rs778612831

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PVS1_ModeratePP5_Moderate

The NM_001379500.1(COL18A1):c.1897-2A>G variant causes a splice acceptor, intron change. The variant allele was found at a frequency of 0.00000372 in 1,613,732 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000034 ( 0 hom. )

Consequence

COL18A1
NM_001379500.1 splice_acceptor, intron

Scores

Clinical Significance

Likely pathogenic criteria provided, single submitter P:2

Conservation

PhyloP100: 4.00

Publications

0 publications found

Variant links:

Genes affected

COL18A1 (HGNC:2195): (collagen type XVIII alpha 1 chain) This gene encodes the alpha chain of type XVIII collagen. This collagen is one of the multiplexins, extracellular matrix proteins that contain multiple triple-helix domains (collagenous domains) interrupted by non-collagenous domains. A long isoform of the protein has an N-terminal domain that is homologous to the extracellular part of frizzled receptors. Proteolytic processing at several endogenous cleavage sites in the C-terminal domain results in production of endostatin, a potent antiangiogenic protein that is able to inhibit angiogenesis and tumor growth. Mutations in this gene are associated with Knobloch syndrome. The main features of this syndrome involve retinal abnormalities, so type XVIII collagen may play an important role in retinal structure and in neural tube closure. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Dec 2014]

COL18A1 Gene-Disease associations (from GenCC):

Knobloch syndrome 1
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, G2P
Knobloch syndrome
Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Laboratory for Molecular Medicine, Orphanet
hereditary glaucoma, primary closed-angle
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

COL18A1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.006716418 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.

PP5

Variant 21-45488416-A-G is Pathogenic according to our data. Variant chr21-45488416-A-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 438060.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	Effect	Exon rank	MANE	Protein
COL18A1	NM_001379500.1 link	c.1897-2A>G	splice_acceptor_variant, intron_variant	Intron 17 of 41	ENST00000651438.1	NP_001366429.1
COL18A1	NM_130444.3 link	c.3142-2A>G	splice_acceptor_variant, intron_variant	Intron 16 of 40		NP_569711.2
COL18A1	NM_030582.4 link	c.2437-2A>G	splice_acceptor_variant, intron_variant	Intron 16 of 40		NP_085059.2

Ensembl

Gene	Transcript	HGVSc	Effect	Exon rank	TSL	MANE	Protein
COL18A1	ENST00000651438.1 link	c.1897-2A>G	splice_acceptor_variant, intron_variant	Intron 17 of 41		NM_001379500.1	ENSP00000498485.1
COL18A1	ENST00000355480.10 link	c.2437-2A>G	splice_acceptor_variant, intron_variant	Intron 16 of 40	1		ENSP00000347665.5
COL18A1	ENST00000359759.8 link	c.3142-2A>G	splice_acceptor_variant, intron_variant	Intron 16 of 40	5		ENSP00000352798.4

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152172

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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

GnomAD2 exomes

AF:

0.00000401

AC:

AN:

249218

AF XY:

0.00000739

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000342

AC:

AN:

1461560

Hom.:

Cov.:

AF XY:

0.00000413

AC XY:

AN XY:

727056

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53146

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000270

AC:

AN:

1111970

Other (OTH)

AF:

0.00

AC:

AN:

60378

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.495

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152172

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74348

show subpopulations

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.0000241

AC:

AN:

41438

American (AMR)

AF:

0.00

AC:

AN:

15286

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5170

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68032

Other (OTH)

AF:

0.00

AC:

AN:

2090

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ExAC

AF:

0.00000827

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

not provided

Pathogenic:1

Oct 23, 2020

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Retinal dystrophy

Pathogenic:1

Jan 01, 2015

NIHR Bioresource Rare Diseases, University of Cambridge

Significance:Likely pathogenic

Review Status:no assertion criteria provided

Collection Method:research

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.56

BayesDel_noAF

Benign

-0.28

CADD

Benign

(source)

DANN

Benign

0.93

DEOGEN2

Benign

0.0

.;.;.

Eigen

Pathogenic

0.69

Eigen_PC

Uncertain

0.41

FATHMM_MKL

Uncertain

0.91

LIST_S2

Benign

0.0

.;.;.

MetaRNN

Benign

0.0

.;.;.

MutationAssessor

Benign

0.0

.;.;.

PhyloP100

4.0

PROVEAN

Benign

0.0

.;.;.

REVEL

Benign

0.0

Sift

Pathogenic

0.0

.;.;.

Sift4G

Pathogenic

0.0

.;.;.

Vest4

0.0

GERP RS

3.4

Mutation Taster

=9/91

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.99

Details are displayed if max score is > 0.2

DS_AL_spliceai

0.99

Position offset: 2

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

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over