;D;D
PrimateAI
Uncertain
T
PROVEAN
Pathogenic
D;D;D
REVEL
Uncertain
Sift
Uncertain
D;D;D
Sift4G
Uncertain
D;D;T
Polyphen
B;.;.
Vest4
MVP
MPC
ClinPred
D
GERP RS
Varity_R
gMVP
Splicing
Name
Calibrated prediction
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Prediction
SpliceAI score (max)
Details are displayed if max score is > 0.2
DS_DL_spliceai
Position offset: 39
Find out detailed SpliceAI scores and Pangolin per-transcript scores at