1-12002034-G-C

Variant names:

• chr1-12002034-G-C
• rs879254011
• NM_014874.4:c.1091G>C

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_014874.4(MFN2):​c.1091G>C​(p.Arg364Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R364L) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: MFN2 NM_014874.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2 U:1
• Conservation: PhyloP100: 9.60

Genes affected

MFN2 (HGNC:16877): (mitofusin 2) This gene encodes a mitochondrial membrane protein that participates in mitochondrial fusion and contributes to the maintenance and operation of the mitochondrial network. This protein is involved in the regulation of vascular smooth muscle cell proliferation, and it may play a role in the pathophysiology of obesity. Mutations in this gene cause Charcot-Marie-Tooth disease type 2A2, and hereditary motor and sensory neuropathy VI, which are both disorders of the peripheral nervous system. Defects in this gene have also been associated with early-onset stroke. Two transcript variants encoding the same protein have been identified. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 19 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 8 uncertain in NM_014874.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-12002034-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 245944.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the MFN2 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 123 curated pathogenic missense variants (we use a threshold of 10). The gene has 23 curated benign missense variants. Gene score misZ: 1.6575 (below the threshold of 3.09). Trascript score misZ: 3.2174 (above the threshold of 3.09). GenCC associations: The gene is linked to Charcot-Marie-Tooth disease type 2A2, axonal hereditary motor and sensory neuropathy, hereditary motor and sensory neuropathy type 6, Charcot-Marie-Tooth disease, axonal, autosomal recessive, type 2a2b;, multiple symmetric lipomatosis, severe early-onset axonal neuropathy due to MFN2 deficiency.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.986
• PP5: Variant 1-12002034-G-C is Pathogenic according to our data. Variant chr1-12002034-G-C is described in ClinVar as [Pathogenic]. Clinvar id is 572157.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-12002034-G-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MFN2	NM_014874.4	c.1091G>C	p.Arg364Pro	missense_variant	Exon 11 of 19	ENST00000235329.10	NP_055689.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MFN2	ENST00000235329.10	c.1091G>C	p.Arg364Pro	missense_variant	Exon 11 of 19	1	NM_014874.4	ENSP00000235329.5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Charcot-Marie-Tooth disease type 2A2 Pathogenic:1

Jan 03, 2022

3billion

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant has been observed in multiple (>3) similarly affected unrelated individuals(PMID: 22492563, 20008656, 21508331, PS4_S). A different missense change at the same codon has been reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000002278,VCV000245944, PMID:16437557,17444508, PM5_M). In silico tool predictions suggest damaging effect of the variant on gene or gene product (REVEL: 0.918, 3CNET: 0.994, PP3_P). A missense variant is a common mechanism associated with Charcot-Marie-Tooth disease (PP2_P). It is not observed in the gnomAD v2.1.1 dataset (PM2_M). Therefore, this variant is classified as pathogenic according to the recommendation of ACMG/AMP guideline. -

Charcot-Marie-Tooth disease type 2 Pathogenic:1

Mar 30, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. A different missense substitution at this codon (p.Arg364Trp) has been determined to be pathogenic (PMID: 16437557, 16835246, 22492563, 21707411, 22206013, 21508331, 25802885, 28063088, 27549087, 25448007). This suggests that the arginine residue is critical for MFN2 protein function and that other missense substitutions at this position may also be pathogenic. 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 C0"). This variant has been reported to segregate with Charcot-Marie-Tooth disease, type 2 and optic atrophy in a family (PMID: 24957169) and has been reported in individuals affected with Charcot-Marie-Tooth disease, type 2 (PMID: 22492563, 20008656, 21508331). This variant is not present in population databases (ExAC no frequency). This sequence change replaces arginine with proline at codon 364 of the MFN2 protein (p.Arg364Pro). The arginine residue is highly conserved and there is a moderate physicochemical difference between arginine and proline. -

Charcot-Marie-Tooth disease Uncertain:1

-

Inherited Neuropathy Consortium

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.85	D;D
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D;.
M_CAP	Pathogenic	0.43	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.0	M;M
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-5.3	D;D
REVEL	Pathogenic	0.92
Sift	Uncertain	0.0020	D;D
Sift4G	Uncertain	0.012	D;D
Polyphen		1.0	D;D
Vest4		0.98
MutPred		0.90		Loss of MoRF binding (P = 4e-04);Loss of MoRF binding (P = 4e-04);
MVP		0.99
MPC		2.1
ClinPred		0.99	D
GERP RS		5.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.98
gMVP		0.98

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: rs879254011; hg19: chr1-12062091;