NM_001852.4:c.1003C>A

Variant names:

• chr1-40307451-G-T
• rs2228567
• NM_001852.4:c.1003C>A

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_001852.4(COL9A2):​c.1003C>A​(p.Leu335Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,564 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. L335V) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: COL9A2 NM_001852.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.394
• Publications: 28 publications found

Genes affected

COL9A2 (HGNC:2218): (collagen type IX alpha 2 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. This chain is unusual in that, unlike the other two type IX alpha chains, it contains a covalently attached glycosaminoglycan side chain. Mutations in this gene are associated with multiple epiphyseal dysplasia. [provided by RefSeq, Jul 2008]

COL9A2 Gene-Disease associations (from GenCC):

• epiphyseal dysplasia, multiple, 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• Stickler syndrome, type 5

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, PanelApp Australia, Labcorp Genetics (formerly Invitae), Ambry Genetics, Genomics England PanelApp
• 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: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL9A2	NM_001852.4	c.1003C>A	p.Leu335Ile	missense_variant	Exon 19 of 32	ENST00000372748.8	NP_001843.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL9A2	ENST00000372748.8	c.1003C>A	p.Leu335Ile	missense_variant	Exon 19 of 32	1	NM_001852.4	ENSP00000361834.3
COL9A2	ENST00000482722.5	n.1306C>A		non_coding_transcript_exon_variant	Exon 18 of 31	1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461564 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727054

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44666

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86196

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53394

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111882

Other (OTH) AF: 0.00 AC: 0 AN: 60356

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 775

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Oct 08, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces leucine, which is neutral and non-polar, with isoleucine, which is neutral and non-polar, at codon 335 of the COL9A2 protein (p.Leu335Ile). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with COL9A2-related conditions. ClinVar contains an entry for this variant (Variation ID: 1897980). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt COL9A2 protein function with a negative predictive value of 95%. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.094
BayesDel_addAF	Uncertain	0.015	T
BayesDel_noAF	Benign	-0.22
CADD	Benign	18
DANN	Uncertain	0.98
DEOGEN2	Benign	0.13	T
Eigen	Benign	0.0019
Eigen_PC	Benign	0.0082
FATHMM_MKL	Benign	0.75	D
LIST_S2	Benign	0.84	T
M_CAP	Uncertain	0.093	D
MetaRNN	Uncertain	0.42	T
MetaSVM	Uncertain	0.14	D
MutationAssessor	Benign	1.3	L
PhyloP100		0.39
PrimateAI	Uncertain	0.50	T
PROVEAN	Benign	-0.51	N
REVEL	Benign	0.23
Sift	Uncertain	0.027	D
Sift4G	Benign	0.19	T
Polyphen		0.90	P
Vest4		0.23
MutPred		0.35		Loss of catalytic residue at L335 (P = 0.1212);
MVP		0.88
MPC		0.71
ClinPred		0.72	D
GERP RS		3.0
Varity_R		0.13
gMVP		0.13
Mutation Taster		=98/2	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs2228567; hg19: chr1-40773123;