21-45468376-C-T

Variant names:

Variant summary

Our verdict is Benign. The variant received -20 ACMG points: 0P and 20B. BP4_StrongBP6_Very_StrongBS1BS2

The NM_001379500.1(COL18A1):c.241C>T(p.Arg81Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00193 in 1,613,832 control chromosomes in the GnomAD database, including 58 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R81Q) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.010 ( 31 hom., cov: 34)

Exomes 𝑓: 0.0011 ( 27 hom. )

Consequence

COL18A1
NM_001379500.1 missense

Scores

Clinical Significance

Benign/Likely benign criteria provided, multiple submitters, no conflicts B:5

Conservation

PhyloP100: 2.32

Publications

5 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: Benign. The variant received -20 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.005399853).

BP6

Variant 21-45468376-C-T is Benign according to our data. Variant chr21-45468376-C-T is described in ClinVar as Benign/Likely_benign. ClinVar VariationId is 235468.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

BS1

Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.0102 (1549/152364) while in subpopulation AFR AF = 0.0346 (1439/41590). AF 95% confidence interval is 0.0331. There are 31 homozygotes in GnomAd4. There are 749 alleles in the male GnomAd4 subpopulation. Median coverage is 34. This position passed quality control check.

BS2

High Homozygotes in GnomAd4 at 31 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein
COL18A1	NM_001379500.1 link	c.241C>T	p.Arg81Trp	missense_variant	Exon 3 of 42	ENST00000651438.1	NP_001366429.1
COL18A1	NM_130444.3 link	c.1486C>T	p.Arg496Trp	missense_variant	Exon 2 of 41		NP_569711.2
COL18A1	NM_030582.4 link	c.781C>T	p.Arg261Trp	missense_variant	Exon 2 of 41		NP_085059.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein
COL18A1	ENST00000651438.1 link	c.241C>T	p.Arg81Trp	missense_variant	Exon 3 of 42		NM_001379500.1	ENSP00000498485.1
COL18A1	ENST00000355480.10 link	c.781C>T	p.Arg261Trp	missense_variant	Exon 2 of 41	1		ENSP00000347665.5
COL18A1	ENST00000359759.8 link	c.1486C>T	p.Arg496Trp	missense_variant	Exon 2 of 41	5		ENSP00000352798.4

Frequencies

GnomAD3 genomes

AF:

0.0102

AC:

1546

AN:

152246

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0346

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00556

Gnomad ASJ

AF:

0.000288

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000414

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000588

Gnomad OTH

AF:

0.00860

GnomAD2 exomes

AF:

0.00243

AC:

607

AN:

249458

AF XY:

0.00178

show subpopulations

Gnomad AFR exome

AF:

0.0342

Gnomad AMR exome

AF:

0.00154

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000795

Gnomad OTH exome

AF:

0.00132

GnomAD4 exome

AF:

0.00107

AC:

1563

AN:

1461468

Hom.:

Cov.:

AF XY:

0.000893

AC XY:

649

AN XY:

727052

show subpopulations

African (AFR)

AF:

0.0371

AC:

1242

AN:

33480

American (AMR)

AF:

0.00197

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.0000383

AC:

AN:

26134

East Asian (EAS)

AF:

0.0000252

AC:

AN:

39698

South Asian (SAS)

AF:

0.000220

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53002

Middle Eastern (MID)

AF:

0.00139

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000486

AC:

AN:

1112010

Other (OTH)

AF:

0.00248

AC:

150

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.466

Heterozygous variant carriers

112

224

336

448

560

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

Variant carriers

126

168

210

<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:

0.0102

AC:

1549

AN:

152364

Hom.:

Cov.:

AF XY:

0.0101

AC XY:

749

AN XY:

74508

show subpopulations

African (AFR)

AF:

0.0346

AC:

1439

AN:

41590

American (AMR)

AF:

0.00555

AC:

AN:

15312

Ashkenazi Jewish (ASJ)

AF:

0.000288

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5180

South Asian (SAS)

AF:

0.000414

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10622

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000588

AC:

AN:

68036

Other (OTH)

AF:

0.00851

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.498

Heterozygous variant carriers

156

234

312

390

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Genome Hom

Variant carriers

100

<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:

0.00227

Hom.:

Bravo

AF:

0.0116

ESP6500AA

AF:

0.0317

AC:

130

ESP6500EA

AF:

0.000119

AC:

ExAC

AF:

0.00301

AC:

364

Asia WGS

AF:

0.00173

AC:

AN:

3478

EpiCase

AF:

0.000164

EpiControl

AF:

0.000296

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:5

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Benign:3

Feb 03, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Sep 25, 2015

Center for Pediatric Genomic Medicine, Children's Mercy Hospital and Clinics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Breakthrough Genomics, Breakthrough Genomics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:not provided

not specified

Benign:1

Dec 25, 2018

Genetic Services Laboratory, University of Chicago

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Knobloch syndrome

Benign:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease.

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.12

BayesDel_addAF

Benign

-0.49

BayesDel_noAF

Benign

-0.45

CADD

Benign

(source)

DANN

Uncertain

1.0

DEOGEN2

Benign

0.0

.;.;T

Eigen

Uncertain

0.25

Eigen_PC

Benign

0.14

FATHMM_MKL

Benign

0.55

LIST_S2

Uncertain

0.90

D;D;D

MetaRNN

Benign

0.0054

T;T;T

MetaSVM

Benign

-0.90

MutationAssessor

Benign

0.0

.;.;M

PhyloP100

2.3

PrimateAI

Benign

0.24

PROVEAN

Uncertain

-4.4

D;D;D

REVEL

Benign

0.15

Sift

Uncertain

0.0040

D;D;D

Sift4G

Uncertain

0.012

D;D;D

Vest4

0.52

ClinPred

0.022

GERP RS

4.7

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.23

gMVP

0.58

Mutation Taster

=93/7

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

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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