FITNESS & NUTRITION Bones/Joints/Muscles • Juvenile rheumatoid arthritis • Osteoarthritis • Rheumatoid arthritis • Bursitis • Fibromyalgia • Gout • Lupus • Osteoporosis • Sjogren's syndrome • Tendinitis • Trigger finger • Achilles tendon rupture • Back pain • Hip fracture • Rotator cuff injury • Scoliosis • Muscular dystrophy • Dislocation • Shin splints • Bunions • Muscle cramp • Polymyositis • Dermatomyositis • Sprains and strains • TMJ disorders • Scleroderma • Osgood-Schlatter disease • Frozen shoulder • Polymyalgia rheumatica • Baker's cyst • Flatfeet • Morton's neuroma • Tennis elbow • Psoriatic arthritis • Hammertoe and mallet toe • Ankylosing spondylitis • Paget's disease of bone • Reactive arthritis • Metatarsalgia • Plantar fasciitis • Spinal stenosis • Sciatica • Marfan syndrome • Neck pain • Septic arthritis • Knee pain • Stress fractures • CREST syndrome • Dislocated shoulder • Patellar tendinitis • Costochondritis • Bone spurs • Avascular necrosis • Legg-Calve-Perthes disease • Water on the knee • Mixed connective tissue disease • Kyphosis • De Quervain's tenosynovitis • Cervical spondylosis • Thumb arthritis • Ehlers-Danlos syndrome • Golfer's elbow • Pseudogout • Sacroiliitis • Dupuytren's contracture • Achilles tendinitis • Diffuse idiopathic skeletal hyperostosis (DISH) • Osteochondritis dissecans • Osteomyelitis • Ganglion cysts • Chondromalacia patella • Chronic exertional compartment syndrome • Adult Still's disease • Rickets • Growth plate fractures • Greenstick fractures

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Mixed connective tissue disease (MCTD) is a rare autoimmune disorder that causes signs and symptoms of other connective tissue diseases. People with mixed connective tissue disease experience features of three other diseases — lupus, scleroderma and polymyositis. For this reason, mixed connective tissue disease is sometimes referred to as an overlap disease.

Signs and symptoms of these three other diseases usually don't appear all at once. This makes diagnosing mixed connective tissue disease somewhat complicated. Often people with mixed connective tissue disease are first diagnosed with lupus. As the disease progresses and other signs and symptoms become apparent, the diagnosis is corrected.

Mixed connective tissue disease occurs most often in women and is usually diagnosed in young adults in their 20s and 30s. Children have also been diagnosed with mixed connective tissue disease.

Mixed connective tissue disease is somewhat of a controversial term among arthritis specialists (rheumatologists). Some question whether mixed connective tissue disease is its own specific disease or whether it's a precursor to another connective tissue disease.

Mixed connective tissue disease doesn't have a unique set of signs and symptoms. Instead, people with mixed connective tissue disease usually have signs and symptoms of lupus, scleroderma and polymyositis, including:

• Fatigue
• Muscle weakness
• Joint pain
• Joint swelling
• Swollen fingers
• Mild fever
• Raynaud's phenomenon — blood vessel spasms that interrupt blood flow to the fingers, toes, ears and nose

Doctors don't know what causes mixed connective tissue disease. The disease is part of a larger group of diseases known as autoimmune disorders. When you have an autoimmune disorder, your immune system — the part of your body responsible for fighting off disease — mistakes normal, healthy cells for intruders. As a result, healthy tissue in your body is damaged, causing signs and symptoms of disease.

It isn't clear what causes your immune system to attack your body. Doctors believe a complex mix of viruses, chemicals and genetic factors may be at play.

Doctors don't know what puts you at risk of mixed connective tissue disease. Some research shows the disease may occur more frequently in people with a family history of connective tissue diseases. Other findings show an increased risk in people exposed to certain chemicals, including vinyl chloride and silica. More research is needed to confirm these findings.

Signs and symptoms of mixed connective tissue disease usually begin mildly and may not prompt you to seek medical attention. But if signs and symptoms become bothersome or interfere with your daily routine, make an appointment with your doctor.

Also see your doctor if you've been diagnosed with lupus or another connective tissue disease and you begin developing new signs and symptoms.

Your doctor may suspect mixed connective tissue disease based on your signs and symptoms. He or she will conduct a physical exam to look for signs such as swollen hands and painful, swollen joints.

A blood test determines whether you have a certain antibody in your blood that indicates mixed connective tissue disease. The presence of this specific antibody — called U1-RNP — can confirm your doctor's suspicions.

Mixed connective tissue disease usually develops slowly, making it difficult to diagnose. As your signs and symptoms evolve over time — sometimes many years — your diagnosis may change. Many people are first diagnosed with lupus and later re-diagnosed with mixed connective tissue disease. Others begin with a diagnosis of mixed connective tissue disease only to later find they have lupus or another connective tissue disorder.

Mixed connective tissue disease and its treatment can lead to serious complications, including:

• Pulmonary hypertension. High blood pressure affecting the arteries in your lungs (pulmonary hypertension) is the most common cause of death in people with mixed connective tissue disease. You might experience difficulty breathing or chest pain if you have pulmonary hypertension. People with mixed connective tissue disease usually need to take medications to control pulmonary hypertension.
• Heart disease. People with mixed connective tissue disease are at risk of developing heart conditions, including enlargement of parts of the heart and inflammation around the heart (pericarditis). Your doctor may routinely monitor your heart with an electrocardiogram.
• Side effects of long-term steroid use. Steroids are commonly used to manage the signs and symptoms of mixed connective tissue disease. While these medications are effective, they don't come without risks. If you take steroids, your doctor will likely monitor you for adverse effects, such as bone loss due to osteoporosis or avascular necrosis, muscle weakness and infection.
• Pregnancy complications. Women with mixed connective tissue disease may experience flares during pregnancy. Babies born to women with mixed connective tissue disease are at risk of being born with a low birth weight. If you're planning to become pregnant, talk with your doctor about this risk.

No cure exists for mixed connective tissue disease, although treatments can help manage the signs and symptoms of the disease. Your treatment may vary from another person's because your signs and symptoms may be different.

While no standard treatment exists, the most common treatment for mixed connective tissue disease is corticosteroids, such as prednisone.

People with mild forms of mixed connective tissue disease may not need any treatment. You may require treatment only during flares or you may require constant medication. Work with your doctor to ensure that your signs and symptoms are adequately controlled.

Living with a chronic disease that has no cure requires effective coping skills. Consider trying to:

• Find out as much as you can about mixed connective tissue disease. Learn as much as you can about the disease. Ask your doctor and other health care team members for assistance in locating reliable resources. The more you know about the disease, the easier it is to understand what's happening to your body.
• Take care of yourself. Control your health as best you can. Eat a balanced diet with plenty of fruits and vegetables. Get exercise on days you feel up to it. Keeping your body healthy makes you better able to deal with the daily stress of living with a chronic illness. And it better prepares you to cope with your next flare.
• Seek support from others. Social support helps you cope with the stress of mixed connective tissue disease. Ask your doctor about support groups in your area for people with chronic illnesses. Go online to connect with other people living with mixed connective tissue disease.