Which Type of disease produces symptoms for which no physiological or anatomical cause can be identified?

The type of disease that produces symptoms without an identifiable physiological or anatomical cause is known as a functional or psychosomatic disorder. These conditions manifest with real symptoms but are primarily influenced by psychological factors rather than identifiable physical issues. Examples include conditions like irritable bowel syndrome (IBS) and certain types of chronic pain syndromes. The symptoms can significantly impact a person's quality of life, even though traditional medical tests may show no clear abnormalities.