NM_000088.4:c.1821+1G>A

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1_ModeratePM2PP5_Very_Strong

The NM_000088.4(COL1A1):c.1821+1G>A 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 Pathogenic (★★).

Frequency

Genomes: not found (cov: 32)

Consequence

COL1A1
NM_000088.4 splice_donor, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:13

Conservation

PhyloP100: 4.54

Publications

10 publications found

Variant links:

Genes affected

COL1A1 (HGNC:2197): (collagen type I alpha 1 chain) This gene encodes the pro-alpha1 chains 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 VIIA, Ehlers-Danlos syndrome Classical type, Caffey Disease and idiopathic osteoporosis. Reciprocal translocations between chromosomes 17 and 22, where this gene and the gene for platelet-derived growth factor beta are located, are associated with a particular type of skin tumor called dermatofibrosarcoma protuberans, resulting from unregulated expression of the growth factor. Two transcripts, resulting from the use of alternate polyadenylation signals, have been identified for this gene. [provided by R. Dalgleish, Feb 2008]

COL1A1 Gene-Disease associations (from GenCC):

Caffey disease
Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Ambry Genetics, Orphanet, Labcorp Genetics (formerly Invitae), G2P, ClinGen
combined osteogenesis imperfecta and Ehlers-Danlos syndrome 1
Inheritance: AD Classification: DEFINITIVE, MODERATE Submitted by: Ambry Genetics, ClinGen
Ehlers-Danlos syndrome
Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
Ehlers-Danlos syndrome, arthrochalasia type
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, PanelApp Australia, G2P, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), ClinGen
osteogenesis imperfecta type 1
Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
osteogenesis imperfecta type 2
Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
osteogenesis imperfecta type 3
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, Labcorp Genetics (formerly Invitae), Orphanet
osteogenesis imperfecta type 4
Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, Orphanet, ClinGen
Ehlers-Danlos syndrome, classic type, 1
Inheritance: AD Classification: MODERATE Submitted by: ClinGen
Ehlers-Danlos syndrome, classic type
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Ehlers-Danlos/osteogenesis imperfecta syndrome
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
high bone mass osteogenesis imperfecta
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

COL1A1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 12 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.012286689 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 17-50192993-C-T is Pathogenic according to our data. Variant chr17-50192993-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 425580.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000088.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL1A1	NM_000088.4	MANE Select	c.1821+1G>A		splice_donor intron	N/A	NP_000079.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL1A1	ENST00000225964.10	TSL:1 MANE Select	c.1821+1G>A		splice_donor intron	N/A	ENSP00000225964.6
	COL1A1	ENST00000476387.1	TSL:2	n.170+1G>A		splice_donor intron	N/A

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

Cov.:

GnomAD4 genome

Cov.:

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:13

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Osteogenesis imperfecta type I

Pathogenic:5

Department of Medical Sciences, Uppsala University

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

May 23, 2025

Clinical Biomedical Laboratory, Shriners Hospital For Children - Canada

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant affects a canonical splice donor site in intron 26 of COL1A1, a gene for which loss-of-function is a known mechanism of disease. Functional studies provide supporting evidence of the variant having a damaging effect (PMID: 8408653). In the Genome Aggregation Database (gnomAD v2.1.1) this variant is not present. We have observed this variant in the Shriners Hospital for Children variant database in seven individuals with a diagnosis of osteogenesis imperfecta.

Nov 16, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change affects a donor splice site in intron 26 of the COL1A1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in COL1A1 are known to be pathogenic (PMID: 7942841, 9295084, 9443882). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individuals with osteogenesis imperfecta (PMID: 8408653, 9067755, 10931857, 15931785, 17078022). This variant is also known as IVS26+1G>A. ClinVar contains an entry for this variant (Variation ID: 425580). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic.

Oct 01, 1993

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

May 28, 2019

Mendelics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

not provided

Pathogenic:4

Apr 23, 2018

Athena Diagnostics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Dec 27, 2023

Revvity Omics, Revvity

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Dec 06, 2023

Clinical Genetics Laboratory, Skane University Hospital Lund

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Jul 19, 2022

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Canonical splice site variant in a gene for which loss-of-function is a known mechanism of disease (Stover et al., 1993); Not observed in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 25944380, 8408653, 25525159, 10931857, 9295084, 7942841, 9443882, 30614853, 9067755, 28810924, 33470886, 33939306, 17078022, 15931785)

Osteogenesis imperfecta

Pathogenic:1

Apr 10, 2022

DASA

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.1821+1G>A variant is located in a canonical splice-site, and it is not predicted the protein reading frame alteration, however, occur in a critical region and the variant disrupts <10% of protein - PVS1_moderate. Well-established in vitro or in vivo functional studies supportive of a damaging effect on the gene or gene product (PMID: 8408653) - PS3_moderate. This sequence change has been observed in affected individual(s) and ClinVar contains an entry for this variant (Clinvar ID:425580; PMID: 33939306; PMID: 33928192; PMID: 28810924; PMID: 32166892) - PS4. This variant is not present in population databases (rs66555264- gnomAD; ABraOM no frequency - http://abraom.ib.usp.br) - PM2. The variant co-segregated with disease in multiple affected family members (PMID: 33928192; 33228694) - PP1_strong. In summary, the currently available evidence indicates that the variant is pathogenic

Infantile cortical hyperostosis;C0023931:Osteogenesis imperfecta type I;C0029458:Postmenopausal osteoporosis;C0268358:Osteogenesis imperfecta, perinatal lethal;C0268362:Osteogenesis imperfecta type III;C0268363:Osteogenesis imperfecta with normal sclerae, dominant form;C4551623:Ehlers-Danlos syndrome, arthrochalasia type

Pathogenic:1

Oct 31, 2018

Fulgent Genetics, Fulgent Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

COL1A1-related disorder

Pathogenic:1

Jul 13, 2023

PreventionGenetics, part of Exact Sciences

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The COL1A1 c.1821+1G>A variant is predicted to disrupt the GT donor site and interfere with normal splicing. This variant was reported to be causative for osteogenesis imperfecta (Stover et al. 1993. PubMed ID: 8408653; Zhytnik et al. 2020. PubMed ID: 32166892; Higuchi et al. 2021. PubMed ID: 33939306). mRNA studies showed that this variant results in intron 26 retention leading to a frameshift and premature protein termination (Stover et al. 1993. PubMed ID: 8408653). This variant has not been reported in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. Variants that disrupt the consensus splice donor site in COL1A1 are expected to be pathogenic. This variant is interpreted as pathogenic.

Cardiovascular phenotype

Pathogenic:1

Jul 02, 2024

Ambry Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.1821+1G>A intronic pathogenic mutation results from a G to A substitution one nucleotide after coding exon 26 of the COL1A1 gene. Alterations that disrupt the canonical splice site are expected to result in aberrant splicing. In silico splice site analysis predicts that this alteration will weaken the native splice donor site and will result in the creation or strengthening of a novel splice donor site. The resulting transcript is predicted to be in-frame and is not expected to trigger nonsense-mediated mRNAdecay; however, direct evidence is unavailable. The exact functional effect of the altered amino acid sequence is unknown. This mutation has been reported in multiple subjects with osteogenesis imperfecta (OI) including a de novo occurrence (Körkkö J et al. Hum Mutat, 1997;9:148-56; Stover ML et al. J Clin Invest, 1993 Oct;92:1994-2002; Higuchi Y et al. Mol Genet Genomic Med, 2021 Jun;9:e1675; Holtz AP et al. Bone, 2023 Apr;169:116683; Mei Y et al. Front Endocrinol (Lausanne), 2022 Jul;13:935905). This variant has also been reported to segregate with disease in two families with OI (Zhytnik L et al. BMC Med Genomics, 2020 Nov;13:177; Doolan E et al. BMJ Open Ophthalmol, 2021 Apr;6:e000684). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). This nucleotide position is highly conserved in available vertebrate species. Based on the supporting evidence, this variant is interpreted as a disease-causing mutation.

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.60

BayesDel_noAF

Pathogenic

0.38

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

0.88

FATHMM_MKL

Uncertain

0.95

PhyloP100

4.5

GERP RS

4.7

Mutation Taster

=0/100

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.93

SpliceAI score (max)

0.96

Details are displayed if max score is > 0.2

DS_DG_spliceai

0.78

Position offset: -3

DS_DL_spliceai

0.96

Position offset: 1

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over