Genetic Variant MLH3:p.Cys279Trp (chr14-75048819-G-C) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_001040108.2(MLH3):c.837C>G(p.Cys279Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,830 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. C279C) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

MLH3
NM_001040108.2 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 0.521

Publications

0 publications found

Variant links:

Genes affected

MLH3 (HGNC:7128): (mutL homolog 3) This gene is a member of the MutL-homolog (MLH) family of DNA mismatch repair (MMR) genes. MLH genes are implicated in maintaining genomic integrity during DNA replication and after meiotic recombination. The protein encoded by this gene functions as a heterodimer with other family members. Somatic mutations in this gene frequently occur in tumors exhibiting microsatellite instability, and germline mutations have been linked to hereditary nonpolyposis colorectal cancer type 7 (HNPCC7). Several alternatively spliced transcript variants have been identified, but the full-length nature of only two transcript variants has been determined. [provided by RefSeq, Jul 2008]

MLH3 Gene-Disease associations (from GenCC):

colorectal cancer, hereditary nonpolyposis, type 7
Inheritance: AD, AR Classification: MODERATE, LIMITED Submitted by: Ambry Genetics, ClinGen, Laboratory for Molecular Medicine

MLH3 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH3	NM_001040108.2 link	c.837C>G	p.Cys279Trp	missense_variant	Exon 2 of 13	ENST00000355774.7	NP_001035197.1	Q9UHC1-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
MLH3	ENST00000355774.7 link	c.837C>G	p.Cys279Trp	missense_variant	Exon 2 of 13	5	NM_001040108.2	ENSP00000348020.2	Q9UHC1-1
MLH3	ENST00000380968.6 link	c.837C>G	p.Cys279Trp	missense_variant	Exon 2 of 12	1		ENSP00000370355.3	Q9UHC1-2
MLH3	ENST00000556257.5 link	c.837C>G	p.Cys279Trp	missense_variant	Exon 2 of 7	5		ENSP00000451540.1	G3V419

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461830

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727206

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:

AN:

33478

American (AMR)

AF:

0.00

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39694

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86242

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111980

Other (OTH)

AF:

0.00

AC:

AN:

60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), 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

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.77

BayesDel_addAF

Uncertain

0.15

BayesDel_noAF

Uncertain

-0.020

CADD

Benign

(source)

DANN

Uncertain

0.99

DEOGEN2

Uncertain

0.69

D;.;.;D

Eigen

Uncertain

0.42

Eigen_PC

Uncertain

0.35

FATHMM_MKL

Uncertain

0.93

LIST_S2

Uncertain

0.90

D;D;D;.

M_CAP

Uncertain

0.12

MetaRNN

Uncertain

0.58

D;D;D;D

MetaSVM

Uncertain

0.37

MutationAssessor

Uncertain

2.1

M;M;.;M

PhyloP100

0.52

PrimateAI

Uncertain

0.58

PROVEAN

Pathogenic

-5.8

D;.;D;D

REVEL

Uncertain

0.64

Sift

Uncertain

0.010

D;.;D;D

Sift4G

Pathogenic

0.0

D;D;D;D

Polyphen

1.0

D;D;.;D

Vest4

0.47

MutPred

0.51

Gain of catalytic residue at K280 (P = 0.0037);Gain of catalytic residue at K280 (P = 0.0037);Gain of catalytic residue at K280 (P = 0.0037);Gain of catalytic residue at K280 (P = 0.0037);

MVP

0.92

MPC

0.59

ClinPred

0.98

GERP RS

3.1

Varity_R

0.84

gMVP

0.62

Mutation Taster

=81/19

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over