chrX-150659694-G-A

Variant names:

• chrX-150659694-G-A
• rs886044782
• NM_000252.3:c.1291G>A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PS1_Moderate PM2 PP3_Moderate

The NM_000252.3(MTM1):​c.1291G>A​(p.Asp431Asn) 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). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely pathogenic in UniProt.

• 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:3
• Conservation: PhyloP100: 9.94

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PS1: Transcript NM_000252.3 (MTM1) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in UniProt
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.842

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MTM1	NM_000252.3	c.1291G>A	p.Asp431Asn	missense_variant	Exon 12 of 15	ENST00000370396.7	NP_000243.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MTM1	ENST00000370396.7	c.1291G>A	p.Asp431Asn	missense_variant	Exon 12 of 15	1	NM_000252.3	ENSP00000359423.3

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 23

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1 Uncertain:2

Apr 29, 2015

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The D431N variant in the MTM1 gene has been reported in a male patient affected with X-linked myotubular myopathy whose mother was noted to be a carrier (Laporte et al., 1997). The D431N variant was reported in cis with a second D433N variant, however the two missense variants are nearby and therefore would be considered as an insertion deletion alteration c.1291_1297delGATGCTGinsAATGCTA using alternate nomenclature. The D431N variant was not observed in approximately 6500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. The D431N variant is a semi-conservative amino acid substitution, which may impact secondary protein structure as these residues differ in some properties. This substitution occurs at a position that is conserved across species. In silico analysis is inconsistent in its predictions as to whether or not the variant is damaging to the protein structure/function. A missense variant in a nearby residue (R421Q) has been reported in the Human Gene Mutation Database in association with X-linked recessive myotubular myopathy (Stenson et al., 2014), supporting the functional importance of this region of the protein. The D431N variant is a strong candidate for a disease-causing variant, however the possibility it may be a rare benign variant cannot be excluded -

May 16, 2017

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 23, 2017

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Asp431Asn variant in MTM1 has been reported in 1 male with X-linked recessive myotubular myopathy, who carried a second variant 2 amino acids downstream on the same allele (p.Asp433Asn; Laporte 1997). Please note, it is unclear if these two variants occurred independently or as a single event (p.Asp431_Asp433delinsAsnAlaAsn). Both variants were absent from large population studies. Computational prediction tools and conservation analyses suggest that the p.Asp431Asn variant may impact the protein, though this information is not predictive enough to determine pathogenicity. In summary, the clinical significance of the p.Asp431Asn variant is uncertain. -

not specified Uncertain:1

May 22, 2017

Genetic Services Laboratory, University of Chicago

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.44
BayesDel_addAF	Benign	-0.013	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	23
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.88	D
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.52	D
MetaRNN	Pathogenic	0.84	D
MetaSVM	Uncertain	0.60	D
MutationAssessor	Benign	1.5	L
PrimateAI	Uncertain	0.75	T
PROVEAN	Uncertain	-3.8	D
REVEL	Uncertain	0.48
Sift	Benign	0.036	D
Sift4G	Benign	0.062	T
Polyphen		0.58	P
Vest4		0.82
MutPred		0.25		Loss of ubiquitination at K427 (P = 0.0828);
MVP		0.96
MPC		1.6
ClinPred		0.99	D
GERP RS		5.5
Varity_R		0.56
gMVP		0.80

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.21		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.21		Position offset: -30

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs886044782; hg19: chrX-149828167; COSMIC: COSV100080294;