1-161305851-G-A

Variant names:

• chr1-161305851-G-A
• rs776448650
• NM_000530.8:c.*25C>T

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_001315491.2(MPZ):​c.772C>T​(p.Arg258Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000733 in 545,670 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 5/5 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R258G) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000073 (0 hom.)
• Consequence: MPZ NM_001315491.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.68

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 Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.67).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MPZ	NM_000530.8	c.*25C>T		3_prime_UTR_variant	Exon 6 of 6	ENST00000533357.5	NP_000521.2
MPZ	NM_001315491.2	c.772C>T	p.Arg258Trp	missense_variant	Exon 6 of 6		NP_001302420.1
MPZ	XM_017001321.3	c.675+257C>T		intron_variant	Intron 5 of 5		XP_016856810.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MPZ	ENST00000533357	c.*25C>T		3_prime_UTR_variant	Exon 6 of 6	1	NM_000530.8	ENSP00000432943.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000416 AC: 1 AN: 240192 Hom.: 0 AF XY: 0.00000770 AC XY: 1 AN XY: 129926

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000344

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000733 AC: 4 AN: 545670 Hom.: 0 Cov.: 16 AF XY: 0.00000341 AC XY: 1 AN XY: 293272

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000146

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000593

Gnomad4 OTH exome AF: 0.0000436

GnomAD4 genome Cov.: 31

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.67
CADD	Benign	20
DANN	Benign	0.81

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs776448650; hg19: chr1-161275641;