21-45405236-GC-G

Variant names:

• chr21-45405236-GC-G
• NM_001379500.1:c.8delC

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PVS1_Strong PP5_Moderate

The NM_001379500.1(COL18A1):​c.8delC​(p.Pro3ArgfsTer121) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 0)
• Consequence: COL18A1 NM_001379500.1 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 0.495

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 Likely_pathogenic. Variant got 6 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 6 pathogenic variants in the truncated region.
• PP5: Variant 21-45405236-GC-G is Pathogenic according to our data. Variant chr21-45405236-GC-G is described in ClinVar as [Pathogenic]. Clinvar id is 1452520.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.8delC	p.Pro3ArgfsTer121	frameshift_variant	Exon 1 of 42	ENST00000651438.1	NP_001366429.1
BNAT1	NR_183526.1	n.197-741delG		intron_variant	Intron 1 of 1
BNAT1	NR_183527.1	n.181+123delG		intron_variant	Intron 1 of 1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL18A1	ENST00000651438.1	c.8delC	p.Pro3ArgfsTer121	frameshift_variant	Exon 1 of 42		NM_001379500.1	ENSP00000498485.1

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD4 exome Cov.: 3

GnomAD4 genome Cov.: 0

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Nov 28, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Pro3Argfs*121) in the COL18A1 gene. It is expected to result in an absent or disrupted protein product. 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. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

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: chr21-46825151;