chr3-37001050-T-G

Variant names:

• chr3-37001050-T-G
• rs4647220
• NM_000249.4:c.303T>G

Variant summary

Our verdict is Benign. Variant got -8 ACMG points: 8P and 16B. PVS1 BP6_Very_Strong BS1 BS2

The NM_001167617.3(MLH1):​c.12+2T>G variant causes a splice donor, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00109 in 1,585,538 control chromosomes in the GnomAD database, including 29 homozygotes. In-silico tool predicts a benign outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely benign (★★★).

• Frequency:
  • Genomes: 𝑓 0.00074 (4 hom., cov: 32)
  • Exomes 𝑓: 0.0011 (25 hom.)
• Consequence: MLH1 NM_001167617.3 splice_donor, intron
• Clinical Significance: Likely benign reviewed by expert panel B:17 O:1
• Conservation: PhyloP100: -0.441

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]

ACMG classification

Verdict is Benign. Variant got -8 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 9.8, offset of 5, new splice context is: gagGTaagc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• BP6: Variant 3-37001050-T-G is Benign according to our data. Variant chr3-37001050-T-G is described in ClinVar as [Likely_benign]. Clinvar id is 90140.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr3-37001050-T-G is described in Lovd as [Likely_benign]. Variant chr3-37001050-T-G is described in Lovd as [Benign].
• BS1: Variant frequency is greater than expected in population sas. gnomad4 allele frequency = 0.000742 (113/152280) while in subpopulation SAS AF= 0.0226 (109/4824). AF 95% confidence interval is 0.0192. There are 4 homozygotes in gnomad4. There are 79 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd4 at 4 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.303T>G	p.Gly101Gly	synonymous_variant	Exon 3 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.303T>G	p.Gly101Gly	synonymous_variant	Exon 3 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes AF: 0.000736 AC: 112 AN: 152162 Hom.: 4 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000131

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.0224

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00249 AC: 627 AN: 251344 Hom.: 11 AF XY: 0.00306 AC XY: 416 AN XY: 135846

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.0000868

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.0200

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00163

GnomAD4 exome AF: 0.00113 AC: 1621 AN: 1433258 Hom.: 25 Cov.: 26 AF XY: 0.00157 AC XY: 1122 AN XY: 714766

Gnomad4 AFR exome AF: 0.0000609

Gnomad4 AMR exome AF: 0.0000448

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000507

Gnomad4 SAS exome AF: 0.0174

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000101

Gnomad4 OTH exome AF: 0.00176

GnomAD4 genome AF: 0.000742 AC: 113 AN: 152280 Hom.: 4 Cov.: 32 AF XY: 0.00106 AC XY: 79 AN XY: 74454

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.000131

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.0226

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000897 Hom.: 0

Bravo AF: 0.0000982

ExAC AF: 0.00273 AC: 331

Asia WGS AF: 0.00925 AC: 32 AN: 3472

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Likely benign

Submissions summary: Benign:17 Other:1

Revision: reviewed by expert panel

Submissions by phenotype

not specified Benign:5 Other:1

Benign, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Dec 06, 2021	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Aug 15, 2014	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
not provided, no classification provided	reference population	ITMI	Sep 19, 2013	- -
Likely benign, criteria provided, single submitter	clinical testing	Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital	Mar 04, 2025	- -
Likely benign, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Jun 15, 2016	- -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -

not provided Benign:3

Likely benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Feb 04, 2022	- -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	May 20, 2016	Variant summary: The c.303T>G (p.Gly101=) in MLH1 gene is a synonymous change that involves a non-conserved nucleotide. 5/5 programs in Alamut predict that this variant does not affect normal splicing which was supported by a RNA-based functional assay by Thompson et al (2012). The variant is present in the control population dataset of ExAC at frequency of 0.0027 (331/121138) predominantly in individuals of South Asian descent (0.02; 329/16482 chrs) including 5 homozygous occurrences, suggesting that it is a polymorphism mainly found in South Asian population. The variant of interest been reported in affected individuals in whom either another known pathogenic variant was identified (Internal LCA data) or ICH results pointed out mutation(s) in other MMR genes (Mangold, 2007). In addition, the variant is cited as Benign/Likely Benign by reputable databases/clinical laboratories. Taking together, the variant is classified as Benign. -
Likely benign, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -

Colorectal cancer, hereditary nonpolyposis, type 2 Benign:2

Likely benign, criteria provided, single submitter	clinical testing	KCCC/NGS Laboratory, Kuwait Cancer Control Center	Jul 07, 2023	- -
Likely benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Feb 22, 2019	This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. The evidence from the literature, in combination with allele frequency data from public databases where available, was sufficient to determine this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

Lynch syndrome Benign:2

Likely benign, reviewed by expert panel	research	International Society for Gastrointestinal Hereditary Tumours (InSiGHT)	Sep 05, 2013	Synonymous substitution with no effect on splicing & MAF 0.01-1% -
Benign, no assertion criteria provided	clinical testing	Department of Pathology and Laboratory Medicine, Sinai Health System	-	The MLH1 p.Gly101Gly was identified in 1 of 20 proband chromosomes (frequency: 0.05) from individuals with Muir-Torre syndrome (Mangold 2007). The variant was also identified in dbSNP (ID: rs4647220) “With other allele”, in the 1000 Genomes Project in 32 of 5000 chromosomes (frequency: 0.0064) and in the Exome Aggregation Consortium (ExAC) database (released Jan 13, 2015) in 336 of 16482 chromosomes (frequency: 0.02) (or 329 individuals and 5 homozygous individuals) from a population of South Asian individuals, increasing the likelihood that this may be a low frequency benign variant in certain populations of origin. The variant was also identified in Clinvitae database (2x), “Mismatch Repair Genes Variant Database”, InSiGHT Colon Cancer Gene Variant Database (2X), the ClinVar database (classified as a likely benign by an expert panel), and UMD (1X as an unknown variant). The p.Gly101Gly variant is not expected to have clinical significance because it does not result in a change of amino acid and is not located in a known consensus splice site. The variant occurs outside of the splicing consensus sequence, 4th base from the 5' splice region, and 3 of 5 in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer, HumanSpliceFinder) predict a greater than 10% difference in splicing leading to the loss of a predicted splice site at a non-consensus splice site location; we cannot eliminate the possibility that an exon splice enhancer was modified and may lead to abnormal splicing or creation of a cryptic splice site however this information is not predictive enough to assume pathogenicity. Thompson et al. (2013) assessed MMR (mismatch repair) variants using multifactorial analysis, prior probabilities and likelihood ratios, as well as in vitro splicing assays and found the variant to be Class 3, uncertain significance, and having wildtype splicing. The identification of this variant in an individual with a co-occurring pathogenic variant (MSH2, c.1-?_366+?del) from our laboratory increases the likelihood this variant does not have clinical significance. In summary, based on the above information, this variant is classified as benign. -

Hereditary cancer-predisposing syndrome Benign:2

Benign, criteria provided, single submitter	clinical testing	Ambry Genetics	Oct 23, 2019	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. -
Benign, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Apr 23, 2015	- -

Breast and/or ovarian cancer Benign:1

Benign, criteria provided, single submitter

clinical testing

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Sep 14, 2021

- -

Muir-Torré syndrome Benign:1

Benign, criteria provided, single submitter

clinical testing

KCCC/NGS Laboratory, Kuwait Cancer Control Center

Feb 01, 2025

- -

Hereditary nonpolyposis colorectal neoplasms Benign:1

Benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 02, 2025

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.56	T
BayesDel_noAF	Benign	-0.56
CADD	Benign	13
DANN	Benign	0.72
Eigen	Benign	-0.35
Eigen_PC	Benign	-0.42
FATHMM_MKL	Benign	0.49	N
ClinPred		0.017	T
GERP RS		-6.8

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

LitVar

Other links and lift over

dbSNP: rs4647220; hg19: chr3-37042541;