17-50187014-C-T

Variant names:

• chr17-50187014-C-T
• rs72656326
• NM_000088.4:c.3531+1G>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_000088.4(COL1A1):​c.3531+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. 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: 32)
• Consequence: COL1A1 NM_000088.4 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 7.84
• Publications: 1 publications found

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

ACMG classification

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 0.024573378 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 17-50187014-C-T is Pathogenic according to our data. Variant chr17-50187014-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 568906.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.3531+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.3531+1G>A		splice_donor intron	N/A	ENSP00000225964.6
	COL1A1	ENST00000510710.3	TSL:2	n.109G>A		non_coding_transcript_exon	Exon 1 of 2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Osteogenesis imperfecta Pathogenic:2

Nov 19, 2021

Illumina Laboratory Services, Illumina

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The COL1A1 c.3531+1G>A variant occurs in a canonical splice site (donor) and is predicted to disrupt the normal gene product. The c.3531+1G>A variant has been reported in a heterozygous state in an individual with osteogenesis imperfecta, type I (Willing et al. 1994). The c.3531+1G>A variant is not found in version 2.1.1 or version 3.1.2 of the Genome Aggregation Database despite its location in a region of good sequencing coverage, which suggests the variant is rare. Experimental studies have shown that the variant leads to preservation of the reading frame with skipping of exon 48 and reduced mRNA levels (Willing et al. 1994). Other nucleotides changes at this same position have been reported in at least three individuals with osteogenesis imperfecta (Bardai et al. 2016; Essawi et al. 2018). Based on the collective evidence, the c.3531+1G>A variant is classified as pathogenic for COL1A1-related osteogenesis imperfecta.

Nov 06, 2018

Genome Diagnostics Laboratory, The Hospital for Sick Children

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Osteogenesis imperfecta type I Pathogenic:1

Mar 14, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. Donor and acceptor splice site variants 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). Experimental studies have shown that this splice variant leads to skipping of exon 48 and reduced mRNA levels (PMID: 7942841). This variant has been reported in an individual affected with osteogenesis imperfecta type I (PMID: 7942841). The variant is also known as a substitution at the 5' donor splice site at position +1 of intron 48. This variant is not present in population databases (ExAC no frequency). This sequence change affects a donor splice site in intron 47 of the COL1A1 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.60	D
BayesDel_noAF	Pathogenic	0.22
CADD	Pathogenic	32
DANN	Uncertain	0.99
Eigen	Pathogenic	0.98
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Uncertain	0.97	D
PhyloP100		7.8
GERP RS		3.4
Mutation Taster		=2/98	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.91
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.97		Position offset: 1

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

Other links and lift over

dbSNP: rs72656326; hg19: chr17-48264375;