21-45476355-C-T

Variant names:

Variant summary

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

The NM_001379500.1(COL18A1):c.803C>T(p.Ala268Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000128 in 1,613,876 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A268T) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00013 ( 0 hom. )

Consequence

COL18A1
NM_001379500.1 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: -1.10

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: Likely_benign. The variant received -4 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.05446616).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL18A1	NM_001379500.1 link	c.803C>T	p.Ala268Val	missense_variant	Exon 6 of 42	ENST00000651438.1	NP_001366429.1
COL18A1	NM_130444.3 link	c.2048C>T	p.Ala683Val	missense_variant	Exon 5 of 41		NP_569711.2	P39060
COL18A1	NM_030582.4 link	c.1343C>T	p.Ala448Val	missense_variant	Exon 5 of 41		NP_085059.2	P39060D3DSM5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
COL18A1	ENST00000651438.1 link	c.803C>T	p.Ala268Val	missense_variant	Exon 6 of 42		NM_001379500.1	ENSP00000498485.1	P39060-2
COL18A1	ENST00000355480.10 link	c.1343C>T	p.Ala448Val	missense_variant	Exon 5 of 41	1		ENSP00000347665.5	P39060-1
COL18A1	ENST00000359759.8 link	c.2048C>T	p.Ala683Val	missense_variant	Exon 5 of 41	5		ENSP00000352798.4	P39060-3

Frequencies

GnomAD3 genomes

AF:

0.0000657

AC:

AN:

152256

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000414

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000118

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000969

AC:

AN:

247674

AF XY:

0.000111

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000580

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000134

Gnomad OTH exome

AF:

0.000497

GnomAD4 exome

AF:

0.000135

AC:

197

AN:

1461620

Hom.:

Cov.:

AF XY:

0.000139

AC XY:

101

AN XY:

727122

show subpopulations

African (AFR)

AF:

0.0000598

AC:

AN:

33470

American (AMR)

AF:

0.0000671

AC:

AN:

44716

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.0000252

AC:

AN:

39700

South Asian (SAS)

AF:

0.000116

AC:

AN:

86252

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53274

Middle Eastern (MID)

AF:

0.000173

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.000150

AC:

167

AN:

1111934

Other (OTH)

AF:

0.000215

AC:

AN:

60376

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.463

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:

0.0000657

AC:

AN:

152256

Hom.:

Cov.:

AF XY:

0.0000672

AC XY:

AN XY:

74382

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41472

American (AMR)

AF:

0.00

AC:

AN:

15290

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5190

South Asian (SAS)

AF:

0.000414

AC:

AN:

4834

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10628

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.000118

AC:

AN:

68048

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.515

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:

0.0000819

Hom.:

Bravo

AF:

0.0000642

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000121

AC:

ExAC

AF:

0.000107

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

EpiCase

AF:

0.000382

EpiControl

AF:

0.000237

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not specified

Uncertain:1

Jan 23, 2017

Athena Diagnostics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not provided

Uncertain:1

Oct 17, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 268 of the COL18A1 protein (p.Ala268Val). This variant is present in population databases (rs375414087, gnomAD 0.01%). This variant has not been reported in the literature in individuals affected with COL18A1-related conditions. ClinVar contains an entry for this variant (Variation ID: 447135). Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

COL18A1-related disorder

Uncertain:1

Oct 10, 2023

PreventionGenetics, part of Exact Sciences

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The COL18A1 c.1343C>T variant is predicted to result in the amino acid substitution p.Ala448Val. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.013% of alleles in individuals of South Asian descent in gnomAD (http://gnomad.broadinstitute.org/variant/21-46896269-C-T). At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.074

BayesDel_addAF

Benign

-0.34

BayesDel_noAF

Benign

-0.48

CADD

Benign

1.3

(source)

DANN

Benign

0.87

DEOGEN2

Benign

0.018

.;.;T

Eigen

Benign

-1.3

Eigen_PC

Benign

-1.3

FATHMM_MKL

Benign

0.029

LIST_S2

Benign

0.30

T;T;T

M_CAP

Benign

0.070

MetaRNN

Benign

0.054

T;T;T

MetaSVM

Benign

-0.56

MutationAssessor

Benign

0.41

.;.;N

PhyloP100

-1.1

PrimateAI

Uncertain

0.49

PROVEAN

Benign

-0.80

N;N;N

REVEL

Benign

0.13

Sift

Benign

0.36

T;T;T

Sift4G

Benign

0.59

T;T;T

Polyphen

0.0010

B;B;B

Vest4

0.097

MVP

0.67

MPC

0.067

ClinPred

0.015

GERP RS

0.80

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.015

gMVP

0.26

Mutation Taster

=99/1

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

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

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over