rs267607829

chr3-37028899-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000249.4(MLH1):c.1525C>T(p.Leu509Phe) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,870 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 4.36

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 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 15 uncertain in NM_000249.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.771

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MLH1	NM_000249.4	c.1525C>T	p.Leu509Phe	missense_variant	13/19	ENST00000231790.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MLH1	ENST00000231790.8	c.1525C>T	p.Leu509Phe	missense_variant	13/19	1	NM_000249.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251456 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135898

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461870 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727242

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

May 04, 2018

This sequence change replaces leucine with phenylalanine at codon 509 of the MLH1 protein (p.Leu509Phe). The leucine residue is highly conserved and there is a small physicochemical difference between leucine and phenylalanine. This variant is not present in population databases (ExAC no frequency). This variant has been reported in an individual with acute myeloid leukemia .  However, it is uncertain if the variant is of germline or somatic origin (PMID: 18227862). ClinVar contains an entry for this variant (Variation ID: 89760). Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C15"). 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 23, 2014

The p.L509F variant (also known as c.1525C>T), located in coding exon 13 of the MLH1 gene, results from a C to T substitution at nucleotide position 1525. The leucine at codon 509 is replaced by phenylalanine, an amino acid with highly similar properties. This variant was previously reported in the SNPDatabase as rs267607829. This variant was not reported in population-based cohorts in the following databases: NHLBI Exome Sequencing Project (ESP) and 1000 Genomes Project. To date, this alteration has been detected with an allele frequency of approximately 0.004% (greater than 25,000 alleles tested) in our clinical cohort. Based on protein sequence alignment, this amino acid position is highly 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 p.L509F remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.42
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.17
Cadd	Pathogenic	26
Dann	Pathogenic	1.0
DEOGEN2	Pathogenic	0.94	D;.;.;.;.;.;T;D
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.94	D;D;.;.;.;D;D;D
M_CAP	Pathogenic	0.29	D
MetaRNN	Pathogenic	0.77	D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.96	D
MutationAssessor	Pathogenic	3.0	M;.;.;.;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.58	T
PROVEAN	Uncertain	-3.8	D;D;D;D;D;D;D;D
REVEL	Pathogenic	0.69
Sift	Uncertain	0.0030	D;D;D;D;D;D;D;D
Sift4G	Uncertain	0.0060	D;D;D;D;D;D;D;D
Polyphen		1.0	D;.;.;.;.;.;.;.
Vest4		0.56
MutPred		0.41		Loss of disorder (P = 0.1374);.;.;.;.;.;.;.;
MVP		0.88
MPC		0.42
ClinPred		0.97	D
GERP RS		5.9
Varity_R		0.91
gMVP		0.73

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: rs267607829; hg19: chr3-37070390;