21-45405242-G-A

Variant names:

• chr21-45405242-G-A
• NM_001379500.1:c.11+1G>A

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1 PP5_Moderate

The NM_001379500.1(COL18A1):​c.11+1G>A variant causes a splice donor, intron change involving the alteration of a non-conserved nucleotide. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 0)
  • Exomes 𝑓: 0.000011 (0 hom.)
• Consequence: COL18A1 NM_001379500.1 splice_donor, intron
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: -0.490

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]

BNAT1 (HGNC:56666): (breast cancer associated ESR1 regulating natural antisense transcript 1)

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PP5: Variant 21-45405242-G-A is Pathogenic according to our data. Variant chr21-45405242-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 3725383.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL18A1	NM_001379500.1	c.11+1G>A		splice_donor_variant, intron_variant	Intron 1 of 41	ENST00000651438.1	NP_001366429.1
BNAT1	NR_183526.1	n.197-746C>T		intron_variant	Intron 1 of 1
BNAT1	NR_183527.1	n.181+118C>T		intron_variant	Intron 1 of 1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL18A1	ENST00000651438.1	c.11+1G>A		splice_donor_variant, intron_variant	Intron 1 of 41		NM_001379500.1	ENSP00000498485.1

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD4 exome AF: 0.0000106 AC: 1 AN: 94752 Hom.: 0 Cov.: 3 AF XY: 0.0000203 AC XY: 1 AN XY: 49144

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000155

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 0

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Nov 16, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 1 of the COL18A1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in COL18A1 are known to be pathogenic (PMID: 12415512, 25456301). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with COL18A1-related conditions. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.13	T
BayesDel_noAF	Benign	-0.42
CADD	Benign	23
DANN	Benign	0.93
Eigen	Benign	-0.44
Eigen_PC	Benign	-0.58
FATHMM_MKL	Benign	0.028	N
GERP RS		1.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.2

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr21-46825157;