rs753322378

Positions:

• chr21-45480092-GAGGGCCCCCAGGACCCCA-G

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM4

The NM_001379500.1(COL18A1):​c.1341_1358del​(p.Gln451_Pro456del) variant causes a inframe deletion change. The variant allele was found at a frequency of 0.0000137 in 1,457,936 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000014 (0 hom.)
• Consequence: COL18A1 NM_001379500.1 inframe_deletion
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 6.32

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM4: Nonframeshift variant in NON repetitive region in NM_001379500.1.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL18A1	NM_001379500.1	c.1341_1358del	p.Gln451_Pro456del	inframe_deletion	11/42	ENST00000651438.1
COL18A1	NM_030582.4	c.1881_1898del	p.Gln631_Pro636del	inframe_deletion	10/41
COL18A1	NM_130444.3	c.2586_2603del	p.Gln866_Pro871del	inframe_deletion	10/41

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL18A1	ENST00000651438.1	c.1341_1358del	p.Gln451_Pro456del	inframe_deletion	11/42		NM_001379500.1
COL18A1	ENST00000355480.10	c.1881_1898del	p.Gln631_Pro636del	inframe_deletion	10/41	1
COL18A1	ENST00000359759.8	c.2586_2603del	p.Gln866_Pro871del	inframe_deletion	10/41	5		P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000811 AC: 2 AN: 246754 Hom.: 0 AF XY: 0.0000149 AC XY: 2 AN XY: 134172

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000111

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000137 AC: 20 AN: 1457936 Hom.: 0 AF XY: 0.0000124 AC XY: 9 AN XY: 725530

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000302

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000722

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Athena Diagnostics

Jul 05, 2017

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jul 12, 2022

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. Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. ClinVar contains an entry for this variant (Variation ID: 447112). This variant has not been reported in the literature in individuals affected with COL18A1-related conditions. This variant is present in population databases (rs753322378, gnomAD 0.01%). This variant, c.1341_1358del, results in the deletion of 6 amino acid(s) of the COL18A1 protein (p.Gln451_Pro456del), but otherwise preserves the integrity of the reading frame. -

Computational scores

Source: dbNSFP v4.3

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs753322378; hg19: chr21-46900006;