mixed connective tissue disease
Mixed connective tissue disease (MCTD) is a type of connective tissue disease. With regards to clinical and imaging features, it can have significant overlap with other connective tissue diseases such as systemic lupus erythematosus and scleroderma . It is therefore classified as a type of overlap syndrome and at times it even comes under debate as to whether MCTD should exist as a distinct entity .
Mixed connective tissue disease is a rare autoimmune condition and is often defined by the presence of a ribonuclease-sensitive extractable nuclear antigen .
A prerequisite for the diagnosis of mixed connective tissue disease is the presence in the serum of high titers of antibodies against uridine-rich RNA-small nuclear ribonucleoprotein (snRNP) - anti-U1-RNP antibodies .
The presence of anti-U1-70 kd is considered a characteristic feature .
MCTD can affect various organ systems, with pulmonary and musculoskeletal being two of the key systems affected. As such these are best discussed under separate headings:
- pulmonary manifestations of mixed connective tissue disease
- musculoskeletal manifestations of mixed connective tissue disease
History and etymology
It was thought to have been first described by Gordon C Sharp and colleagues in 1972 .