NM_000249.4:c.278G>T

Variant names:

• chr3-37001025-G-T
• NM_000249.4:c.278G>T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PM5

The NM_000249.4(MLH1):​c.278G>T​(p.Ser93Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. S93G) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.03

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 Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-37001024-A-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.278G>T	p.Ser93Ile	missense_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.278G>T	p.Ser93Ile	missense_variant	Exon 3 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1

Dec 06, 2022

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.S93I variant (also known as c.278G>T), located in coding exon 3 of the MLH1 gene, results from a G to T substitution at nucleotide position 278. The serine at codon 93 is replaced by isoleucine, an amino acid with dissimilar properties. This amino acid position is not well 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.17
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.18
CADD	Benign	20
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.91	D
Eigen	Benign	-0.53
Eigen_PC	Benign	-0.71
FATHMM_MKL	Benign	0.086	N
LIST_S2	Uncertain	0.97	D
M_CAP	Uncertain	0.14	D
MetaRNN	Uncertain	0.51	D
MetaSVM	Benign	-0.74	T
MutationAssessor	Pathogenic	3.7	H
PrimateAI	Benign	0.34	T
PROVEAN	Uncertain	-4.4	D
REVEL	Uncertain	0.60
Sift	Uncertain	0.012	D
Sift4G	Uncertain	0.019	D
Polyphen		0.14	B
Vest4		0.56
MutPred		0.54		Loss of disorder (P = 0.0244);
MVP		0.98
MPC		0.21
ClinPred		0.96	D
GERP RS		-3.4
Varity_R		0.42
gMVP		0.59

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr3-37042516;