X-150660384-T-C

Variant names:

• chrX-150660384-T-C
• rs587783783
• NM_000252.3:c.1367T>C

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PP3_Strong PP5

The NM_000252.3(MTM1):​c.1367T>C​(p.Phe456Ser) variant causes a missense change involving the alteration of a 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 Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 23)
• Consequence: MTM1 NM_000252.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 7.64
• Publications: 0 publications found

Genes affected

MTM1 (HGNC:7448): (myotubularin 1) This gene encodes a dual-specificity phosphatase that acts on both phosphotyrosine and phosphoserine. It is required for muscle cell differentiation and mutations in this gene have been identified as being responsible for X-linked myotubular myopathy. [provided by RefSeq, Jul 2008]

MTM1 Gene-Disease associations (from GenCC):

• X-linked myotubular myopathy

  Inheritance: XL Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: G2P, Ambry Genetics, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), ClinGen, Myriad Women’s Health, Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 2 uncertain in NM_000252.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.99
• PP5: Variant X-150660384-T-C is Pathogenic according to our data. Variant chrX-150660384-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 158925.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MTM1	NM_000252.3	c.1367T>C	p.Phe456Ser	missense_variant	Exon 13 of 15	ENST00000370396.7	NP_000243.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MTM1	ENST00000370396.7	c.1367T>C	p.Phe456Ser	missense_variant	Exon 13 of 15	1	NM_000252.3	ENSP00000359423.3

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 26

GnomAD4 genome Cov.: 23

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Severe X-linked myotubular myopathy Pathogenic:1 Uncertain:1

Mar 05, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, this variant is a rare missense change with uncertain impact on protein function. There is no indication that it causes disease, but the available evidence is currently insufficient to prove that conclusively. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with an MTM1-related disease. ClinVar contains an entry for this variant (Variation ID: 158925). This sequence change replaces phenylalanine with serine at codon 456 of the MTM1 protein (p.Phe456Ser). The phenylalanine residue is highly conserved and there is a large physicochemical difference between phenylalanine and serine. -

Feb 08, 2013

Genetic Services Laboratory, University of Chicago

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.73	D
BayesDel_noAF	Pathogenic	0.81
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.93	D
M_CAP	Pathogenic	0.99	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.2	H
PhyloP100		7.6
PrimateAI	Uncertain	0.70	T
PROVEAN	Pathogenic	-7.3	D
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.98
MutPred		0.85		Gain of disorder (P = 0.0032);
MVP		1.0
MPC		2.2
ClinPred		1.0	D
GERP RS		5.6
Varity_R		0.99
gMVP		0.99
Mutation Taster		=0/100	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs587783783; hg19: chrX-149828857;