Genetic Variant MLH1:c.207+1G>A (chr3-36996710-G-A) – ACMG Classification: Pathogenic (22 pts)

Variant summary

Our verdict is Pathogenic. The variant received 22 ACMG points: 22P and 0B. PVS1PS3PM2PP5_Very_Strong

The NM_000249.4(MLH1):c.207+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000248 in 1,609,672 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★★). ClinVar reports functional evidence for this variant: "SCV000172723: RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data).". The gene MLH1 is included in the ClinGen Criteria Specification Registry.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

MLH1
NM_000249.4 splice_donor, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Likely pathogenic reviewed by expert panel P:10

Conservation

PhyloP100: 9.51

Publications

6 publications found

Variant links:

COSMIC-nc: COSV51613936

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: ClinGen, Orphanet, G2P
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: Labcorp Genetics (formerly Invitae), Orphanet, Ambry Genetics, G2P, 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

MLH1 links:

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ACMG classification

Specifications for MLH1 are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Classification was made for transcript

Our verdict: Pathogenic. The variant received 22 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.

PS3

PS3 evidence extracted from ClinVar submissions: SCV000172723: RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data).

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 3-36996710-G-A is Pathogenic according to our data. Variant chr3-36996710-G-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 90020.Status of the report is reviewed_by_expert_panel, 3 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000249.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein	UniProt
MLH1	NM_000249.4	MANE Select	c.207+1G>A	splice_donor intron	N/A	NP_000240.1	P40692-1
MLH1	NM_001354628.2		c.207+1G>A	splice_donor intron	N/A	NP_001341557.1	A0A087WX20
MLH1	NM_001354629.2		c.207+1G>A	splice_donor intron	N/A	NP_001341558.1	A0AAQ5BGZ2

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein	UniProt
MLH1	ENST00000231790.8	TSL:1 MANE Select	c.207+1G>A	splice_donor intron	N/A	ENSP00000231790.3	P40692-1
MLH1	ENST00000456676.7	TSL:1	c.207+1G>A	splice_donor intron	N/A	ENSP00000416687.3	H0Y818
MLH1	ENST00000413740.2	TSL:1	c.207+1G>A	splice_donor intron	N/A	ENSP00000416476.2	H0Y806

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152198

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1457474

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

725496

show subpopulations

African (AFR)

AF:

0.0000300

AC:

AN:

33388

American (AMR)

AF:

0.00

AC:

AN:

44710

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26118

East Asian (EAS)

AF:

0.00

AC:

AN:

39658

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86158

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53396

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5758

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1108044

Other (OTH)

AF:

0.00

AC:

AN:

60244

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.575

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<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

AF:

0.0000131

AC:

AN:

152198

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74352

show subpopulations

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.0000483

AC:

AN:

41444

American (AMR)

AF:

0.00

AC:

AN:

15284

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5200

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10614

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68034

Other (OTH)

AF:

0.00

AC:

AN:

2092

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.0448430), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.350

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

ClinVar

ClinVar submissions

Significance:Likely pathogenic

Revision:reviewed by expert panel

View on ClinVar

Pathogenic

VUS

Benign

Condition

Hereditary cancer-predisposing syndrome (3)

not provided (3)

Colorectal cancer, hereditary nonpolyposis, type 2 (2)

Hereditary nonpolyposis colorectal neoplasms (1)

Lynch syndrome (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.63

BayesDel_noAF

Pathogenic

0.42

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

Eigen

Pathogenic

1.2

Eigen_PC

Pathogenic

1.1

FATHMM_MKL

Pathogenic

1.0

PhyloP100

9.5

GERP RS

5.5

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

2.8

Mutation Taster

=0/100

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.94

SpliceAI score (max)

1.0

Details are displayed if max score is > 0.2

DS_DL_spliceai

1.0

Position offset: -1

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over