Mixed Connective Tissue Disease - Mixed Connective Tissue Disease

In medicine, mixed connective tissue disease (also known as Sharp's syndrome), commonly abbreviated as MCTD, is an autoimmune disease in which the body's defense system attacks itself. It was characterized in 1972, and the term was introduced by Leroy in 1980.

It is sometimes said to be the same as undifferentiated connective tissue disease, but other experts specifically reject this idea because undifferentiated connective tissue disease is not necessarily associated with serum antibodies directed against the U1-RNP, and MCTD is associated with a more clearly defined set of signs/symptoms.

Signs and symptoms

MCTD combines features of scleroderma, myositis, systemic lupus erythematosus, and rheumatoid arthritis (with some sources adding polymyositis, dermatomyositis, and inclusion body myositis) and is thus considered an overlap syndrome.

MCTD commonly causes:

• joint pain/swelling,
• malaise,
• Raynaud phenomenon,
• muscle inflammation, and
• sclerodactyly (thickening of the skin of the pads of the fingers)

Diagnosis

Distinguishing laboratory characteristics are a positive, speckled anti-nuclear antibody and an anti-U1-RNP antibody.

Cause

It has been associated with HLA-DR4.

Prognosis

The prognosis of mixed connective tissue disease is in one third of cases worse than that of systemic lupus erythematosus (SLE). In spite of prednisone treatment, this disease is progressive and may in many cases evolve into a progressive systemic sclerosis (PSS), also referred to as diffuse cutaneous systemic scleroderma (dcSSc) which has a poor outcome. In some cases though the disease is mild and may only need aspirin as a treatment and may go into remission where no Anti-U1-RNP antibodies are detected, but that is rare or within 30% of cases.

Most deaths from MCTD are due to heart failure caused by Pulmonary Arterial Hypertension (PAH).