chr1-161306911-T-C

Position:

• chr1-161306911-T-C

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PM5 PP3_Moderate PP5_Very_Strong

The NM_000530.8(MPZ):​c.245A>G​(p.Tyr82Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 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. Y82H) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 28)
• Consequence: MPZ NM_000530.8 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4 U:1
• Conservation: PhyloP100: 2.31

Genes affected

MPZ (HGNC:7225): (myelin protein zero) This gene is specifically expressed in Schwann cells of the peripheral nervous system and encodes a type I transmembrane glycoprotein that is a major structural protein of the peripheral myelin sheath. The encoded protein contains a large hydrophobic extracellular domain and a smaller basic intracellular domain, which are essential for the formation and stabilization of the multilamellar structure of the compact myelin. Mutations in this gene are associated with autosomal dominant form of Charcot-Marie-Tooth disease type 1 (CMT1B) and other polyneuropathies, such as Dejerine-Sottas syndrome (DSS) and congenital hypomyelinating neuropathy (CHN). A recent study showed that two isoforms are produced from the same mRNA by use of alternative in-frame translation termination codons via a stop codon readthrough mechanism. [provided by RefSeq, Oct 2015]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 12 uncertain in NM_000530.8
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-161306912-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 41017.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.93
• PP5: Variant 1-161306911-T-C is Pathogenic according to our data. Variant chr1-161306911-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 549681.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-161306911-T-C is described in Lovd as [Likely_pathogenic]. Variant chr1-161306911-T-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MPZ	NM_000530.8	c.245A>G	p.Tyr82Cys	missense_variant	3/6	ENST00000533357.5
MPZ	NM_001315491.2	c.245A>G	p.Tyr82Cys	missense_variant	3/6
MPZ	XM_017001321.3	c.275A>G	p.Tyr92Cys	missense_variant	3/6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MPZ	ENST00000533357.5	c.245A>G	p.Tyr82Cys	missense_variant	3/6	1	NM_000530.8	P1

Frequencies

GnomAD3 genomes Cov.: 28

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 28

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Charcot-Marie-Tooth disease Pathogenic:1 Uncertain:1

Pathogenic, criteria provided, single submitter	clinical testing	Molecular Genetics Laboratory, London Health Sciences Centre	-	- -
Uncertain significance, no assertion criteria provided	literature only	Inherited Neuropathy Consortium	-	- -

Peripheral neuropathy Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Kariminejad - Najmabadi Pathology & Genetics Center

Jul 10, 2021

- -

Charcot-Marie-Tooth disease dominant intermediate D Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Institute of Human Genetics, Cologne University

Apr 25, 2018

- -

Charcot-Marie-Tooth disease, type I Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 12, 2022

This sequence change replaces tyrosine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 82 of the MPZ protein (p.Tyr82Cys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Charcot-Marie-Tooth (CMT) disease type 1 and Déjérine-Sottas syndrome (PMID: 7505151, 9633821, 11545686, 11835375, 12402337, 26310628). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 549681). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. This variant disrupts the p.Tyr82 amino acid residue in MPZ. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 7505151, 11545686, 11835375, 12402337, 26310628). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.68	D
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.52
FATHMM_MKL	Uncertain	0.83	D
LIST_S2	Uncertain	0.94	D
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.93	D
MetaSVM	Uncertain	-0.090	T
MutationAssessor	Pathogenic	3.2	M
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.83	D
PROVEAN	Pathogenic	-8.0	D
REVEL	Pathogenic	0.68
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0040	D
Polyphen		1.0	D
Vest4		0.95
MutPred		0.71		Loss of phosphorylation at Y82 (P = 0.0348);
MVP		0.92
MPC		1.6
ClinPred		1.0	D
GERP RS		4.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.95
gMVP		1.0

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: rs1553259707; hg19: chr1-161276701;