chrX-33020156-T-G

Position:

• chrX-33020156-T-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_004006.3(DMD):​c.76A>C​(p.Asn26His) variant causes a missense change. 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N26D) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 23)
• Consequence: DMD NM_004006.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.94

Genes affected

DMD (HGNC:2928): (dystrophin) This gene spans a genomic range of greater than 2 Mb and encodes a large protein containing an N-terminal actin-binding domain and multiple spectrin repeats. The encoded protein forms a component of the dystrophin-glycoprotein complex (DGC), which bridges the inner cytoskeleton and the extracellular matrix. Deletions, duplications, and point mutations at this gene locus may cause Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), or cardiomyopathy. Alternative promoter usage and alternative splicing result in numerous distinct transcript variants and protein isoforms for this gene. [provided by RefSeq, Dec 2016]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.981

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
DMD	NM_004006.3	c.76A>C	p.Asn26His	missense_variant	2/79	ENST00000357033.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
DMD	ENST00000357033.9	c.76A>C	p.Asn26His	missense_variant	2/79	1	NM_004006.3	P4

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 25

GnomAD4 genome Cov.: 23

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Duchenne muscular dystrophy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 01, 2018

This sequence change replaces asparagine with histidine at codon 26 of the DMD protein (p.Asn26His). The asparagine residue is highly conserved and there is a small physicochemical difference between asparagine and histidine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with DMD-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C65"). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.69
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.31
CADD	Pathogenic	26
DANN	Uncertain	0.98
DEOGEN2	Pathogenic	0.90	.;D;.;.;.;.;D
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.99	D;.;D;D;T;T;D
M_CAP	Pathogenic	0.61	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	0.99	D;D;D
PrimateAI	Uncertain	0.62	T
PROVEAN	Uncertain	-3.5	.;D;.;D;N;D;D
REVEL	Pathogenic	0.87
Sift	Uncertain	0.0020	.;D;.;D;D;D;D
Sift4G	Uncertain	0.0020	D;D;D;D;D;D;D
Polyphen		1.0, 0.92	.;D;.;.;.;.;P
Vest4		0.88
MutPred		0.90		.;.;Loss of MoRF binding (P = 0.1102);Loss of MoRF binding (P = 0.1102);Loss of MoRF binding (P = 0.1102);Loss of MoRF binding (P = 0.1102);.;
MVP		0.99
MPC		0.024
ClinPred		0.99	D
GERP RS		5.2
gMVP		0.89

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: rs1057521321; hg19: chrX-33038273;