GENE REFERENCE / HGNC:2198

COL1A2

collagen type I alpha 2 chain

protein-coding gene7q21.3Gene information

What does this gene do?

The COL1A2 gene provides instructions for making part of a large molecule called type I collagen. Collagens are a family of proteins that strengthen and support many tissues in the body, including cartilage, bone, tendon, skin, and the white part of the eye (the sclera). Type I collagen is the most abundant form of collagen in the human body.

A component of type I collagen called the pro-α2(I) chain is produced from the COL1A2 gene. Collagens begin as rope-like procollagen molecules that are each made up of three chains. Type I collagen is composed of two pro-α1(I) chains (which are produced from the COL1A1 gene) and one pro-α2(I) chain.

The triple-stranded procollagen molecules are processed by enzymes in a series of steps inside and outside the cell to create mature collagen. The collagen molecules then arrange themselves into long, thin fibrils that form stable interactions (cross-links) with one another in the spaces between cells. The cross-links result in the formation of very strong type I collagen fibers.

Source: MedlinePlus, National Library of Medicine. Source publication: 2020-08-18. Source review: 2019-11.

ClinGen reviews

ClinGen reviews the evidence linking a particular gene to a condition. Each rating below describes the strength of that link. It does not classify a variant in your DNA file.

Condition	Inheritance	Evidence
COL1A2-related Ehlers-Danlos syndromeMONDO:0100606 · Evaluated 2022-11-02	Autosomal dominant	DefinitiveSkeletal Disorders Gene Curation Expert Panel
Ehlers-Danlos syndrome, cardiac valvular typeMONDO:0009159 · Evaluated 2023-09-28	Autosomal recessive	DefinitiveSkeletal Disorders Gene Curation Expert Panel
congenital heart diseaseMONDO:0005453 · Evaluated 2024-09-09	Not specified (UD)	DisputedCongenital Heart Disease Gene Curation Expert Panel
COL1A2-related osteogenesis imperfectaMONDO:0100596 · Evaluated 2022-12-05	Autosomal dominant	DefinitiveSkeletal Disorders Gene Curation Expert Panel

ClinVar records

These numbers show what has been submitted to ClinVar. They cannot tell you how likely you are to have a condition.

Submitted alleles: 2,941
Submissions for variants in or overlapping this gene: 5,486
Submissions explicitly reporting this gene: 5,367
Alleles reported pathogenic / likely pathogenic: 803
VariationIDs with uncertain significance: 904
VariationIDs with conflicting classifications: 141

The rows count different things: alleles, submissions or VariationIDs. Their categories can overlap, so do not add them together. Pathogenic/likely pathogenic counts exclude structural variants that merely overlap a gene. A dash in the source means “not reported,” not zero.

NCBI produces the gene-summary file each week using counts recorded at the start of the month. The numbers may differ from those on the live ClinVar website. Read the field definitions ↗

View this gene in ClinVar ↗

YOUR DNA FILE

Can your DNA file tell you about COL1A2?

From a DNA test kit (such as 23andMe, AncestryDNA or MyHeritage). These kits check a fixed list of about 600,000 to 700,000 positions across your whole genome. ClinVar lists 803 alleles in COL1A2 reported as pathogenic or likely pathogenic. A kit checks only some of these positions, and often none of them.

From whole genome sequencing (a VCF file). Sequencing reads most of your genome. Your file lists the places where your DNA differs from the reference genome. Some regions are hard to sequence, including parts of some genes that have near-identical copies elsewhere, and a VCF file does not record which positions were read well.

If a variant is not in your file, that does not mean you don’t have it.

What BioDecode checks

BioDecode compares every variant in your file with ClinVar, on your own computer. For each match, it shows the ClinVar classification, the review status and the condition it was reported for. Your file is not uploaded.

A ClinVar classification applies to one particular variant and the condition it was reported for. It does not tell you about other variants in COL1A2.

BioDecode cannot fill gaps in your test, diagnose a condition or replace clinical testing.

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