Collagen vascular diseases are a variety of conditions that involve disorders of collagen. Collagen is a tough, glue-like protein that makes up 30% of body protein. It shapes the structure of tendons, bones, and connective tissues. Problems with the immune system can affect these structures, and lead to conditions such as Rheumatoid Arthritis, Scleroderma, and Systemic Lupus Erythematosus (SLE).