Genetic Variant COL18A1:c.1834-23C>T (chr21-45487424-C-T) – ACMG Classification: Likely_benign (-4 pts)

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BP4_Strong

The NM_001379500.1(COL18A1):c.1834-23C>T variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000931 in 1,611,412 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. There are indicators that this mutation may affect the branch point..

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000062 ( 0 hom. )

Consequence

COL18A1
NM_001379500.1 intron

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -3.20

Publications

7 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: Likely_benign. The variant received -4 ACMG points.

BP4

This position, referring to a specific DNA site, is a probable branch point but is likely benign (scored 1 / 10, using the threshold of <=3). The score ranges from 0 to 10, with values ≤3 considered benign and >5 classified as pathogenic. Computational evidence support a benign effect (BayesDel_noAF=-0.94).

Transcripts

RefSeq

Gene	Transcript	HGVSc	Effect	Exon rank	MANE	Protein
COL18A1	NM_001379500.1 link	c.1834-23C>T	intron_variant	Intron 16 of 41	ENST00000651438.1	NP_001366429.1
COL18A1	NM_130444.3 link	c.3079-23C>T	intron_variant	Intron 15 of 40		NP_569711.2
COL18A1	NM_030582.4 link	c.2374-23C>T	intron_variant	Intron 15 of 40		NP_085059.2

Ensembl

Gene	Transcript	HGVSc	Effect	Exon rank	TSL	MANE	Protein
COL18A1	ENST00000651438.1 link	c.1834-23C>T	intron_variant	Intron 16 of 41		NM_001379500.1	ENSP00000498485.1
COL18A1	ENST00000355480.10 link	c.2374-23C>T	intron_variant	Intron 15 of 40	1		ENSP00000347665.5
COL18A1	ENST00000359759.8 link	c.3079-23C>T	intron_variant	Intron 15 of 40	5		ENSP00000352798.4

Frequencies

GnomAD3 genomes

AF:

0.0000394

AC:

AN:

152154

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000121

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:

0.0000941

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000161

AC:

AN:

247794

AF XY:

0.00000742

show subpopulations

Gnomad AFR exome

AF:

0.0000651

Gnomad AMR exome

AF:

0.0000290

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.0000482

Gnomad NFE exome

AF:

0.00000888

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000617

AC:

AN:

1459258

Hom.:

Cov.:

AF XY:

0.00000551

AC XY:

AN XY:

725948

show subpopulations

African (AFR)

AF:

0.0000896

AC:

AN:

33464

American (AMR)

AF:

0.0000224

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26130

East Asian (EAS)

AF:

0.00

AC:

AN:

39692

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86230

European-Finnish (FIN)

AF:

0.0000193

AC:

AN:

51818

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5360

European-Non Finnish (NFE)

AF:

0.00000180

AC:

AN:

1111532

Other (OTH)

AF:

0.0000166

AC:

AN:

60310

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.453

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:

0.0000394

AC:

AN:

152154

Hom.:

Cov.:

AF XY:

0.0000673

AC XY:

AN XY:

74324

show subpopulations

African (AFR)

AF:

0.000121

AC:

AN:

41426

American (AMR)

AF:

0.00

AC:

AN:

15294

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5168

South Asian (SAS)

AF:

0.00

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.0000941

AC:

AN:

10630

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68018

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.433

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.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.94

CADD

Benign

0.19

(source)

DANN

Benign

0.66

PhyloP100

-3.2

BranchPoint Hunter

1.0

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Splicing

Name

Calibrated prediction

Score

Prediction

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

You must be logged in to view publications. This limit was set because tens of millions (!) of queries from AI bots are generated daily.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over