Disease genes refer to specific segments or sequences of DNA that are associated with an increased risk for developing a particular disease. These genes may contain mutations, variations or alterations in their sequence which can lead to abnormal proteins being produced, causing the body's cells and tissues not to function properly. The presence of these disease-causing gene variants is often inherited from one generation to another through family members. Identifying and studying disease genes helps researchers understand the underlying causes of various diseases, paving way for early diagnosis, prevention or treatment strategies.