Mixed connective tissue disease
Mixed connective tissue disease (MCTD), also known as Sharp syndrome, is a rare autoimmune disorder that causes inflammation and damage to tissues in your body. It can affect any organ or system in the body, including the skin, joints, heart, lungs, and kidneys.
MCTD symptoms are thought to be an overlap of three other autoimmune diseases, which are systemic sclerosis, systemic lupus erythematosus, and polymyositis. Affected people may present with fatigue, arthralgia, Raynaud's phenomenon (recurrent vasospasm of the fingers and toes, usually triggered by the stress of cold), multiple joint pain, and gastroesophageal reflux.