6-70281033-G-T

Variant names:

• chr6-70281033-G-T
• rs121912931
• NM_001851.6:c.883C>A

Variant summary

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

The NM_001851.6(COL9A1):​c.883C>A​(p.Arg295Arg) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,156 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: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: COL9A1 NM_001851.6 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.98
• Publications: 7 publications found

Genes affected

COL9A1 (HGNC:2217): (collagen type IX alpha 1 chain) This gene encodes one of the three alpha chains of type IX collagen, which is a minor (5-20%) collagen component of hyaline cartilage. Type IX collagen is usually found in tissues containing type II collagen, a fibrillar collagen. Studies in knockout mice have shown that synthesis of the alpha 1 chain is essential for assembly of type IX collagen molecules, a heterotrimeric molecule, and that lack of type IX collagen is associated with early onset osteoarthritis. Mutations in this gene are associated with osteoarthritis in humans, with multiple epiphyseal dysplasia, 6, a form of chondrodysplasia, and with Stickler syndrome, a disease characterized by ophthalmic, orofacial, articular, and auditory defects. Two transcript variants that encode different isoforms have been identified for this gene. [provided by RefSeq, Jul 2008]

COL9A1 Gene-Disease associations (from GenCC):

• epiphyseal dysplasia, multiple, 6

  Inheritance: AD, AR, Unknown Classification: DEFINITIVE, LIMITED Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• Stickler syndrome, type 4

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Ambry Genetics, G2P, Genomics England PanelApp, PanelApp Australia, Labcorp Genetics (formerly Invitae)
• 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
• Stickler syndrome

  Inheritance: AR Classification: LIMITED Submitted by: ClinGen

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=-0.52).
• BP7: Synonymous conserved (PhyloP=1.98 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001851.6. 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
	COL9A1	NM_001851.6	MANE Select	c.883C>A	p.Arg295Arg	synonymous	Exon 9 of 38	NP_001842.3
	COL9A1	NM_001377289.1		c.154C>A	p.Arg52Arg	synonymous	Exon 3 of 33	NP_001364218.1
	COL9A1	NM_078485.4		c.154C>A	p.Arg52Arg	synonymous	Exon 3 of 32	NP_511040.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL9A1	ENST00000357250.11	TSL:1 MANE Select	c.883C>A	p.Arg295Arg	synonymous	Exon 9 of 38	ENSP00000349790.6
	COL9A1	ENST00000320755.12	TSL:1	c.154C>A	p.Arg52Arg	synonymous	Exon 3 of 32	ENSP00000315252.7
	COL9A1	ENST00000370496.3	TSL:1	c.883C>A	p.Arg295Arg	synonymous	Exon 9 of 11	ENSP00000359527.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460156 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 726446

African (AFR) AF: 0.0000300 AC: 1 AN: 33334

American (AMR) AF: 0.00 AC: 0 AN: 44464

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26040

East Asian (EAS) AF: 0.00 AC: 0 AN: 39686

South Asian (SAS) AF: 0.00 AC: 0 AN: 86150

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52990

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5760

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111424

Other (OTH) AF: 0.00 AC: 0 AN: 60308

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.52
CADD	Benign	12
DANN	Benign	0.40
PhyloP100		2.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs121912931; hg19: chr6-70990736;