X-32472311-T-G

Variant names:

• chrX-32472311-T-G
• rs794727357
• NM_004006.3:c.2804-2A>C

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_004006.3(DMD):​c.2804-2A>C variant causes a splice acceptor, intron 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. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 23)
• Consequence: DMD NM_004006.3 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.44

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 Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 4.3, offset of 32, new splice context is: tgccaccaatgcgctatcAGgag. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant X-32472311-T-G is Pathogenic according to our data. Variant chrX-32472311-T-G is described in ClinVar as [Pathogenic]. Clinvar id is 217190.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chrX-32472311-T-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DMD	NM_004006.3	c.2804-2A>C		splice_acceptor_variant, intron_variant	Intron 21 of 78	ENST00000357033.9	NP_003997.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DMD	ENST00000357033.9	c.2804-2A>C		splice_acceptor_variant, intron_variant	Intron 21 of 78	1	NM_004006.3	ENSP00000354923.3

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 23

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Duchenne muscular dystrophy Pathogenic:2

Jan 14, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 21 of the DMD gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. This variant is not present in population databases (ExAC no frequency). This variant has been observed to be hemizygous in individuals affected with Duchenne or Becker muscular dystrophy (PMID: 15351422, 27593222). ClinVar contains an entry for this variant (Variation ID: 217190). Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in DMD are known to be pathogenic (PMID: 16770791, 25007885). For these reasons, this variant has been classified as Pathogenic. -

Oct 21, 2013

Athena Diagnostics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Qualitative or quantitative defects of dystrophin Pathogenic:1

Mar 01, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: DMD c.2804-2A>C is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Three predict the variant abolishes a 3 acceptor site. At least one publication reports experimental evidence that this variant affects mRNA splicing (Deburgrave_2007). The variant was absent in 182614 control chromosomes (gnomAD). c.2804-2A>C has been reported in the literature in individuals affected with Duchenne Muscular Dystrophy (Tuffery-Giraud_2004, Deburgrave_2007, Cho_2017). These data indicate that the variant may be associated with disease. Two ClinVar submitters (evaluation after 2014) cite the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

not provided Pathogenic:1

Feb 23, 2021

Revvity Omics, Revvity

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.17	D
BayesDel_noAF	Uncertain	0.0
CADD	Pathogenic	31
DANN	Uncertain	0.99
FATHMM_MKL	Uncertain	0.96	D
GERP RS		5.0

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.78		Position offset: -34
DS_AL_spliceai		0.97		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs794727357; hg19: chrX-32490428;