chr20-62817086-G-A

Position:

• chr20-62817086-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001853.4(COL9A3):​c.22G>A​(p.Ala8Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000113 in 1,241,062 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A8V) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000011 (0 hom.)
• Consequence: COL9A3 NM_001853.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.00400

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.1851632).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL9A3	NM_001853.4	c.22G>A	p.Ala8Thr	missense_variant	1/32	ENST00000649368.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL9A3	ENST00000649368.1	c.22G>A	p.Ala8Thr	missense_variant	1/32		NM_001853.4	P1
COL9A3	ENST00000477612.5	n.75-481G>A		intron_variant, non_coding_transcript_variant		3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.0000113 AC: 14 AN: 1241062 Hom.: 0 Cov.: 30 AF XY: 0.00000980 AC XY: 6 AN XY: 612138

Gnomad4 AFR exome AF: 0.0000803

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.000247

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000500

Gnomad4 OTH exome AF: 0.0000406

GnomAD4 genome Cov.: 33

Bravo AF: 0.0000113

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 10, 2023

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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt COL9A3 protein function. ClinVar contains an entry for this variant (Variation ID: 1915027). This variant has not been reported in the literature in individuals affected with COL9A3-related conditions. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 8 of the COL9A3 protein (p.Ala8Thr). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Benign	-0.077	T
BayesDel_noAF	Benign	-0.35
CADD	Benign	5.4
DANN	Benign	0.90
DEOGEN2	Benign	0.00013	T;T
Eigen	Benign	-0.60
Eigen_PC	Benign	-0.77
FATHMM_MKL	Benign	0.058	N
LIST_S2	Benign	0.29	.;T
M_CAP	Uncertain	0.13	D
MetaRNN	Benign	0.19	T;T
MetaSVM	Benign	-0.34	T
MutationAssessor	Benign	1.3	L;L
MutationTaster	Benign	1.0	N
PrimateAI	Uncertain	0.79	T
PROVEAN	Benign	0.97	.;N
REVEL	Benign	0.21
Sift	Benign	0.45	.;T
Sift4G	Benign	0.56	.;T
Polyphen		0.96	D;D
Vest4		0.16
MutPred		0.33		Loss of methylation at R5 (P = 0.0722);Loss of methylation at R5 (P = 0.0722);
MVP		0.64
MPC		0.068
ClinPred		0.074	T
GERP RS		1.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
Varity_R		0.019
gMVP		0.44

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

Publications

LitVar

Other links and lift over

dbSNP: rs1226702696; hg19: chr20-61448438;