The cause of scleroderma is unknown. It is not contagious, so you can't catch it from someone or give it to anyone. It is not inherited or passed on from one generation to the next, except in rare instances.
 
In scleroderma it is known that the body produces too much of a protein called collagen (cah lah jen). This excess collagen is deposited in the skin and in body organs. This causes thickening and hardening of the skin and affects the function of internal organs.
 
Scientists think the body's immune system plays a part in causing excess collagen deposits.  The immune system, your body's natural defense against disease, normally develops antibodies. Antibodies are protective substances in the blood that fight off invading organisms (like harmful bacteria and viruses). But sometimes the antibodies attack the body's healthy tissue instead. This abnormal process is called an autoimmune reaction.
 
It is known that the small blood vessels are damaged in scleroderma. There may be a connection between the build-up of excess collagen and blood vessel changes. Researchers are trying to find the answer to this as well as to the immune system's role in the disease.