Mixed Connective Tissue Disease (MCTD)

Abstract Children with mixed connective tissue disease (MCTD) are antinuclear antibody (ANA)-positive. At one time this disease was thought to be a milder version of SLE. To understand this disease, it is necessary to understand that it was defined “backwards.” A physician named Gordon Sharp noted an unusual laboratory finding in some patients who were antinuclear antibody (ANA)-positive. When he went back and looked at the patients who had this finding, they were most often “atypical” SLE patients. These patients differed from typical SLE patients in having more arthritis, more rash, more lung disease, and less kidney disease. Since many of these patients were also positive for rheumatoid factor (see Chapter 24) and had more arthritis than typical SLE patients, they were thought of as having “mixed” disease. Thus, the name was chosen to reflect this. It took only a short time once the disease was described in adults to realize that there were children with the same pattern of findings.