rs863224068

Positions:

• chr1-11992690-G-A
• chr1-11992690-G-T

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate PP5_Very_Strong

The NM_014874.4(MFN2):​c.311G>A​(p.Arg104Gln) variant causes a missense, splice region 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. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R104L) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 31)
• Consequence: MFN2 NM_014874.4 missense, splice_region
• Scores: Splicing: ADA: 0.9995
• Clinical Significance: Likely 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]

MFN2 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 17 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 chr1-11992689-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 2281.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), MFN2. . Gene score misZ 1.6575 (greater than the threshold 3.09). Trascript score misZ 3.2174 (greater than threshold 3.09). GenCC has associacion of gene with 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, 0.901
• PP5: Variant 1-11992690-G-A is Pathogenic according to our data. Variant chr1-11992690-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 637289.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MFN2	NM_014874.4	c.311G>A	p.Arg104Gln	missense_variant, splice_region_variant	4/19	ENST00000235329.10	NP_055689.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MFN2	ENST00000235329.10	c.311G>A	p.Arg104Gln	missense_variant, splice_region_variant	4/19	1	NM_014874.4	ENSP00000235329.5

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 31

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	May 27, 2022	Reported in the heterozygous state in an individual with CMT2, however this individual also carried a heterozygous variant in the GDAP1 gene (Bacquet et al., 2018); Observed with a second MFN2 variant in unrelated patients in published literature, but it is not known whether the variants occurred on the same (in cis) or on different (in trans) chromosomes in some cases (Bombelli et al., 2014; Hoebeke et al., 2018); De novo variant with confirmed parentage in unrelated patients referred for genetic testing at GeneDx and in the published literature (Zhu et al., 2021); however, the reported clinical features are only partially consistent with the features typically observed in individuals with pathogenic variants in this gene; Fibroblast microscopy studies performed on patient cells harboring R104Q and a second MFN2 variant on different (in trans) chromosomes suggest higher mitochondrial fusion with long over-fused mitochondria and higher number of branch points compared to controls (Codron et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 30340945, 33971972, 27706887, 30373780, 24957169) -
Likely pathogenic, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Dec 01, 2020	- -

Charcot-Marie-Tooth disease Uncertain:1

Uncertain significance, no assertion criteria provided

literature only

Inherited Neuropathy Consortium

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.41	D
BayesDel_noAF	Pathogenic	0.35
CADD	Pathogenic	35
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.85	D;D
Eigen	Uncertain	0.66
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.96	D;.
M_CAP	Uncertain	0.27	D
MetaRNN	Pathogenic	0.90	D;D
MetaSVM	Pathogenic	0.88	D
MutationAssessor	Uncertain	2.5	M;M
PrimateAI	Pathogenic	0.82	D
PROVEAN	Uncertain	-3.7	D;D
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D;D
Sift4G	Benign	0.063	T;T
Polyphen		1.0	D;D
Vest4		0.82
MutPred		0.60		Loss of MoRF binding (P = 0.0158);Loss of MoRF binding (P = 0.0158);
MVP		0.95
MPC		1.9
ClinPred		0.99	D
GERP RS		5.5
Varity_R		0.95
gMVP		0.92

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.89
SpliceAI score (max)		0.020		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: rs863224068; hg19: chr1-12052747; COSMIC: COSV52422700; COSMIC: COSV52422700;