rs879254038

Variant names:

• chr1-161306800-T-C
• rs879254038
• NM_000530.8:c.356A>G

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP5

The NM_000530.8(MPZ):​c.356A>G​(p.Tyr119Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,872 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 29)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: MPZ NM_000530.8 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:7 U:2
• Conservation: PhyloP100: 0.620

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 Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a hotspot region, there are 9 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 16 uncertain in NM_000530.8
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-161306800-T-C is Pathogenic according to our data. Variant chr1-161306800-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 245997.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=3, Uncertain_significance=1, Pathogenic=4}. Variant chr1-161306800-T-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MPZ	NM_000530.8	c.356A>G	p.Tyr119Cys	missense_variant	Exon 3 of 6	ENST00000533357.5	NP_000521.2
MPZ	NM_001315491.2	c.356A>G	p.Tyr119Cys	missense_variant	Exon 3 of 6		NP_001302420.1
MPZ	XM_017001321.3	c.386A>G	p.Tyr129Cys	missense_variant	Exon 3 of 6		XP_016856810.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MPZ	ENST00000533357.5	c.356A>G	p.Tyr119Cys	missense_variant	Exon 3 of 6	1	NM_000530.8	ENSP00000432943.1

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461872 Hom.: 0 Cov.: 34 AF XY: 0.00000413 AC XY: 3 AN XY: 727234

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: 0.00000360

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 29

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:7 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:4

Mar 26, 2025

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Has been reported previously in at least two families with adult-onset Charcot-Marie-Tooth (CMT) disease, with some individuals also exhibiting hearing loss (PMID: 26310628, 10764043); Not observed at significant frequency in large population cohorts (gnomAD); Missense variants in this gene are a common cause of disease and they are underrepresented in the general population; In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 26310628, 10764043, 29687021, 33179255, 34210210, 34060689, 37581289, 36203352, 20461396, 28902413) -

Oct 01, 2018

CeGaT Center for Human Genetics Tuebingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 15, 2021

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 11, 2022

Athena Diagnostics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). This variant associates with disease in multiple families. Computational tools predict that this variant is damaging. The variant is located in a region that is considered important for protein function and/or structure. -

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

Jun 17, 2024

Institute of Immunology and Genetics Kaiserslautern

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

ACMG Criteria: PS3, PM1, PP1, PM2_P, PP5; Variant was found in heterozygous state -

Feb 02, 2022

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Likely pathogenic. Following criteria are met: 0103 - Loss of function and gain of function are known mechanisms of disease in this gene and are associated with Charcot-Marie-Tooth disease dominant intermediate D (MIM#607791), Charcot-Marie-Tooth disease, type 1B (MIM#118200), Charcot-Marie-Tooth disease, type 2I (MIM#607677), Charcot-Marie-Tooth disease, type 2J (MIM#607736), Dejerine-Sottas disease (MIM#145900), congenital hypomyelinating neuropathy 2 (MIM#618184), and Roussy-Levy syndrome (MIM#180800) (OMIM). Loss of function is associated with NMD-predicted variants while gain of function is associated with missense and protein truncation variants (PMIDs: 16495463, 30239779). (I) 0108 - This gene is associated with both recessive and dominant disease. Most conditions associated with this gene are dominantly inherited; however Dejerine-Sottas disease is also caused by biallelic variants (OMIM). (I) 0115 - Variants in this gene are known to have variable expressivity (PMIDs: 17030746, 30239779). (I) 0200 - Variant is predicted to result in a missense amino acid change from tyrosine to cysteine. (I) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0502 - Missense variant with conflicting in silico predictions and uninformative conservation. (I) 0600 - Variant is located in the annotated Ig-like V-type extracellular domain (UniProt). (I) 0705 - No comparable missense variants have previous evidence for pathogenicity. (I) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been identified in three families with adult-onset Charcot-Marie-Tooth disease and has been classified as pathogenic by clinical diagnostic laboratories (ClinVar; PMIDs: 10764043, 26310628). (SP) 0906 - Segregation evidence for this variant is inconclusive. There is currently insufficient information to determine segregation of this variant with disease (PMIDs: 10764043, 26310628). (I) 1010 - Functional evidence for this variant is inconclusive. Luciferase reporter constructs with the p.(Tyr119Cys) variant transfected into RT4 schwann cells did not demonstrate increased unfolded protein response (UPR) compared to WT constructs (PMID: 29687021). However, mutant constructs with other variants have also been shown to not result in a significantly increased UPR compared to the WT (PMID: 18337304). (I) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

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

Oct 30, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces tyrosine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 119 of the MPZ protein (p.Tyr119Cys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with Charcot-Marie-Tooth disease (PMID: 10764043, 26310628; internal data). It has also been observed to segregate with disease in related individuals. Invitae Evidence Modeling of clinical and family history, age, sex, and reported ancestry of multiple individuals with this MPZ variant has been performed. This variant is expected to be pathogenic with a positive predictive value of at least 99%. This is a validated machine learning model that incorporates the clinical features of 11,906 individuals referred to our laboratory for MPZ testing. ClinVar contains an entry for this variant (Variation ID: 245997). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed for this missense variant. However, the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on MPZ protein function. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on MPZ function (PMID: 29687021). For these reasons, this variant has been classified as Pathogenic. -

Charcot-Marie-Tooth disease Uncertain:1

-

Inherited Neuropathy Consortium

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Inborn genetic diseases Uncertain:1

Dec 11, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.356A>G (p.Y119C) alteration is located in exon 3 (coding exon 3) of the MPZ gene. This alteration results from a A to G substitution at nucleotide position 356, causing the tyrosine (Y) at amino acid position 119 to be replaced by a cysteine (C). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.63
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Uncertain	0.13
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.60	D
Eigen	Uncertain	0.33
Eigen_PC	Uncertain	0.35
FATHMM_MKL	Benign	0.74	D
LIST_S2	Uncertain	0.91	D
M_CAP	Benign	0.040	D
MetaRNN	Uncertain	0.74	D
MetaSVM	Benign	-0.80	T
MutationAssessor	Uncertain	2.0	M
PrimateAI	Uncertain	0.66	T
PROVEAN	Uncertain	-3.1	D
REVEL	Uncertain	0.38
Sift	Uncertain	0.0040	D
Sift4G	Uncertain	0.016	D
Polyphen		0.99	D
Vest4		0.68
MutPred		0.47		Loss of phosphorylation at Y119 (P = 0.0516);
MVP		0.92
MPC		1.3
ClinPred		0.98	D
GERP RS		4.8
Varity_R		0.67
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: rs879254038; hg19: chr1-161276590;