rs121912828

Positions:

• chr3-48566281-A-T

Variant summary

Our verdict is Pathogenic. Variant got 15 ACMG points: 15P and 0B. PM1 PM2 PP2 PP3_Moderate PP5_Very_Strong

The NM_000094.4(COL7A1):​c.8393T>A​(p.Met2798Lys) variant causes a missense change. The variant allele was found at a frequency of 0.00000658 in 152,074 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 Likely pathogenic (★★).

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: COL7A1 NM_000094.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 6.25

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 15 ACMG points.

• PM1: In a region_of_interest Nonhelical region (NC2) (size 159) in uniprot entity CO7A1_HUMAN there are 6 pathogenic changes around while only 2 benign (75%) in NM_000094.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), COL7A1. . Gene score misZ 1.5899 (greater than the threshold 3.09). Trascript score misZ 4.0428 (greater than threshold 3.09). GenCC has associacion of gene with recessive dystrophic epidermolysis bullosa, dystrophic epidermolysis bullosa pruriginosa, recessive dystrophic epidermolysis bullosa-generalized other, transient bullous dermolysis of the newborn, epidermolysis bullosa with congenital localized absence of skin and deformity of nails, generalized dominant dystrophic epidermolysis bullosa, dystrophic epidermolysis bullosa, nails only, acral dystrophic epidermolysis bullosa, recessive dystrophic epidermolysis bullosa inversa, pretibial dystrophic epidermolysis bullosa.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.899
• PP5: Variant 3-48566281-A-T is Pathogenic according to our data. Variant chr3-48566281-A-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 17423.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr3-48566281-A-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
COL7A1	NM_000094.4	c.8393T>A	p.Met2798Lys	missense_variant	114/119	ENST00000681320.1	NP_000085.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
COL7A1	ENST00000681320.1	c.8393T>A	p.Met2798Lys	missense_variant	114/119		NM_000094.4	ENSP00000506558	P1
COL7A1	ENST00000328333.12	c.8393T>A	p.Met2798Lys	missense_variant	113/118	1		ENSP00000332371	P1
COL7A1	ENST00000487017.5	n.5032T>A		non_coding_transcript_exon_variant	78/83	5

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152074 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000242

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 33

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 152074 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74290

Gnomad4 AFR AF: 0.0000242

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000756

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Recessive dystrophic epidermolysis bullosa Pathogenic:2

Pathogenic, no assertion criteria provided	literature only	OMIM	May 01, 1993	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Apr 03, 2024	Variant summary: COL7A1 c.8393T>A (p.Met2798Lys) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 230376 control chromosomes. c.8393T>A has been reported in the literature in individuals affected with Dystrophic Epidermolysis Bullosa, Recessive (Christiano_1993). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication have been ascertained in the context of this evaluation (PMID: 8513326). ClinVar contains an entry for this variant (Variation ID: 17423). Based on the evidence outlined above, the variant was classified as likely pathogenic. -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 17, 2023

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces methionine, which is neutral and non-polar, with lysine, which is basic and polar, at codon 2798 of the COL7A1 protein (p.Met2798Lys). This missense change has been observed in individual(s) with autosomal recessive dystrophic epidermolysis bullosa (PMID: 8513326). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 17423). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on COL7A1 protein function. This variant disrupts the p.Met2798 amino acid residue in COL7A1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 34435747). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.87
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Uncertain	25
DANN	Benign	0.95
DEOGEN2	Benign	0.31	T
Eigen	Uncertain	0.36
Eigen_PC	Uncertain	0.40
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.75	T
M_CAP	Uncertain	0.22	D
MetaRNN	Pathogenic	0.90	D
MetaSVM	Uncertain	-0.11	T
MutationAssessor	Uncertain	2.3	M
MutationTaster	Benign	1.0	A;A
PrimateAI	Uncertain	0.77	T
PROVEAN	Benign	-1.6	N
REVEL	Pathogenic	0.77
Sift	Benign	0.11	T
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.95
MutPred		0.73		Gain of ubiquitination at M2798 (P = 0.017);
MVP		0.91
MPC		0.86
ClinPred		0.97	D
GERP RS		5.1
Varity_R		0.49
gMVP		0.80

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs121912828; hg19: chr3-48603714;