In humans, collagen is found in the flesh and connective tissues. According to the U.S. National Library of Medicine and the National Institutes of Health, or NIH, more than 200 disorders can affect a person's connective tissue. Connective tissue disorders--including collagen tissue disorders--can be caused by infection, injury or genetics, although some connective tissue disorders have no known cause.
Marfan syndrome is a genetic disorder of collagen or connective tissue. According to the National Heart Lung and Blood Institute, or NHLBI, Marfan syndrome usually affects the connective tissue of a person's heart, eyes, bones, lungs and spinal cord. Common signs or characteristics of Marfan syndrome include a tall, lean build; long extremities and flexible joints; scoliosis or abnormal spinal curvature; abnormal breastbone formation; crowded teeth; and flat feet. Numerous health complications--some life-threatening--can manifest in a person with Marfan syndrome. The NHLBI notes that the most serious complications associated with Marfan syndrome affect a person's heart and blood vessels. Marfan syndrome can cause the aorta--the artery that carries oxygenated blood to the body's tissues and organs--to weaken and stretch, which is a condition called aortic aneurysm. Dissection or rupture of an aortic aneurysm can be fatal.
Ehlers-Danlos syndrome is a group of heritable collagen or connective tissue disorders. The Ehlers-Danlos National Foundation, or EDNF, a non-profit organization dedicated to creating resources for people affected by the syndrome, states that Ehlers-Danlos syndrome is caused by faulty collagen and is characterized by joint hypermobility, skin extensibility and tissue fragility. Common skin-related symptoms of Ehlers-Danlos syndrome include soft skin, fragile skin, skin that bruises easily, excessive scarring, blunted wound healing and the development of fleshy tumors over tender points in the body's tissues. Common joint-related symptoms of Ehlers-Danlos syndrome include loose or unstable joints, frequent joint dislocations, joint pain and early onset of degenerative joint disease. According to the EDNF, there are six major types of Ehlers-Danlos syndrome, and each type is classified based on its own unique signs and symptoms.
Scleroderma is a collagen or connective tissue disorder that's more common in women than men. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, a division of the NIH, it's believed that the immune system of a person with scleroderma stimulates fibroblasts--the most common cells in connective tissue--to generate excessive amounts of collagen. As fibroblasts produce collagen, the collagen forms a thick band of connective tissue that accumulates within the skin and internal organs, which can impair organ functioning. Excessive collagen production can also affect blood vessels and joints. MayoClinic.com states that the most common signs and symptoms of scleroderma include Raynaud's phenomenon or numbness, pain and discoloration in the fingers or toes, gastroesophageal reflux disease or GERD and skin changes such as swollen fingers and hands, shiny skin and thickened patches of skin.