chr1-161306414-C-T

Position:

• chr1-161306414-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PS1_Very_Strong PM1 PM2 PM5 PP3_Moderate PP5_Moderate

The ENST00000533357.5(MPZ):​c.499G>A​(p.Gly167Arg) 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 Pathogenic (★). Another nucleotide change resulting in same amino acid change has been previously reported as Pathogenicin ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G167A) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 31)
• Consequence: MPZ ENST00000533357.5 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1 U:1 O:1
• Conservation: PhyloP100: 1.68

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 18 ACMG points.

• PS1: Transcript ENST00000533357.5 (MPZ) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar as 14170
• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in ENST00000533357.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.881
• PP5: Variant 1-161306414-C-T is Pathogenic according to our data. Variant chr1-161306414-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 208149.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr1-161306414-C-T is described in Lovd as [Pathogenic]. Variant chr1-161306414-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MPZ	NM_000530.8	c.499G>A	p.Gly167Arg	missense_variant	4/6	ENST00000533357.5	NP_000521.2
MPZ	NM_001315491.2	c.499G>A	p.Gly167Arg	missense_variant	4/6		NP_001302420.1
MPZ	XM_017001321.3	c.529G>A	p.Gly177Arg	missense_variant	4/6		XP_016856810.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MPZ	ENST00000533357.5	c.499G>A	p.Gly167Arg	missense_variant	4/6	1	NM_000530.8	ENSP00000432943	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1 Uncertain:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 24, 2021

This missense change has been observed in individual(s) with Dejerine-Sottas disease (PMID: 7506095, 10399750, 12242557). In at least one individual the variant was observed to be de novo. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 167 of the MPZ protein (p.Gly167Arg). This variant is also known as p.Gly138Arg. For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. Experimental studies have shown that this missense change affects MPZ function (PMID: 29687021). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 208149). -

Charcot-Marie-Tooth disease Uncertain:1

Uncertain significance, no assertion criteria provided

literature only

Inherited Neuropathy Consortium

-

- -

Charcot-Marie-Tooth disease type 1B Other:1

not provided, no classification provided

literature only

GeneReviews

-

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.43
CADD	Pathogenic	32
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.74	D
Eigen	Uncertain	0.51
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Benign	0.83	T
M_CAP	Uncertain	0.26	D
MetaRNN	Pathogenic	0.88	D
MetaSVM	Pathogenic	0.87	D
MutationAssessor	Benign	1.6	L
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.69	T
PROVEAN	Uncertain	-3.0	D
REVEL	Pathogenic	0.71
Sift	Uncertain	0.011	D
Sift4G	Uncertain	0.058	T
Polyphen		1.0	D
Vest4		0.96
MutPred		0.61		Gain of MoRF binding (P = 0.0404);
MVP		1.0
MPC		1.4
ClinPred		1.0	D
GERP RS		5.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.44
gMVP		0.98

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs121913586; hg19: chr1-161276204;