There are many people who have features of connective tissue disease. However, they do not fulfill the diagnostic criteria established for any one disease. In such circumstances, they are often considered to have “undifferentiated” connective tissue disease (UCTD). Over time, people with UCTD may evolve into one of the more specific connective tissue diseases, such as lupus, Sjögren’s, or scleroderma. Color changes of hands and feet with cold exposure are known as Raynaud’s. The cause with Raynaud’s disease is unknown. Raynaud’s phenomenon is due to other conditions such as connective tissue disorders, blood vessels problems, blood disorders, neurologic disorders, and exposure to drugs, toxins, or trauma. Please read our undifferentiated connective tissue disease (UCTD) information at http://www.nationaljewish.org/disease-info/diseases/rheum/uctd/index.aspx to learn more.