rs777378929

Positions:

• chr1-161306846-C-A
• chr1-161306846-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000530.8(MPZ):​c.310G>T​(p.Asp104Tyr) variant causes a missense change involving the alteration of a non-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 (★).

• Frequency: Genomes: not found (cov: 29)
• Consequence: MPZ NM_000530.8 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.85

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 disulfide_bond (size 77) in uniprot entity MYP0_HUMAN there are 81 pathogenic changes around while only 1 benign (99%) in NM_000530.8
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.785

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MPZ	NM_000530.8	c.310G>T	p.Asp104Tyr	missense_variant	3/6	ENST00000533357.5	NP_000521.2
MPZ	NM_001315491.2	c.310G>T	p.Asp104Tyr	missense_variant	3/6		NP_001302420.1
MPZ	XM_017001321.3	c.340G>T	p.Asp114Tyr	missense_variant	3/6		XP_016856810.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MPZ	ENST00000533357.5	c.310G>T	p.Asp104Tyr	missense_variant	3/6	1	NM_000530.8	ENSP00000432943	P1

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 29

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

Labcorp Genetics (formerly Invitae), Labcorp

May 22, 2015

Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C65"). This variant has not been published in the literature and is not present in population databases. In summary, this is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. This sequence change replaces aspartic acid with tyrosine at codon 104 of the MPZ protein (p.Asp104Tyr). The aspartic acid residue is highly conserved and there is a large physicochemical difference between aspartic acid and tyrosine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.40
BayesDel_addAF	Uncertain	0.10	D
BayesDel_noAF	Benign	-0.090
CADD	Benign	23
DANN	Benign	0.91
DEOGEN2	Uncertain	0.64	D
Eigen	Benign	-0.39
Eigen_PC	Benign	-0.23
FATHMM_MKL	Benign	0.69	D
LIST_S2	Benign	0.76	T
M_CAP	Benign	0.024	T
MetaRNN	Pathogenic	0.78	D
MetaSVM	Benign	-0.97	T
MutationAssessor	Benign	1.2	L
MutationTaster	Benign	0.97	D;D;D;D
PrimateAI	Uncertain	0.48	T
PROVEAN	Pathogenic	-5.5	D
REVEL	Uncertain	0.39
Sift	Benign	0.052	T
Sift4G	Benign	0.19	T
Polyphen		0.0050	B
Vest4		0.68
MutPred		0.70		Loss of ubiquitination at K108 (P = 0.0578);
MVP		0.96
MPC		0.68
ClinPred		0.59	D
GERP RS		3.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.77
gMVP		0.98

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs777378929; hg19: chr1-161276636;