chrX-103776997-T-G

Position:

• chrX-103776997-T-G

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM2 PP5_Very_Strong

The NM_000533.5(PLP1):​c.2T>G​(p.Met1?) variant causes a start lost, splice region change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 23)
• Consequence: PLP1 NM_000533.5 start_lost, splice_region
• Scores: Splicing: ADA: 0.007752
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 4.55

Genes affected

PLP1 (HGNC:9086): (proteolipid protein 1) This gene encodes a transmembrane proteolipid protein that is the predominant component of myelin. The encoded protein may play a role in the compaction, stabilization, and maintenance of myelin sheaths, as well as in oligodendrocyte development and axonal survival. Mutations in this gene cause Pelizaeus-Merzbacher disease and spastic paraplegia type 2. Alternatively splicing results in multiple transcript variants, including the DM20 splice variant. [provided by RefSeq, Feb 2015]

RAB9B (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant X-103776997-T-G is Pathogenic according to our data. Variant chrX-103776997-T-G is described in ClinVar as [Pathogenic]. Clinvar id is 521932.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PLP1	NM_000533.5	c.2T>G	p.Met1?	start_lost, splice_region_variant	1/7	ENST00000621218.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PLP1	ENST00000621218.5	c.2T>G	p.Met1?	start_lost, splice_region_variant	1/7	1	NM_000533.5	P1

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 27

GnomAD4 genome Cov.: 23

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary spastic paraplegia 2 Pathogenic:2

Pathogenic, criteria provided, single submitter	research	Kasturba Medical College, Manipal, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Nov 01, 2023	Variant summary: PLP1 c.2T>G (p.Met1Arg) alters the initiation codon and is predicted to result either in absence of the protein or truncation of the encoded protein due to translation initiation at a downstream codon. An alternative downstream in-frame start codon (Met206) is located in the encoded protein. An activation of potential downstream translation at this initiation site would result in a shortened protein missing the first 205 amino acids from the protein sequence. Three of four in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 180287 control chromosomes (gnomAD). c.2T>G has been reported in the literature in the hemizygous state multiple male individuals affected with Hereditary spastic paraplegia 2 and has been found to segregate with the disease phenotype in an X-linked manner within families (e.g. Hand_2012, Hebbar_2019). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 22343157, 30337681). One submitter has cited a clinical-significance assessment for this variant to ClinVar after 2014 and has classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Inborn genetic diseases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 27, 2017

- -

Pelizaeus-Merzbacher disease Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Molecular Diagnostics Lab, Nemours Children's Health, Delaware

Nov 11, 2021

This missense variant (c.2T>G, p.Met1Arg) has not been observed in population databases (gnomAD). It has been described in the literature (PMID 22343157), and other changes that alter the initiation codon have also been reported (PMID 10417279, 8786077, 12910435). Variant prediction programs suggest a deleterious effect on the PLP1 protein, but no functional studies have been published. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.72	D
BayesDel_noAF	Pathogenic	0.74
CADD	Benign	23
DANN	Uncertain	0.98
DEOGEN2	Benign	0.025	T;T;T;T;T;T;T;T;.
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.90	D;.;D;D;D;D;D;.;D
M_CAP	Pathogenic	0.99	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.96	D
MutationTaster	Benign	1.0	D;D;D
PROVEAN	Benign	-1.9	N;.;N;N;N;.;N;.;.
REVEL	Pathogenic	0.69
Sift	Uncertain	0.0010	D;.;D;D;D;.;D;.;.
Sift4G	Uncertain	0.0030	D;D;D;D;D;D;D;D;D
Polyphen		0.67, 0.044	.;.;.;.;.;P;.;P;B
Vest4		0.95, 0.95, 0.85
MutPred		0.99		Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);
MVP		1.0
ClinPred		0.98	D
GERP RS		5.4
Varity_R		0.98
gMVP		0.87

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.0078
dbscSNV1_RF	Benign	0.070
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: rs864622194; hg19: chrX-103031925;