Mixed connective tissue disease (MCTD)

Mixed connective tissue disease combines features of more than one connective tissue disease, often lupus, scleroderma, and inflammatory muscle disease, in the same person, and is distinguished from these separate conditions by a particular antibody pattern directed against U1-RNP. The immune system is thought to drive this overlapping process, and the clinical picture commonly includes Raynaud's phenomenon, swollen or puffy hands, joint pain, and swallowing difficulty, though the exact combination varies.

A Norwegian national multicentre survey, one of the few population-based studies of this condition, estimated the point prevalence of adult-onset MCTD at about 3.8 per 100,000 people and the annual incidence at roughly 2.1 per million, figures that support its reputation as the least common of the connective tissue diseases. Estimates vary across populations and diagnostic criteria.

Common signs

A mix that commonly includes Raynaud's, swollen or puffy hands, joint pain, muscle weakness, fatigue, and swallowing difficulty. Because it overlaps several conditions, the exact picture varies, and lung involvement can develop in some people.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.