rs1553259785

chr1-161307332-A-Cchr1-161307332-A-G

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_000530.8(MPZ):c.160T>G(p.Ser54Ala) variant causes a missense change involving the alteration of a 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S54C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MPZ NM_000530.8 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.19

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 10 ACMG points.

• PM1: In a hotspot region, there are 11 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 chr1-161307331-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 637324.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Likely_pathogenic=1}.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.963

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MPZ	NM_000530.8	c.160T>G	p.Ser54Ala	missense_variant	2/6	ENST00000533357.5
MPZ	NM_001315491.2	c.160T>G	p.Ser54Ala	missense_variant	2/6
MPZ	XM_017001321.3	c.190T>G	p.Ser64Ala	missense_variant	2/6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MPZ	ENST00000533357.5	c.160T>G	p.Ser54Ala	missense_variant	2/6	1	NM_000530.8	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jun 05, 2019

This sequence change replaces serine with alanine at codon 54 of the MPZ protein (p.Ser54Ala). The serine residue is highly conserved and there is a moderate physicochemical difference between serine and alanine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with MPZ-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. Different missense substitutions at this codon (p.Ser54Cys, p.Ser54Pro) has been reported in affected individuals, but the clinical significance of these variants is uncertain (PMID: 10093067, 25025039, 10533074). 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.89
BayesDel_addAF	Pathogenic	0.30	D
BayesDel_noAF	Pathogenic	0.19
Cadd	Pathogenic	29
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.65	D
Eigen	Pathogenic	0.79
Eigen_PC	Pathogenic	0.75
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Benign	0.62	T
M_CAP	Pathogenic	0.40	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.1	M
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.67	T
PROVEAN	Uncertain	-2.8	D
REVEL	Pathogenic	0.68
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		0.96	D
Vest4		0.72
MutPred		0.86		Loss of disorder (P = 0.2382);
MVP		0.94
MPC		1.3
ClinPred		0.99	D
GERP RS		5.3
Varity_R		0.93
gMVP		0.90

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: rs1553259785; hg19: chr1-161277122;