14-75047634-AT-ATT

Variant names:

• chr14-75047634-A-AT
• rs767782578
• NM_001040108.2:c.2021dupA

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 8P and 4B. PVS1 BS2

The NM_001040108.2(MLH3):​c.2021dupA​(p.Asn674LysfsTer13) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000806 in 1,613,412 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: MLH3 NM_001040108.2 frameshift
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 0.505

Genes affected

MLH3 (HGNC:7128): (mutL homolog 3) This gene is a member of the MutL-homolog (MLH) family of DNA mismatch repair (MMR) genes. MLH genes are implicated in maintaining genomic integrity during DNA replication and after meiotic recombination. The protein encoded by this gene functions as a heterodimer with other family members. Somatic mutations in this gene frequently occur in tumors exhibiting microsatellite instability, and germline mutations have been linked to hereditary nonpolyposis colorectal cancer type 7 (HNPCC7). Several alternatively spliced transcript variants have been identified, but the full-length nature of only two transcript variants has been determined. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• BS2: High AC in GnomAdExome4 at 9 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH3	NM_001040108.2	c.2021dupA	p.Asn674LysfsTer13	frameshift_variant	Exon 2 of 13	ENST00000355774.7	NP_001035197.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH3	ENST00000355774.7	c.2021dupA	p.Asn674LysfsTer13	frameshift_variant	Exon 2 of 13	5	NM_001040108.2	ENSP00000348020.2
MLH3	ENST00000380968.6	c.2021dupA	p.Asn674LysfsTer13	frameshift_variant	Exon 2 of 12	1		ENSP00000370355.3
MLH3	ENST00000556257.5	c.2021dupA	p.Asn674LysfsTer13	frameshift_variant	Exon 2 of 7	5		ENSP00000451540.1

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 151944 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000726

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000400 AC: 1 AN: 250086 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135188

Gnomad AFR exome AF: 0.0000616

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461468 Hom.: 0 Cov.: 35 AF XY: 0.00000550 AC XY: 4 AN XY: 727000

Gnomad4 AFR exome AF: 0.0000299

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: 0.00000630

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 151944 Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1 AN XY: 74210

Gnomad4 AFR AF: 0.0000726

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000252 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Nov 22, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2021dupA variant, located in coding exon 1 of the MLH3 gene, results from a duplication of A at nucleotide position 2021, causing a translational frameshift with a predicted alternate stop codon (p.N674Kfs*13). This alteration is expected to result in premature protein truncation or nonsense-mediated mRNA decay. The evidence for this gene-disease relationship is limited; therefore, the clinical significance of this alteration is unclear. -

Colorectal cancer, hereditary nonpolyposis, type 7 Uncertain:1

Feb 03, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Asn674Lysfs*13) in the MLH3 gene. It is expected to result in an absent or disrupted protein product. However, the current clinical and genetic evidence is not sufficient to establish whether loss-of-function variants in MLH3 cause disease. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with MLH3-related conditions. ClinVar contains an entry for this variant (Variation ID: 410889). 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. -

Endometrial carcinoma Uncertain:1

May 16, 2023

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

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: rs767782578; hg19: chr14-75514337;