MCTD vs. UCTD (Mixed Connective Tissue Disease vs. Undifferentiated Connective Tissue Disease)
Mixed connective tissue disease (MCTD), which was first described in 1972, is "classically" considered as an "overlap," or mix, of three specific connective-tissue diseases: systemic lupus erythematosus, scleroderma, and polymyositis. Patients with this pattern of illness (that is, with MCTD) have features of each of these three diseases.
Mixed connective tissue disease facts
- Connective tissues are the framework of the cells of
- Mixed connective tissue disease is an "overlap" combination of connective tissue
- Diagnosis of mixed connective tissue disease is supported by detecting abnormal
antibodies in the blood.
- Treatment of mixed connective tissue disease is directed at suppressing immune-related
inflammation of tissues.
What are connective tissues?
The connective tissues are the structural portions of our body that essentially hold the cells of the body together. These tissues form a
framework or matrix for the body. The connective tissues are
composed of two major structural molecules, collagen and elastin.
There are many different collagen proteins that vary in
amount in each tissue of the body. Elastin is another protein that
has the capability of stretching and returning to original length
like a spring. Elastin is the major component of ligaments (tissues
which attach bone to bone).
Connective tissue diseases are disorders featuring abnormalities involving the collagen and elastin. Connective tissue diseases are often characterized by a variety of immune abnormalities that are common for each particular type of illness.
What diseases characteristically affect connective tissue?
Diseases of connective tissue that are strictly inheritable (due to
genetic inheritance) include Marfan syndrome (can have tissue
abnormalities in the heart, aorta, lungs, eyes, and skeleton) and
Ehlers-Danlos syndrome (may have loose, fragile skin or loose
[hyperextensible] joints). Pseudoxanthoma
elasticum is an inherited disorder of elastin.
Other diseases of connective tissue do not have specific gene abnormalities as their sole cause. These connective tissue diseases
occur for unknown reasons. They are characterized as a group by the
presence of spontaneous overactivity of the immune system, which results in the
production of unusual antibodies in the blood.
The classic immune-related connective tissue diseases include systemic lupus erythematosus,
rheumatoid arthritis, scleroderma, polymyositis, and
dermatomyositis. Each of these diseases has a characteristic presentation
with typical clinical findings that doctors can recognize during an
examination. Each also has characteristic blood test abnormalities and
abnormal antibody patterns. However, each of these diseases can
evolve slowly or rapidly from very subtle abnormalities before
demonstrating the classic features that help in the diagnosis. When these conditions have not developed the classic features of a particular disease, doctors will often refer to the condition as "undifferentiated connective tissue disease." This implies that the characteristic features that are used to define the classic connective tissue disease are not present, but some symptoms or signs of connective disease exist. Individuals with undifferentiated connective tissue disease may never develop a fully definable condition or they may eventually develop a classic connective tissue disease.
Medically Reviewed by a Doctor on 2/18/2015