M-14482-C-G

Variant names:

• chrM-14482-C-G
• rs199476108
• ENST00000361681.2:c.192G>C

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PS1 PM5 PP3 PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The m.14482C>G (p.M64I) variant in MT-ND6 has been reported in one proband from an extended consanguineous kindred with primary mitochondrial disease. The predominant feature in this family was bilateral optic atrophy consistent with Leber Hereditary Optic Neuropathy (LHON). The variant was present at homoplasmy in affected and unaffected individuals from this family and, when affected, the age of onset was early adulthood (PMID:9443868). It appears some individuals from this family were reported multiple times (PMIDs: 21887510, 8742999). There are no reported de novo occurrences of this variant to our knowledge. The variant was homoplasmic in family members of the only reported proband, precluding consideration for segregation evidence. This variant is absent in the GenBank dataset, Helix dataset, and gnomAD v3.1.2 (PM2_supporting). Another variant at this nucleotide position leading to the same amino acid change was classified as likely pathogenic by this expert panel, m.14482C>A (p.M64I, PS1). Furthermore, a different variant at this amino acid position leading to a different amino acid change is one of the most common causes of LHON and is a known pathogenic variant, m.14484T>C (p.M64V, PM5). The computational predictor APOGEE gives a consensus rating of pathogenic with a score of 0.96 (Min=0, Max=1), which predicts a damaging effect on gene function (PP3). There are no cybrid studies, single fiber studies, or other functional assays reported for this variant. In summary, this variant meets criteria to be classified as likely pathogenic for primary mitochondrial disease inherited in a mitochondrial manner. We note that one expert on this panel felt uncertain significance was a more appropriate classification given the only reported family was consanguineous and nuclear genetic etiologies were not assessed. This classification was approved by the NICHD/NINDS U24 ClinGen Mitochondrial Disease Variant Curation Expert Panel on July 11, 2022. Mitochondrial DNA-specific ACMG/AMP criteria applied (PMID:32906214): PM2_supporting, PS1, PM5, PP3. LINK:https://erepo.genome.network/evrepo/ui/classification/CA344824/MONDO:0044970/014

• Frequency: Mitomap GenBank: Absent
• Consequence: MT-ND6 ENST00000361681.2 missense
• Scores: Apogee2 Pathogenic 0.97
• Clinical Significance: Likely pathogenic reviewed by expert panel P:1 O:1 LHON,LHON
• Conservation: PhyloP100: -3.83
• Publications: 15 publications found

Genes affected

MT-ND6 (HGNC:7462): (mitochondrially encoded NADH dehydrogenase 6) Enables NADH dehydrogenase (ubiquinone) activity. Involved in mitochondrial electron transport, NADH to ubiquinone and mitochondrial respiratory chain complex I assembly. Predicted to be located in mitochondrial inner membrane. Implicated in Leber hereditary optic neuropathy; Leigh disease; and spinal muscular atrophy with lower extremity predominante 2B. [provided by Alliance of Genome Resources, Apr 2022]

TRNE (HGNC:7479): (mitochondrially encoded tRNA glutamic acid)

TRNE Gene-Disease associations (from GenCC):

• mitochondrial disease

  Inheritance: Mitochondrial Classification: DEFINITIVE Submitted by: ClinGen

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PS1: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PM5: For more information check the summary or visit ClinGen Evidence Repository.
• PP3: For more information check the summary or visit ClinGen Evidence Repository.

Variant Effect in Transcripts

ACMG analysis was done for transcript: ENST00000361681.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
There are no transcript annotations for this variant.

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MT-ND6	ENST00000361681.2	TSL:6	c.192G>C	p.Met64Ile	missense	Exon 1 of 1	ENSP00000354665.2
	MT-TE	ENST00000387459.1	TSL:6	n.*192G>C		downstream_gene	N/A

Frequencies

Mitomap GenBank The variant is not present, suggesting it is rare .

Mitomap

Disease(s): LHON,LHON

Status: Cfrm-[LP],Cfrm-[LP]

ClinVar

ClinVar submissions as Germline

Significance: Likely pathogenic

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
1	-	-	Mitochondrial disease (1)
-	-	-	Leber optic atrophy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
Apogee2	Pathogenic	0.97
Hmtvar	Pathogenic	0.79
AlphaMissense	Pathogenic	0.81
BayesDel_addAF	Benign	-0.26	T
DEOGEN2	Benign	0.33	T
LIST_S2	Benign	0.73	T
MutationAssessor	Uncertain	2.1	M
PhyloP100		-3.8
PROVEAN	Benign	-1.3	N
Sift	Uncertain	0.0060	D
Sift4G	Uncertain	0.0030	D
GERP RS		-0.73
Varity_R		0.47
Mutation Taster		=77/23	polymorphism

Other links and lift over

dbSNP: rs199476108; hg19: chrM-14483;