rs1553640212

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1PM2PP3_Strong

The NM_000249.4(MLH1):​c.236G>A​(p.Arg79Lys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000687 in 1,455,870 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R79T) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 32)
Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

MLH1
NM_000249.4 missense

Scores

15
3
1

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: 9.42

Publications

0 publications found
Variant links:
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]
MLH1 Gene-Disease associations (from GenCC):
  • Lynch syndrome
    Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, ClinGen, Orphanet
  • Lynch syndrome 2
    Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Genomics England PanelApp
  • Muir-Torre syndrome
    Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Genomics England PanelApp, Ambry Genetics, G2P, Orphanet
  • mismatch repair cancer syndrome 1
    Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae), Orphanet, ClinGen
  • Lynch syndrome 1
    Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
  • ovarian cancer
    Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
  • malignant pancreatic neoplasm
    Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
  • rhabdomyosarcoma
    Inheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
  • prostate cancer
    Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
  • breast cancer
    Inheritance: AD Classification: NO_KNOWN Submitted by: Ambry Genetics
  • hereditary breast carcinoma
    Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

PM1
In a hotspot region, there are 15 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 42 uncertain in NM_000249.4
PM2
Very rare variant in population databases, with high coverage;
PP3
MetaRNN computational evidence supports a deleterious effect, 0.942

Transcripts

RefSeq

Gene Transcript HGVSc HGVSp Effect Exon rank MANE Protein UniProt
MLH1NM_000249.4 linkc.236G>A p.Arg79Lys missense_variant Exon 3 of 19 ENST00000231790.8 NP_000240.1 P40692-1

Ensembl

Gene Transcript HGVSc HGVSp Effect Exon rank TSL MANE Protein Appris UniProt
MLH1ENST00000231790.8 linkc.236G>A p.Arg79Lys missense_variant Exon 3 of 19 1 NM_000249.4 ENSP00000231790.3 P40692-1

Frequencies

GnomAD3 genomes
Cov.:
32
GnomAD2 exomes
AF:
0.00000398
AC:
1
AN:
251380
AF XY:
0.00
show subpopulations
Gnomad AFR exome
AF:
0.00
Gnomad AMR exome
AF:
0.00
Gnomad ASJ exome
AF:
0.00
Gnomad EAS exome
AF:
0.00
Gnomad FIN exome
AF:
0.00
Gnomad NFE exome
AF:
0.00
Gnomad OTH exome
AF:
0.00
GnomAD4 exome
AF:
6.87e-7
AC:
1
AN:
1455870
Hom.:
0
Cov.:
29
AF XY:
0.00
AC XY:
0
AN XY:
724764
show subpopulations
⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.
African (AFR)
AF:
0.00
AC:
0
AN:
33366
American (AMR)
AF:
0.00
AC:
0
AN:
44710
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
26080
East Asian (EAS)
AF:
0.00
AC:
0
AN:
39598
South Asian (SAS)
AF:
0.0000116
AC:
1
AN:
86112
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
53408
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
5748
European-Non Finnish (NFE)
AF:
0.00
AC:
0
AN:
1106630
Other (OTH)
AF:
0.00
AC:
0
AN:
60218
⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.375
Heterozygous variant carriers
0
0
1
1
2
2
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance

Age Distribution

Exome Het
Variant carriers
0
2
4
6
8
10
<30
30-35
35-40
40-45
45-50
50-55
55-60
60-65
65-70
70-75
75-80
>80
Age
GnomAD4 genome
Cov.:
32

ClinVar

Significance: Uncertain significance
Submissions summary: Uncertain:3
Revision: criteria provided, multiple submitters, no conflicts
LINK: link

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2
Sep 07, 2018
Color Diagnostics, LLC DBA Color Health
Significance:Uncertain significance
Review Status:criteria provided, single submitter
Collection Method:clinical testing

- -

Sep 15, 2023
Ambry Genetics
Significance:Uncertain significance
Review Status:criteria provided, single submitter
Collection Method:clinical testing

The p.R79K variant (also known as c.236G>A), located in coding exon 3 of the MLH1 gene, results from a G to A substitution at nucleotide position 236. The arginine at codon 79 is replaced by lysine, an amino acid with highly similar properties. This alteration was identified in an individual diagnosed with glioblastoma (Kara B et al. Turk J Pediatr, 2022;64:1106-1116). 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. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1
Jul 27, 2022
Labcorp Genetics (formerly Invitae), Labcorp
Significance:Uncertain significance
Review Status:criteria provided, single submitter
Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with lysine, which is basic and polar, at codon 79 of the MLH1 protein (p.Arg79Lys). This variant is not present in population databases (gnomAD no frequency). 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. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. ClinVar contains an entry for this variant (Variation ID: 483597). This variant has not been reported in the literature in individuals affected with MLH1-related conditions. -

Computational scores

Source: dbNSFP v4.3

Name
Calibrated prediction
Score
Prediction
AlphaMissense
Pathogenic
0.96
BayesDel_addAF
Pathogenic
0.51
D
BayesDel_noAF
Pathogenic
0.49
CADD
Pathogenic
28
DANN
Uncertain
1.0
DEOGEN2
Pathogenic
0.80
D
Eigen
Pathogenic
0.99
Eigen_PC
Pathogenic
0.96
FATHMM_MKL
Pathogenic
0.99
D
LIST_S2
Pathogenic
0.98
D
M_CAP
Pathogenic
0.29
D
MetaRNN
Pathogenic
0.94
D
MetaSVM
Pathogenic
1.0
D
MutationAssessor
Uncertain
2.8
M
PhyloP100
9.4
PrimateAI
Pathogenic
0.82
D
PROVEAN
Uncertain
-2.8
D
REVEL
Pathogenic
0.91
Sift
Pathogenic
0.0
D
Sift4G
Pathogenic
0.0
D
Polyphen
1.0
D
Vest4
0.84
MutPred
0.77
Gain of methylation at R79 (P = 0.0126);
MVP
0.97
MPC
0.41
ClinPred
1.0
D
GERP RS
5.9
RBP_binding_hub_radar
0.0
RBP_regulation_power_radar
1.1
Varity_R
0.94
gMVP
0.84
Mutation Taster
=40/60
disease causing

Splicing

Name
Calibrated prediction
Score
Prediction
SpliceAI score (max)
0.0
Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

Other links and lift over

dbSNP: rs1553640212; hg19: chr3-37042474; API