NM_000530.8:c.662C>T

Variant names:

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1PM2PM5

The NM_000530.8(MPZ):c.662C>T(p.Ala221Val) variant causes a missense change. The variant allele was found at a frequency of 0.00000658 in 152,010 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A221T) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 31)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Failed GnomAD Quality Control

Consequence

MPZ
NM_000530.8 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1O:1

Conservation

PhyloP100: 5.12

Variant links:

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]

MPZ links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 10 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 chr1-161305962-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MPZ	NM_000530.8 link	c.662C>T	p.Ala221Val	missense_variant	Exon 6 of 6	ENST00000533357.5	NP_000521.2	P25189-1
MPZ	NM_001315491.2 link	c.662C>T	p.Ala221Val	missense_variant	Exon 6 of 6		NP_001302420.1	P25189A0A5F9ZI26
MPZ	XM_017001321.3 link	c.675+147C>T		intron_variant	Intron 5 of 5		XP_016856810.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MPZ	ENST00000533357.5 link	c.662C>T	p.Ala221Val	missense_variant	Exon 6 of 6	1	NM_000530.8	ENSP00000432943.1		P25189-1

Frequencies

GnomAD3 genomes

AF:

0.00000658

AC:

AN:

152010

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD4 exome

Data not reliable, filtered out with message: AS_VQSR

AF:

6.84e-7

AC:

AN:

1461770

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727204

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

8.99e-7

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000658

AC:

AN:

152010

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74238

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1Other:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Charcot-Marie-Tooth disease, type I

Uncertain:1

Dec 27, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 221 of the MPZ protein (p.Ala221Val). This variant is present in population databases (no rsID available, gnomAD 0.007%). This variant has not been reported in the literature in individuals affected with MPZ-related conditions. ClinVar contains an entry for this variant (Variation ID: 462799). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Charcot-Marie-Tooth disease type 1B;C1843075:Charcot-Marie-Tooth disease dominant intermediate D;C1843153:Charcot-Marie-Tooth disease type 2J;C3888087:Charcot-Marie-Tooth disease type 2I

Other:1

GenomeConnect - Invitae Patient Insights Network

Significance: not provided

Review Status: no classification provided

Collection Method: phenotyping only

Variant interpreted as Uncertain significance and reported on 09-18-2017 by Invitae. GenomeConnect-Invitae Patient Insights Network assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. Registry team members make no attempt to reinterpret the clinical significance of the variant. Phenotypic details are available under supporting information. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.66

BayesDel_addAF

Pathogenic

0.28

BayesDel_noAF

Pathogenic

0.17

CADD

Pathogenic

DANN

Uncertain

1.0

DEOGEN2

Benign

0.41

T;D

Eigen

Uncertain

0.36

Eigen_PC

Uncertain

0.44

FATHMM_MKL

Uncertain

0.77

LIST_S2

Benign

0.84

T;T

MetaRNN

Uncertain

0.55

D;D

MetaSVM

Benign

-0.78

MutationAssessor

Benign

0.97

L;.

PrimateAI

Uncertain

0.78

PROVEAN

Benign

-1.4

N;D

REVEL

Pathogenic

0.75

Sift

Pathogenic

0.0

D;D

Sift4G

Pathogenic

0.0

D;D

Polyphen

1.0

D;.

Vest4

0.46

MutPred

0.64

Gain of sheet (P = 0.1208);.;

MVP

0.64

MPC

1.2

ClinPred

0.97

GERP RS

5.1

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.59

gMVP

0.49

Splicing

Name

Calibrated prediction

Score

Prediction

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over