Connective tissue disease refers to a group of disorders involving the protein-rich tissue that supports organs and other parts of the body. Examples of connective tissue are fat, bone, and cartilage. These disorders often involve the joints, muscles, and skin, but they can also involve other organs and organ systems, including the eyes, heart, lungs, kidneys, gastrointestinal tract, and blood vessels. There are more than 200 disorders that affect the connective tissue. Causes and specific symptoms vary by the different types.
Inherited Disorders of Connective Tissue
Some connective tissue diseases -- often called heritable disorders of connective tissue (HDCTs) -- are the result of changes in certain genes. Many of these are quite rare. Following are some of the more common ones.
Ehlers-Danlos syndrome (EDS). Actually a group of more than 10 disorders, EDS is characterized by over-flexible joints, stretchy skin, and abnormal growth of scar tissue. Symptoms can range from mild to disabling. Depending on the specific form of EDS, other symptoms may include:
Epidermolysis bullosa (EB). People with EB have skin that is so fragile that it tears or blisters as a result of a minor bump, stumble, or even friction from clothing. Some forms of EB may involve the digestive tract, the respiratory tract, the muscles, or the bladder. Caused by defects of several proteins in the skin, EB is usually evident at birth.
Marfan syndrome. Marfan syndrome affects the bones, ligaments, eyes, heart, and blood vessels. People with Marfan syndrome tend to be tall and have extremely long bones and thin "spider-like" fingers and toes. Other problems may include eye problems due to abnormal placement of the eye lens and enlargement of the aorta (the largest artery in the body), which can lead to a fatal rupture. Marfan syndrome is caused by mutations in the gene that regulates the structure of a protein called fibrillin-1.
Osteogenesis imperfecta. Osteogenesis imperfecta is a condition of brittle bones, low muscle mass, and lax joints and ligaments. There are several types of this condition. Specific symptoms depend on the specific type and may include:
- Blue or gray tint to the whites of the eyes
- Thin skin
- Curved spine
- Breathing problems
- Hearing loss
- Teeth that break easily
The disease occurs when a mutation in two genes responsible for type 1 collagen reduces the amount or quality of the protein. Type 1 collagen is important to the structure of bone and skin.
For other forms of connective tissue disease, the cause is not known. In some cases, researchers believe the disorder may be triggered by something in the environment of people who may be genetically susceptible. In these diseases, the body's normally protective immune system produces antibodies that target the body's own tissues for attack.
These diseases include the following.
Polymyositis and dermatomyositis. These are two related diseases in which there is inflammation of the muscles (polymyositis) and skin (dermatomyositis). Symptoms of both diseases can include:
- Muscle weakness
- Difficulty swallowing
- Shortness of breath
- Weight loss
People with dermatomyositis may also have a skin involvement around the eyes and the hands.
Rheumatoid arthritis (RA). Rheumatoid arthritis is a disease in which the immune system attacks the thin membrane (called the synovium) lining the joints, causing pain, stiffness, warmth and swelling of the joints, and inflammation throughout the body. Other symptoms may include:
RA can lead to permanent joint damage and deformity.
Scleroderma. Scleroderma is a term for a group of disorders that causes thick, tight skin, buildup of scar tissue, and organ damage. These disorders fall into two general categories: localized scleroderma and systemic sclerosis.
Localized scleroderma is confined to the skin and, sometimes, the muscle beneath it. Systemic sclerosis also involves the blood vessels and major organs.
Sjögren's syndrome. Sjögren's syndrome is a chronic disease in which the immune system attacks the moisture-producing glands, such as those of the eyes and mouth. The effects can range from mildly uncomfortable to debilitating. Although dry eyes and mouth are the main symptoms of Sjögren's, many people also experience extreme fatigue and joint pain. The condition also increases the risk of lymphoma and may cause problems with the kidneys, lungs, blood vessels, and digestive system as well as nerve problems.
Systemic lupus erythematosus. Systemic lupus erythematosus (SLE or simply lupus) is a disease characterized by inflammation of the joints, skin, and internal organs. Symptoms may include:
Vasculitis. Vasculitis is a general term for more than 20 different conditions characterized by inflammation of the blood vessels. These can affect blood flow to the organs and other body tissues. Vasculitis can involve any of the blood vessels.
Mixed connective tissue disease. People with MCTD have some features characteristic of several diseases, including lupus, scleroderma, polymyositis or dermatomyositis, and rheumatoid arthritis. When this occurs, doctors often make the diagnosis of mixed connective tissue disease.
While many people with mixed connective tissue disease have mild symptoms, others may experience life-threatening complications.