NM_000251.3:c.1661G>C

Variant names:

• chr2-47466808-G-C
• rs63750597
• NM_000251.3:c.1661G>C

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000251.3(MSH2):​c.1661G>C​(p.Ser554Thr) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S554R) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: MSH2 NM_000251.3 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic reviewed by expert panel P:4 U:2
• Conservation: PhyloP100: 5.96
• Publications: 14 publications found

Genes affected

MSH2 (HGNC:7325): (mutS homolog 2) This locus is frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). When cloned, it was discovered to be a human homolog of the E. coli mismatch repair gene mutS, consistent with the characteristic alterations in microsatellite sequences (RER+ phenotype) found in HNPCC. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Apr 2012]

MSH2 Gene-Disease associations (from GenCC):

• Lynch syndrome

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, ClinGen, Orphanet
• Lynch syndrome 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Ambry Genetics
• Muir-Torre syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet, G2P
• mismatch repair cancer syndrome 1

  Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• mismatch repair cancer syndrome 2

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
• ovarian cancer

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• malignant pancreatic neoplasm

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• prostate cancer

  Inheritance: AD Classification: MODERATE Submitted by: Ambry Genetics
• rhabdomyosarcoma

  Inheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
• breast cancer

  Inheritance: AD Classification: NO_KNOWN Submitted by: Ambry Genetics
• hereditary breast carcinoma

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 16 benign, 29 uncertain in NM_000251.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-47466807-A-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 1403555.
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 2-47466808-G-C is Pathogenic according to our data. Variant chr2-47466808-G-C is described in ClinVar as Pathogenic. ClinVar VariationId is 90724.Status of the report is reviewed_by_expert_panel, 3 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MSH2	NM_000251.3	c.1661G>C	p.Ser554Thr	missense_variant, splice_region_variant	Exon 10 of 16	ENST00000233146.7	NP_000242.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MSH2	ENST00000233146.7	c.1661G>C	p.Ser554Thr	missense_variant, splice_region_variant	Exon 10 of 16	1	NM_000251.3	ENSP00000233146.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4 Uncertain:2

Revision: reviewed by expert panel

Submissions by phenotype

not provided Pathogenic:1 Uncertain:1

Mar 13, 2025

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Exonic splice site variant demonstrated to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease (PMID: 15365996); Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 15365996, 31569399, 16476474, 33357406, 21778331, 34897210, 23523604, 24362816)

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

Lynch syndrome 1 Pathogenic:1

Aug 03, 2023

Myriad Genetics, Inc.

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered likely pathogenic. mRNA analysis has demonstrated abnormal mRNA splicing occurs [PMID: 15365996].

Lynch syndrome Pathogenic:1

Sep 05, 2013

International Society for Gastrointestinal Hereditary Tumours (InSiGHT)

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: research

Variant causes splicing aberration (full inactivation of variant allele)

Hereditary cancer-predisposing syndrome Pathogenic:1

Mar 20, 2025

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1661G>C pathogenic mutation (also known as p.S554T), located in coding exon 10 of the MSH2 gene, results from a G to C substitution at nucleotide position 1661. The amino acid change results in serine to threonine at codon 554, an amino acid with similar properties. However, this change occurs in the last base pair of coding exon 10, which makes it likely to have some effect on normal mRNA splicing. This mutation was first described in a German patient meeting Amsterdam I criteria, who had rectal cancer at 59 years of age and whose tumor was absent for MSH2 on IHC and showed high microsatellite instability. Family history included a mother and brother with colon cancer at 43 and 31 years of age, respectively. RT-PCR analysis of mRNA revealed skipping of exon 10, which the authors concluded established the pathogenicity of this alteration (Kruger S et al. Hum Mutat. 2004;24(4):351-2). One study described another mutation at this nucleotide position (c.1661G>A), which was detected in a large Lynch syndrome family (44 individuals tested). The proband was diagnosed with cancer of the colon-rectum, rectum-sigma at 47 years of age, and his tumor was absent for MSH2/MSH6 and showed high microsatellite instability. Functional analysis showed that this mutation abolished the consensus splice donor site and resulted in the deletion of 81 bp in the mRNA (Perez-Cabornero L et al. Eur J Cancer. 2009 May;45(8):1485-93). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). This nucleotide position is highly conserved in available vertebrate species. This amino acid position is well conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice donor site. In addition, the in silico prediction for this alteration is inconclusive. Based on the supporting evidence, this variant is interpreted as a disease-causing mutation.

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

May 19, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. This sequence change replaces serine, which is neutral and polar, with threonine, which is neutral and polar, at codon 554 of the MSH2 protein (p.Ser554Thr). This variant also falls at the last nucleotide of exon 10, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Lynch syndrome (PMID: 15365996). ClinVar contains an entry for this variant (Variation ID: 90724). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant  is likely to be tolerated. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this missense change is associated with altered splicing resulting in skipping of exon 10 (PMID: 15365996).

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.067
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
CADD	Pathogenic	27
DANN	Uncertain	0.98
DEOGEN2	Uncertain	0.51	D;.;.;.
Eigen	Uncertain	0.24
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D;D;D;D
M_CAP	Uncertain	0.085	D
MetaRNN	Uncertain	0.54	D;D;D;D
MetaSVM	Uncertain	-0.038	T
MutationAssessor	Benign	2.0	M;.;.;.
PhyloP100		6.0
PrimateAI	Uncertain	0.58	T
PROVEAN	Benign	-1.6	N;N;.;N
REVEL	Uncertain	0.61
Sift	Benign	0.15	T;T;.;T
Sift4G	Benign	0.37	T;T;.;T
Vest4		0.67
ClinPred		0.87	D
GERP RS		5.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.66
gMVP		0.30
Mutation Taster		=1/99	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.97		Position offset: 0

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

Other links and lift over

dbSNP: rs63750597; hg19: chr2-47693947;