Types and Associated Disorders
Collagen occurs in many places throughout the body. Over 90% of the collagen in the body, however, is of type one.
So far, 28 types of collagen have been identified and described. The five most common types are:
- Collagen I: skin, tendon, vascular ligature, organs, bone (main component of the organic part of bone)
- Collagen II: cartilage (main component of cartilage)
- Collagen III: reticulate (main component of reticular fibers), commonly found alongside type I.
- Collagen IV: forms bases of cell basement membrane
- Collagen V: cell surfaces, hair and placenta
Collagen-related diseases most commonly arise from genetic defects or nutritional deficiencies that affect the biosynthesis, assembly, postranslational modification, secretion, or other processes involved in normal collagen production.
| Type | Notes | Gene(s) | Disorders |
| I | This is the most abundant collagen of the human body. It is present in scar tissue, the end product when tissue heals by repair. It is found in tendons, skin, artery walls, cornea, the endomysium of myofibrils, fibrocartilage, and the organic part of bones and teeth. | COL1A1, COL1A2 | Osteogenesis imperfecta, Ehlers–Danlos syndrome, Infantile cortical hyperostosis aka Caffey's disease |
| II | Hyaline cartilage, makes up 50% of all cartilage protein. Vitreous humour of the eye. | COL2A1 | Collagenopathy, types II and XI |
| III | This is the collagen of granulation tissue, and is produced quickly by young fibroblasts before the tougher type I collagen is synthesized. Reticular fiber. Also found in artery walls, skin, intestines and the uterus | COL3A1 | Ehlers–Danlos syndrome, Dupuytren's contracture |
| IV | Basal lamina; eye lens. Also serves as part of the filtration system in capillaries and the glomeruli of nephron in the kidney. | COL4A1, COL4A2, COL4A3, COL4A4, COL4A5, COL4A6 | Alport syndrome, Goodpasture's syndrome |
| V | Most interstitial tissue, assoc. with type I, associated with placenta | COL5A1, COL5A2, COL5A3 | Ehlers–Danlos syndrome (Classical) |
| VI | Most interstitial tissue, assoc. with type I | COL6A1, COL6A2, COL6A3, COL6A5 | Ulrich myopathy, Bethlem myopathy, Atopic dermatitis |
| VII | Forms anchoring fibrils in dermoepidermal junctions | COL7A1 | Epidermolysis bullosa dystrophica |
| VIII | Some endothelial cells | COL8A1, COL8A2 | Posterior polymorphous corneal dystrophy 2 |
| IX | FACIT collagen, cartilage, assoc. with type II and XI fibrils | COL9A1, COL9A2, COL9A3 | EDM2 and EDM3 |
| X | Hypertrophic and mineralizing cartilage | COL10A1 | Schmid metaphyseal dysplasia |
| XI | Cartilage | COL11A1, COL11A2 | Collagenopathy, types II and XI |
| XII | FACIT collagen, interacts with type I containing fibrils, decorin and glycosaminoglycans | COL12A1 | – |
| XIII | Transmembrane collagen, interacts with integrin a1b1, fibronectin and components of basement membranes like nidogen and perlecan. | COL13A1 | – |
| XIV | FACIT collagen | COL14A1 | – |
| XV | – | COL15A1 | – |
| XVI | – | COL16A1 | – |
| XVII | Transmembrane collagen, also known as BP180, a 180 kDa protein | COL17A1 | Bullous pemphigoid and certain forms of junctional epidermolysis bullosa |
| XVIII | Source of endostatin | COL18A1 | – |
| XIX | FACIT collagen | COL19A1 | – |
| XX | – | COL20A1 | – |
| XXI | FACIT collagen | COL21A1 | – |
| XXII | – | COL22A1 | – |
| XXIII | MACIT collagen | COL23A1 | – |
| XXIV | – | COL24A1 | – |
| XXV | – | COL25A1 | – |
| XXVI | – | EMID2 | – |
| XXVII | – | COL27A1 | – |
| XXVIII | – | COL28A1 | – |
In addition to the above mentioned disorders, excessive deposition of collagen occurs in scleroderma.
Read more about this topic: Collagen
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