rs63750062

Positions:

• chr3-37042293-A-G
• chr3-37042293-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 6P and 1B. PM1 PM2 PM5 BP4

The ENST00000231790.8(MLH1):​c.1693A>G​(p.Ile565Val) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 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. I565F) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 ENST00000231790.8 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.70

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 5 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 16 uncertain in ENST00000231790.8
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-37042293-A-T is described in Lovd as [Pathogenic].
• BP4: Computational evidence support a benign effect (MetaRNN=0.35116646).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MLH1	NM_000249.4	c.1693A>G	p.Ile565Val	missense_variant	15/19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.1693A>G	p.Ile565Val	missense_variant	15/19	1	NM_000249.4	ENSP00000231790	P1

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 nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 19, 2019

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. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The valine amino acid residue is found in multiple mammalian species, suggesting that this missense change does not adversely affect protein function. These predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with MLH1-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces isoleucine with valine at codon 565 of the MLH1 protein (p.Ile565Val). The isoleucine residue is moderately conserved and there is a small physicochemical difference between isoleucine and valine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.074
BayesDel_addAF	Uncertain	0.11	D
BayesDel_noAF	Uncertain	-0.070
CADD	Benign	19
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.64	D;.;.;.;.;.
Eigen	Benign	-0.30
Eigen_PC	Benign	-0.12
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Benign	0.85	T;D;.;.;.;D
M_CAP	Benign	0.040	D
MetaRNN	Benign	0.35	T;T;T;T;T;T
MetaSVM	Benign	-0.41	T
MutationAssessor	Benign	0.88	L;.;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.64	T
PROVEAN	Benign	-0.84	N;N;N;N;N;N
REVEL	Uncertain	0.39
Sift	Benign	0.26	T;T;T;T;T;T
Sift4G	Benign	0.20	T;T;T;T;T;T
Polyphen		0.0	B;.;.;.;.;.
Vest4		0.49
MutPred		0.51		Gain of sheet (P = 0.0827);.;.;.;.;.;
MVP		0.94
MPC		0.058
ClinPred		0.45	T
GERP RS		3.1
Varity_R		0.12
gMVP		0.41

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.16		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: rs63750062; hg19: chr3-37083784;