21-45509639-C-T

Variant names:

• chr21-45509639-C-T
• rs78487064
• NM_001379500.1:c.3495+38C>T

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_001379500.1(COL18A1):​c.3495+38C>T variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000106 in 941,998 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 0.0000011 (0 hom.)
• Consequence: COL18A1 NM_001379500.1 intron
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.459
• Publications: 0 publications found

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]

SLC19A1 (HGNC:10937): (solute carrier family 19 member 1) The membrane protein encoded by this gene is a transporter of folate and is involved in the regulation of intracellular concentrations of folate. Three transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Mar 2011]

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.81).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001379500.1. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL18A1	NM_001379500.1	MANE Select	c.3495+38C>T		intron	N/A	NP_001366429.1
	COL18A1	NM_130444.3		c.4740+38C>T		intron	N/A	NP_569711.2
	COL18A1	NM_030582.4		c.4035+38C>T		intron	N/A	NP_085059.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL18A1	ENST00000651438.1	MANE Select	c.3495+38C>T		intron	N/A	ENSP00000498485.1
	COL18A1	ENST00000355480.10	TSL:1	c.4035+38C>T		intron	N/A	ENSP00000347665.5
	SLC19A1	ENST00000567670.5	TSL:1	c.1294-11027G>A		intron	N/A	ENSP00000457278.1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 0.00000106 AC: 1 AN: 941998 Hom.: 0 Cov.: 13 AF XY: 0.00 AC XY: 0 AN XY: 482222

African (AFR) AF: 0.00 AC: 0 AN: 23314

American (AMR) AF: 0.00 AC: 0 AN: 35170

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 22356

East Asian (EAS) AF: 0.00 AC: 0 AN: 33828

South Asian (SAS) AF: 0.00 AC: 0 AN: 70588

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 33568

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4200

European-Non Finnish (NFE) AF: 0.00000148 AC: 1 AN: 675644

Other (OTH) AF: 0.00 AC: 0 AN: 43330

GnomAD4 genome Cov.: 34

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.81
CADD	Benign	2.3
DANN	Benign	0.69
PhyloP100		-0.46

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

Other links and lift over

dbSNP: rs78487064; hg19: chr21-46929553;