What is alopecia areata? Alopecia areata is a disease that causes hair loss. In alopecia areata, the immune system attacks the structures in skin that form hair (hair follicles). Alopecia areata usually affects the head and face, though hair can be lost from any part of the body. Hair typically falls out in small, round patches about the size of a quarter. In some cases, hair loss is more extensive.

What is fibromyalgia? Fibromyalgia is a long-lasting disorder that causes pain and tenderness throughout the body. It also can cause you to feel overly tired (fatigue) and have trouble sleeping. Doctors do not fully understand what causes fibromyalgia, but people with the disorder are more sensitive to pain.

What are growth plate injuries? The growth plate is the area of tissue near the ends of long bones in children and teens that determines what length and shape the bone will be once it is done growing. Each long bone— the thigh bone, the bones in the forearm, and the bones in the hands and fingers—has at least two growth plates, one at each end. Once your child has finished growing, the growth plates close and are replaced by solid bone. The growth plates are weak areas of your child’s growing skeleton, making it easier to injure them. Injuries

What is Paget’s disease? Paget’s disease of bone is a chronic (long-lasting) disorder that causes bones to grow larger and become weaker than normal. Usually only one or a few bones have the disease. Many people with Paget’s disease do not have symptoms. However, the bone changes can cause: Bone pain. Misshapen bones. Broken bones (fractures). Problems in the joints near the bones with the disease. With treatment, many people can: Manage their symptoms. Improve pain. Control the effects of the disease.

What is osteoporosis? Osteoporosis is a disease that causes bones to become weak and brittle. This increases your risk of broken bones (fractures). Osteoporosis is a “silent” disease because you may not have symptoms. You may not even know you have the disease until you break a bone. Breaks can occur in any bone but happen most often in: Hip bones. Vertebrae in the spine. Wrist. You can take steps to help prevent osteoporosis and broken bones by: Doing weight-bearing exercises, such as walking or dancing, and lifting weights. Not drinking too much alcohol. Quitting smoking, or not starting if

What is osteonecrosis? Your bones are made up of living cells that need a blood supply to stay healthy. In osteonecrosis, blood flow to part of a bone is reduced. This causes death of bone tissue, and the bone can eventually break down and the joint will collapse. Osteonecrosis can happen to any bone, but most often it develops in the ends of long bones, such as the: Thigh bone. Upper arm bone. Less often, the bones of the elbows, ankles, feet, wrists, and hands are affected. When the disease involves part of a bone in a joint, it can

What is Raynaud’s phenomenon? Raynaud’s phenomenon is a condition that causes the blood vessels in the hands and feet to narrow, decreasing blood flow. When this happens, parts of the body—usually the fingers and toes—become cold and numb, and change color (usually, to white or blue). An attack usually happens from exposure to cold or stress.

What is vitiligo? Vitiligo is a chronic (long-lasting) disorder that causes areas of skin to lose color. When skin cells that make color are attacked and destroyed, the skin turns a milky-white color. No one knows what causes vitiligo, but it may be an autoimmune disease. In people with autoimmune diseases, the immune cells attack the body’s own healthy tissues by mistake, instead of viruses or bacteria. A person with vitiligo sometimes may have family members who also have the disease. There is no cure for vitiligo, but treatment may help skin tone appear more even.

What is pachyonychia congenita? Pachyonychia congenita (PC) is a very rare genetic disorder that affects the skin and nails. Most people have thickened nails and calluses on the bottom of the feet. Painful calluses on the soles can make walking difficult. Because of the pain, some people rely on a cane, crutches, or a wheelchair to help with walking.

What is osteopetrosis? Osteopetrosis is a rare disorder that causes bones to grow abnormally and become too dense. When this happens, bones can break easily. In addition, bones may be misshapen and large, causing other problems in the body, such as problems with: Seeing and hearing. Fighting infection. Controlling bleeding. Osteopetrosis is a genetic disease that a child inherits from their parents. The disorder may be mild to severe, and symptoms may show up early after birth or later in adulthood.