Genetic Variant MPZ:n.*665_*666delGA (chr1-161304965-TTC-T) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The ENST00000463290.5(MPZ):n.*665_*666delGA variant causes a non coding transcript exon change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00157 in 636 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 26)

Exomes 𝑓: 0.0016 ( 0 hom. )

Consequence

MPZ
ENST00000463290.5 non_coding_transcript_exon

Scores

Not classified

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -0.360

Publications

0 publications found

Variant links:

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]

MPZ Gene-Disease associations (from GenCC):

Charcot-Marie-Tooth disease
Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
Charcot-Marie-Tooth disease type 1B
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Laboratory for Molecular Medicine, Orphanet
neuropathy, congenital hypomyelinating, 2
Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
autosomal dominant intermediate Charcot-Marie-Tooth disease with neuropathic pain
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Charcot-Marie-Tooth disease dominant intermediate D
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Charcot-Marie-Tooth disease type 2I
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Charcot-Marie-Tooth disease type 2J
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Charcot-Marie-Tooth disease type 3
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

MPZ links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	Effect	Exon rank	MANE	Protein	UniProt
MPZ	NM_000530.8 link	c.909_910delGA	3_prime_UTR_variant	Exon 6 of 6	ENST00000533357.5	NP_000521.2	P25189-1
MPZ	NM_001315491.2 link	c.717_718delGA	3_prime_UTR_variant	Exon 6 of 6		NP_001302420.1	P25189A0A5F9ZI26
MPZ	XM_017001321.3 link	c.676-626_676-625delGA	intron_variant	Intron 5 of 5		XP_016856810.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MPZ	ENST00000533357.5 link	c.909_910delGA		3_prime_UTR_variant	Exon 6 of 6	1	NM_000530.8	ENSP00000432943.1		P25189-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00157

AC:

AN:

636

Hom.:

AF XY:

0.00263

AC XY:

AN XY:

380

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

American (AMR)

AC:

AN:

Ashkenazi Jewish (ASJ)

AC:

AN:

East Asian (EAS)

AF:

0.00

AC:

AN:

140

South Asian (SAS)

AF:

0.00

AC:

AN:

European-Finnish (FIN)

AF:

0.00

AC:

AN:

428

Middle Eastern (MID)

AC:

AN:

European-Non Finnish (NFE)

AF:

0.0200

AC:

AN:

Other (OTH)

AF:

0.00

AC:

AN:

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.225

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

-0.36

Mutation Taster

=100/0

polymorphism

(source)

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

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1-161304965-TTCTC-TTC

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over