1-161306824-G-C

Variant names:

• chr1-161306824-G-C
• rs1553259663
• NM_000530.8:c.332C>G

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000530.8(MPZ):​c.332C>G​(p.Ser111Cys) variant causes a missense change. 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. S111F) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 29)
• Consequence: MPZ NM_000530.8 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2 U:1
• Conservation: PhyloP100: 7.13

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.

• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 14 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 chr1-161306824-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 637801.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.982
• PP5: Variant 1-161306824-G-C is Pathogenic according to our data. Variant chr1-161306824-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 449538.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-161306824-G-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MPZ	NM_000530.8	c.332C>G	p.Ser111Cys	missense_variant	Exon 3 of 6	ENST00000533357.5	NP_000521.2
MPZ	NM_001315491.2	c.332C>G	p.Ser111Cys	missense_variant	Exon 3 of 6		NP_001302420.1
MPZ	XM_017001321.3	c.362C>G	p.Ser121Cys	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.332C>G	p.Ser111Cys	missense_variant	Exon 3 of 6	1	NM_000530.8	ENSP00000432943.1

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 29

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Aug 10, 2017

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

A variant that is likely pathogenic has been identified in the MPZ gene. The S111C variant has been previously reported in several individuals with a clinical diagnosis of CMT (Mandich et al., 2009, Manganelli et al., 2014, Sanmaneechai et al., 2015). The S111C variant is not observed in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). The S111C variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs at a position that is conserved across species, and in silico analysis predicts this variant is probably damaging to the protein structure/function. Additionally, missense variants at the same (S111P) and in nearby residues (D109N/E, G110D, I112T) have been reported in Human Gene Mutation Database in association with MPZ-related neuropathies (Stenson et al., 2014), supporting the functional importance of this region of the protein. Therefore, this variant is likely pathogenic; however, the possibility that it is benign cannot be excluded. -

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

Jan 20, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces serine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 111 of the MPZ protein (p.Ser111Cys). 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: 19293842; internal data). ClinVar contains an entry for this variant (Variation ID: 449538). 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) indicates that this missense variant is expected to disrupt MPZ protein function with a positive predictive value of 80%. Experimental studies have shown that this missense change affects MPZ function (PMID: 29687021). This variant disrupts the p.Ser111 amino acid residue in MPZ. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 22176150). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Charcot-Marie-Tooth disease Uncertain:1

-

Inherited Neuropathy Consortium

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.33
CADD	Pathogenic	33
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.81	D
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.78	T
M_CAP	Uncertain	0.12	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Uncertain	0.20	D
MutationAssessor	Pathogenic	3.6	H
PrimateAI	Uncertain	0.59	T
PROVEAN	Pathogenic	-4.7	D
REVEL	Uncertain	0.62
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.90
MutPred		0.91		Loss of ubiquitination at K108 (P = 0.0578);
MVP		0.90
MPC		1.5
ClinPred		1.0	D
GERP RS		4.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.96
gMVP		0.99

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: rs1553259663; hg19: chr1-161276614;