3-48593101-C-A

Variant names:

• chr3-48593101-C-A
• rs775288140
• NM_000094.4:c.682+1G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PVS1_Moderate PM2 PP5_Moderate

The NM_000094.4(COL7A1):​c.682+1G>T variant causes a splice donor, intron 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 predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: COL7A1 NM_000094.4 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 4.22
• Publications: 0 publications found

Genes affected

COL7A1 (HGNC:2214): (collagen type VII alpha 1 chain) This gene encodes the alpha chain of type VII collagen. The type VII collagen fibril, composed of three identical alpha collagen chains, is restricted to the basement zone beneath stratified squamous epithelia. It functions as an anchoring fibril between the external epithelia and the underlying stroma. Mutations in this gene are associated with all forms of dystrophic epidermolysis bullosa. In the absence of mutations, however, an acquired form of this disease can result from an autoimmune response made to type VII collagen. [provided by RefSeq, Jul 2008]

COL7A1 Gene-Disease associations (from GenCC):

• epidermolysis bullosa with congenital localized absence of skin and deformity of nails

  Inheritance: AD, AR Classification: DEFINITIVE, STRONG Submitted by: PanelApp Australia, G2P, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• dystrophic epidermolysis bullosa pruriginosa

  Inheritance: AR, AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, G2P, Orphanet
• recessive dystrophic epidermolysis bullosa

  Inheritance: AR, AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: PanelApp Australia, Orphanet, Genomics England PanelApp, Ambry Genetics, G2P, ClinGen
• generalized dominant dystrophic epidermolysis bullosa

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), PanelApp Australia, Orphanet
• pretibial dystrophic epidermolysis bullosa

  Inheritance: AD, AR Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp
• transient bullous dermolysis of the newborn

  Inheritance: AD, AR Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp
• acral dystrophic epidermolysis bullosa

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• dystrophic epidermolysis bullosa, nails only

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• recessive dystrophic epidermolysis bullosa inversa

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• recessive dystrophic epidermolysis bullosa-generalized other

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.018336164 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-48593101-C-A is Pathogenic according to our data. Variant chr3-48593101-C-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2627281.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL7A1	NM_000094.4	c.682+1G>T		splice_donor_variant, intron_variant	Intron 6 of 118	ENST00000681320.1	NP_000085.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL7A1	ENST00000681320.1	c.682+1G>T		splice_donor_variant, intron_variant	Intron 6 of 118		NM_000094.4	ENSP00000506558.1
COL7A1	ENST00000328333.12	c.682+1G>T		splice_donor_variant, intron_variant	Intron 5 of 117	1		ENSP00000332371.8

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

COL7A1-related disorder Pathogenic:1

Sep 20, 2023

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

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: COL7A1 c.682+1G>T 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: Four predict the variant abolishes a canonical 5' splicing donor site. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 251360 control chromosomes (gnomAD). c.682+1G>T has been reported in the literature in an individual affected with Dystrophic Epidermolysis Bullosa, Recessive who was compound heterozygous with a truncating variant (Chen_2023). These data suggest the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 36287101). No submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.27
CADD	Pathogenic	29
DANN	Uncertain	0.99
Eigen	Pathogenic	0.76
Eigen_PC	Uncertain	0.52
FATHMM_MKL	Benign	0.74	D
PhyloP100		4.2
GERP RS		4.2
Mutation Taster		=0/100	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.93		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.93		Position offset: 1

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

Other links and lift over

dbSNP: rs775288140; hg19: chr3-48630534;