M-3249-G-A

Position:

• chrM-3249-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

Variant has been reported in ClinVar as Uncertain significance (★★★).

• Frequency: Mitomap GenBank: Absent
• Consequence: TRNL1 missense
• Scores: Mitotip Uncertain 11
• Clinical Significance: Uncertain significance reviewed by expert panel U:2 KSS
• Conservation: PhyloP100: 6.34

Genes affected

TRNL1 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: No frequency data in Mitomap. Probably very rare.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TRNL1	unassigned_transcript_4789	c.20G>A	p.Gly7Asp	missense_variant	1/1
RNR2	unassigned_transcript_4788	n.*20G>A		downstream_gene_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt

Frequencies

GnomAD4 exome Cov.: 0

We have no GnomAD4 genomes data on this position. Probably position not covered by the project.

Mitomap

KSS

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: reviewed by expert panel

Submissions by phenotype

Mitochondrial disease Uncertain:1

Uncertain significance, reviewed by expert panel

curation

ClinGen Mitochondrial Disease Nuclear and Mitochondrial Variant Curation Expert Panel, ClinGen

Apr 22, 2024

The m.3249G>A variant in MT-TL1 has been reported in one individual to date, in a man with progressive vision loss, hearing loss, myopathy, and ragged red and COX-negative fibers, whose presentation was reminiscent of Kearns Sayre syndrome (PMID: 11448301). The variant was present at 85% heteroplasmy in skeletal muscle and 45% in leukocytes in the proband, 5% in the blood of the healthy mother, and was undetectable in blood from a healthy sister (PP1). This variant is absent in the GenBank dataset, Helix dataset, and gnomAD v3.1.2 (PM2_supporting). Computational predictors are conflicting (MitoTIP: 39.3%; HmtVAR: 0.45). There are no cybrids or single fiber studies reported on this variant, however two processing studies have shown termination blockage (PMID: 20550934) and RNAseP binding interference (PMID: 33380464), and this variant was also found to negatively impact 5' end cleavage and m1A9 methylation (PMID: 33380464; PS3_supporting). In summary, this variant meets criteria to be classified as uncertain significance for primary mitochondrial disease inherited in a mitochondrial manner. This classification was approved by the NICHD/NINDS U24 ClinGen Mitochondrial Disease Variant Curation Expert Panel on April 22, 2024. Mitochondrial DNA-specific ACMG/AMP criteria applied (PMID: 32906214): PP1, PM2_supporting, PS3_supporting. -

Kearns-Sayre syndrome Uncertain:1

Uncertain significance, no assertion criteria provided

literature only

OMIM

Jun 11, 2010

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
Mitotip	Uncertain	11
Hmtvar	Pathogenic	0.45

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs199474667; hg19: chrM-3250;