rs121912832

Positions:

• chr3-48575512-C-T

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_000094.4(COL7A1):​c.6007G>A​(p.Gly2003Arg) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,460,452 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G2003E) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: COL7A1 NM_000094.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 6.10

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]

ACMG classification

Verdict is Pathogenic. Variant got 19 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 6 uncertain in NM_000094.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-48575511-C-T is described in Lovd as [Pathogenic].
• PP2: Missense variant where missense usually causes diseases, COL7A1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.993
• PP5: Variant 3-48575512-C-T is Pathogenic according to our data. Variant chr3-48575512-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 17430.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr3-48575512-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL7A1	NM_000094.4	c.6007G>A	p.Gly2003Arg	missense_variant	74/119	ENST00000681320.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL7A1	ENST00000681320.1	c.6007G>A	p.Gly2003Arg	missense_variant	74/119		NM_000094.4	P1
COL7A1	ENST00000328333.12	c.6007G>A	p.Gly2003Arg	missense_variant	73/118	1		P1
COL7A1	ENST00000487017.5	n.1924G>A		non_coding_transcript_exon_variant	39/83	5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1460452 Hom.: 0 Cov.: 39 AF XY: 0.00000138 AC XY: 1 AN XY: 726556

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	May 25, 2022	For these reasons, this variant has been classified as Pathogenic. This variant disrupts the triple helix domain of COL7A1. Glycine residues within the Gly-Xaa-Yaa repeats of the triple helix domain are required for the structure and stability of fibrillar collagens (PMID: 7695699, 8218237, 19344236), and variants at these glycine residues in COL7A1 are more frequently observed in individuals with disease than in the general population (PMID: 22058051). However, the clinical significance of this observation remains uncertain since only a limited number of affected individuals have been described to date. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt COL7A1 protein function. ClinVar contains an entry for this variant (Variation ID: 17430). This missense change has been observed in individuals with autosomal dominant dystrophic epidermolysis bullosa (PMID: 8752681, 29963685). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 2003 of the COL7A1 protein (p.Gly2003Arg). -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Sep 06, 2022	Located in the highly conserved Gly-X-Y repeat of the collagenous domain; Glycine substitution variants in this region of the COLVII protein destabilize the collagen triple helix resulting in skin fragility due to poor anchoring of the basement membrane to the underlying dermis (Pfendner and Lucky, 2018); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 29722429, 21448560, 26707537, 8752681, 29963685, 20598510, 19681861, 8618021, 30523708, 34338359) -

Epidermolysis bullosa dystrophica Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Natera, Inc.

Sep 16, 2020

- -

Dominant dystrophic epidermolysis bullosa with absence of skin Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Apr 01, 1996

- -

Inborn genetic diseases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 01, 2015

- -

COL7A1-related disorder Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Dec 15, 2023

The COL7A1 c.6007G>A variant is predicted to result in the amino acid substitution p.Gly2003Arg. This variant has been reported in several individuals with autosomal dominant or autosomal recessive epidermolysis bullosa dystrophica (see for example, Christiano et al. 1996. PubMed ID: 8752681; Yenamandra et al. 2018. PubMed ID: 29963685; Sawka and Funk. 2021. PubMed ID: 34338359). This variant has not been reported in a large population database, indicating this variant is rare. The amino acid p.Gly2003Arg resides in exon 73 and is within the triple helical domain of the COL7A1 protein (amino acids 1254-2783); and, glycine substitution variants in the triple helical domain (Gly-X-Y; especially in exons 73, 74, and 75) are predominant in autosomal dominant dystrophic epidermolysis bullosa (DDEB; Pfendner and Lucky. 2018. PubMed ID: 20301481). This variant is interpreted as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.90
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	28
DANN	Benign	0.96
DEOGEN2	Pathogenic	0.84	D
Eigen	Pathogenic	0.85
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.52	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.99	D
MutationAssessor	Pathogenic	4.7	H
MutationTaster	Benign	1.0	A;A
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-6.1	D
REVEL	Pathogenic	0.96
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.95
MutPred		0.93		Loss of glycosylation at K2005 (P = 0.0028);
MVP		0.97
MPC		0.30
ClinPred		1.0	D
GERP RS		5.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.55
gMVP		1.0

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: rs121912832; hg19: chr3-48612945;