NM_000530.8:c.332C>T

Variant names:

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

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_000530.8(MPZ):​c.332C>T​(p.Ser111Phe) 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S111C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 29)
• Consequence: MPZ NM_000530.8 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• 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 11 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-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.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.985
• PP5: Variant 1-161306824-G-A is Pathogenic according to our data. 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}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MPZ	NM_000530.8	c.332C>T	p.Ser111Phe	missense_variant	Exon 3 of 6	ENST00000533357.5	NP_000521.2
MPZ	NM_001315491.2	c.332C>T	p.Ser111Phe	missense_variant	Exon 3 of 6		NP_001302420.1
MPZ	XM_017001321.3	c.362C>T	p.Ser121Phe	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>T	p.Ser111Phe	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: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Charcot-Marie-Tooth disease Uncertain:2

-

Inherited Neuropathy Consortium

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: literature only

- -

-

Molecular Genetics Laboratory, London Health Sciences Centre

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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

Feb 28, 2024

Human Genetics Section, Sidra Medicine

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

Non-truncating non-synonymous variant is located in a mutational hot spot and/or critical and well-established functional domain. Extremely low frequency in gnomAD population databases. This sequence change replaces serine, which is neutral and polar, with phenylalanine, which is neutral and nonpolar, at codon 111 of the MPZ protein (p.Ser111Phe). Currently available evidence indicates that the variant is likely pathogenic, but additional data are needed to prove that conclusively. -

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	1.0
DEOGEN2	Pathogenic	0.82	D
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Benign	0.85	T
M_CAP	Uncertain	0.15	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Uncertain	0.20	D
MutationAssessor	Pathogenic	3.6	H
PrimateAI	Uncertain	0.61	T
PROVEAN	Pathogenic	-5.7	D
REVEL	Pathogenic	0.67
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.99
MutPred		0.91		Loss of ubiquitination at K108 (P = 0.0787);
MVP		0.92
MPC		1.6
ClinPred		1.0	D
GERP RS		4.7
Varity_R		0.98
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: rs1553259663; hg19: chr1-161276614;