chr20-62828772-G-T

Variant names:

• chr20-62828772-G-T
• rs2249903
• NM_001853.4:c.909G>T

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_001853.4(COL9A3):​c.909G>T​(p.Pro303Pro) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. P303P) has been classified as Benign.

• Frequency: Genomes: not found (cov: 35)
• Consequence: COL9A3 NM_001853.4 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -1.89
• Publications: 18 publications found

Genes affected

COL9A3 (HGNC:2219): (collagen type IX alpha 3 chain) This gene encodes one of the three alpha chains of type IX collagen, the major collagen component of hyaline cartilage. Type IX collagen, a heterotrimeric molecule, is usually found in tissues containing type II collagen, a fibrillar collagen. Mutations in this gene are associated with multiple epiphyseal dysplasia type 3. [provided by RefSeq, Jan 2010]

COL9A3 Gene-Disease associations (from GenCC):

• epiphyseal dysplasia, multiple, 3

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Illumina, Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
• Stickler syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, LIMITED Submitted by: ClinGen, Ambry Genetics, Genomics England PanelApp
• Stickler syndrome, type 6

  Inheritance: AR Classification: DEFINITIVE, STRONG, LIMITED Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
• multiple epiphyseal dysplasia due to collagen 9 anomaly

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• autosomal recessive Stickler syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.48).
• BP7: Synonymous conserved (PhyloP=-1.89 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001853.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL9A3	NM_001853.4	MANE Select	c.909G>T	p.Pro303Pro	synonymous	Exon 18 of 32	NP_001844.3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL9A3	ENST00000649368.1	MANE Select	c.909G>T	p.Pro303Pro	synonymous	Exon 18 of 32	ENSP00000496793.1	Q14050
	COL9A3	ENST00000934236.1		c.960G>T	p.Pro320Pro	synonymous	Exon 19 of 33	ENSP00000604295.1
	COL9A3	ENST00000894732.1		c.837G>T	p.Pro279Pro	synonymous	Exon 17 of 31	ENSP00000564791.1

Frequencies

GnomAD3 genomes Cov.: 35

GnomAD4 exome Cov.: 42

GnomAD4 genome Cov.: 35

Alfa AF: 0.00 Hom.: 1236

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.48
CADD	Benign	0.57
DANN	Benign	0.82
PhyloP100		-1.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

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: rs2249903; hg19: chr20-61460124;