rs68132885

Positions:

• chr7-94410532-G-A
• chr7-94410532-G-C

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM2 PP3_Strong PP5_Very_Strong

The NM_000089.4(COL1A2):​c.1197+5G>A variant causes a splice donor 5th base, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL1A2 NM_000089.4 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 6.92

Genes affected

COL1A2 (HGNC:2198): (collagen type I alpha 2 chain) This gene encodes the pro-alpha2 chain of type I collagen whose triple helix comprises two alpha1 chains and one alpha2 chain. Type I is a fibril-forming collagen found in most connective tissues and is abundant in bone, cornea, dermis and tendon. Mutations in this gene are associated with osteogenesis imperfecta types I-IV, Ehlers-Danlos syndrome type VIIB, recessive Ehlers-Danlos syndrome Classical type, idiopathic osteoporosis, and atypical Marfan syndrome. Symptoms associated with mutations in this gene, however, tend to be less severe than mutations in the gene for the alpha1 chain of type I collagen (COL1A1) reflecting the different role of alpha2 chains in matrix integrity. Three transcripts, resulting from the use of alternate polyadenylation signals, have been identified for this gene. [provided by R. Dalgleish, Feb 2008]

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. Scorers claiming Uncertain: max_spliceai. No scorers claiming Benign.
• PP5: Variant 7-94410532-G-A is Pathogenic according to our data. Variant chr7-94410532-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 425646.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr7-94410532-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL1A2	NM_000089.4	c.1197+5G>A		splice_donor_5th_base_variant, intron_variant		ENST00000297268.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL1A2	ENST00000297268.11	c.1197+5G>A		splice_donor_5th_base_variant, intron_variant		1	NM_000089.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Osteogenesis imperfecta with normal sclerae, dominant form Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jan 01, 1996

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not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

May 22, 2019

Published functional studies demonstrate that the c.1197+5 G>A results in skipping of exon 21 encoding Gly-X-Y repeats and the resulting protein showed intracellular retention (Nicholls et al., 1996); Not observed in large population cohorts (Lek et al., 2016); This variant is associated with the following publications: (PMID: 25525159, 26177859, 17078022, 8829655, 28498836, 25944380, 27510842, 30715774, 31414283) -

Osteogenesis imperfecta type I;C0268335:Ehlers-Danlos syndrome, classic type, 1 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 10, 2023

This sequence change falls in intron 21 of the COL1A2 gene. It does not directly change the encoded amino acid sequence of the COL1A2 protein. RNA analysis indicates that this variant induces altered splicing and likely results in a shortened protein product. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with autosomal dominant osteogenesis imperfecta (PMID: 17078022, 30715774). This variant is also known as g.17903G>A, IVS21+5G>A. ClinVar contains an entry for this variant (Variation ID: 425646). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant results in skipping of exon 21, but is expected to preserve the integrity of the reading-frame (PMID: 17078022). This variant disrupts the triple helix domain of COL1A2. 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). In COL1A2, variants affecting these glycine residues are significantly enriched in individuals with disease (PMID: 9016532, 17078022) compared to the general population (ExAC). For these reasons, this variant has been classified as Pathogenic. -

Osteogenesis imperfecta type I Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Department of Medical Sciences, Uppsala University

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.24
CADD	Benign	21
DANN	Benign	0.97

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
SpliceAI score (max)		0.38		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.38		Position offset: -5

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

Publications

LitVar

Other links and lift over

dbSNP: rs68132885; hg19: chr7-94039844;