Polycythemia vera (pol-e-sy-THEE-me-uh VEER-uh) is a type of blood cancer. It causes your bone marrow to make too many red blood cells. These excess cells …

Myelofibrosis is an uncommon type of bone marrow cancer that disrupts your body’s normal production of blood cells. Myelofibrosis causes extensive scarring in your bone …

Hereditary hemochromatosis (he-moe-kroe-muh-TOE-sis) causes your body to absorb too much iron from the food you eat. Excess iron is stored in your organs, especially your …

Rheumatoid arthritis is a chronic inflammatory disorder that can affect more than just your joints. In some people, the condition can damage a wide variety …

Psoriatic arthritis is a form of arthritis that affects some people who have psoriasis — a disease that causes red patches of skin topped with …

Psoriasis is a skin disease that causes red, itchy scaly patches, most commonly on the knees, elbows, trunk and scalp. Psoriasis is a common, long-term …

Fibrocystic breasts are composed of tissue that feels lumpy or ropelike in texture. Doctors call this nodular or glandular breast tissue. It’s not at all …

Endometriosis (en-doe-me-tree-O-sis) is an often painful disorder in which tissue similar to the tissue that normally lines the inside of your uterus — the endometrium …

Hepatitis B is a serious liver infection caused by the hepatitis B virus (HBV). For some people, hepatitis B infection becomes chronic, meaning it lasts …