Most of us have heard of collagen- a protein that is present in all connective tissues of the body (skin, bones, hair, tendons etc.) It provides strength and structure to these tissues.
It is also present in the blood vessels and the intestines. There are around 28 types of collagen, different diseases are associated with the defects in each of these.
The three most common types are-
• Type I collagen: This is the most abundant type in the human body, and is present in the skin, bones and tendons. One of the major disorders associated with a defect in Type 1 collagen is Osteogenesis imperfecta, also known as brittle bone disease. Individuals with OI can have bone pains, bowed legs and other physical deformities such as scoliosis, which is an abnormal bending of the spine.
• Type II collagen: It is found in cartilage and in the discs between each vertebrae. A defect in this type leads to Stickler syndrome, which is characterised by flattened facial features, a small jaw and eye problems such as severe near-sightedness.
• Type III collagen- It is found along with Type I collagen and is additionally present in blood vessels, which makes it important for cardiovascular health. Defective Type III collagen is associated with Ehlers Danlos syndrome which can show up as various different presentations, some being hypermobility of the joints and cardiovascular defects such as mitral valve prolapse. It can affect different systems of the body thus having different signs and symptoms.
MBH/AB
The body’s structural backbone is actually collagen, which supports everything from joint flexibility to bone strength and skin elasticity. This complicated subject is simple to understand thanks to your explanation of the three main types and the disorders that are associated with them. The fact that one protein family has such a wide range of functions in different systems is astounding. We are reminded of the true interconnectedness of our body’s structures by posts such as this one! 
