rs72658164

Positions:

• chr7-94420292-T-A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 10P and 1B. PM2 PP5_Very_Strong BP4

The NM_000089.4(COL1A2):​c.2133+6T>A variant causes a splice donor region, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL1A2 NM_000089.4 splice_donor_region, intron
• Scores: Splicing: ADA: 0.9924
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 4.63

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 Likely_pathogenic. Variant got 9 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-94420292-T-A is Pathogenic according to our data. Variant chr7-94420292-T-A is described in ClinVar as [Pathogenic]. Clinvar id is 456815.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.44). . Strength limited to SUPPORTING due to the PP5.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL1A2	NM_000089.4	c.2133+6T>A		splice_donor_region_variant, intron_variant		ENST00000297268.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL1A2	ENST00000297268.11	c.2133+6T>A		splice_donor_region_variant, intron_variant		1	NM_000089.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Osteogenesis imperfecta, perinatal lethal Pathogenic:1

Pathogenic, criteria provided, single submitter

in vitro

Medical Genetics Laboratory, West China Hospital, Sichuan University

-

The clinical manifestation of the proband and his family members- the lower limbs are bent out of shape and/or has enamel defect. In vitro Minigene studies indicate that the variants interrupted its normal splicing process . -

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

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Nov 28, 2022

For these reasons, this variant has been classified as Pathogenic. 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). 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 35, but is expected to preserve the integrity of the reading-frame (PMID: 16705691). ClinVar contains an entry for this variant (Variation ID: 456815). This variant has been observed in individual(s) with autosomal dominant osteogenesis imperfecta (PMID: 16705691, 30715774). This variant is not present in population databases (gnomAD no frequency). This sequence change falls in intron 35 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.44
CADD	Benign	19
DANN	Benign	0.91

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.99
dbscSNV1_RF	Benign	0.64
SpliceAI score (max)		0.010		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: rs72658164; hg19: chr7-94049604;