17-15239555-A-T

Variant names:

• chr17-15239555-A-T
• rs863225027
• NM_000304.4:c.235T>A

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PM5 PP3_Moderate PP5_Very_Strong

The NM_000304.4(PMP22):​c.235T>A​(p.Ser79Thr) 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S79C) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: PMP22 NM_000304.4 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 2.83

Genes affected

PMP22 (HGNC:9118): (peripheral myelin protein 22) This gene encodes an integral membrane protein that is a major component of myelin in the peripheral nervous system. Studies suggest two alternately used promoters drive tissue-specific expression. Various mutations of this gene are causes of Charcot-Marie-Tooth disease Type IA, Dejerine-Sottas syndrome, and hereditary neuropathy with liability to pressure palsies. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2013]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a transmembrane_region Helical (size 26) in uniprot entity PMP22_HUMAN there are 19 pathogenic changes around while only 0 benign (100%) in NM_000304.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-15239554-G-C is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.873
• PP5: Variant 17-15239555-A-T is Pathogenic according to our data. Variant chr17-15239555-A-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 217236.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr17-15239555-A-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PMP22	NM_000304.4	c.235T>A	p.Ser79Thr	missense_variant	Exon 4 of 5	ENST00000312280.9	NP_000295.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PMP22	ENST00000312280.9	c.235T>A	p.Ser79Thr	missense_variant	Exon 4 of 5	1	NM_000304.4	ENSP00000308937.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Charcot-Marie-Tooth disease, type IA Pathogenic:1

Aug 14, 2015

Athena Diagnostics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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

Jun 23, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces serine with threonine at codon 79 of the PMP22 protein (p.Ser79Thr). The serine residue is highly conserved and there is a small physicochemical difference between serine and threonine. This variant is not present in population databases (ExAC no frequency). This variant has been observed to be de novo in an individual affected with Dejerine–Sottas neuropathy (PMID: 22006697). ClinVar contains an entry for this variant (Variation ID: 217236). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant disrupts the p.Ser79 amino acid residue in PMP22. Other variants that disrupt this residue have been observed in individuals with PMP22-related conditions (PMID: 8510709, 9452053), which suggests that this may be a clinically significant amino acid residue. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.87
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Benign	23
DANN	Benign	0.90
DEOGEN2	Pathogenic	0.84	D;D;D;D;D;.;.;D;.
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.30
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.84	T;.;.;.;.;D;D;D;D
M_CAP	Pathogenic	0.57	D
MetaRNN	Pathogenic	0.87	D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.45	D
MutationAssessor	Pathogenic	3.1	M;M;M;.;.;.;.;.;.
PrimateAI	Uncertain	0.70	T
PROVEAN	Benign	-2.3	.;N;N;.;N;.;.;.;N
REVEL	Pathogenic	0.78
Sift	Uncertain	0.018	.;D;D;.;D;.;.;.;D
Sift4G	Uncertain	0.011	D;D;D;.;D;.;.;.;D
Polyphen		0.82	P;P;P;.;.;.;.;.;.
Vest4		0.65
MutPred		0.79		Loss of helix (P = 0.3949);Loss of helix (P = 0.3949);Loss of helix (P = 0.3949);Loss of helix (P = 0.3949);Loss of helix (P = 0.3949);.;.;Loss of helix (P = 0.3949);Loss of helix (P = 0.3949);
MVP		0.99
MPC		1.1
ClinPred		0.94	D
GERP RS		4.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.17
gMVP		0.92

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: rs863225027; hg19: chr17-15142872;