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Prader-willi syndrome
Prader-Willi (PRAH-dur VIL-e) syndrome is a rare genetic condition that leads to physical, mental and behavioral problems. A key feature of Prader-Willi syndrome is a sense of being hungry all the time.
Primary lateral sclerosis
Primary lateral sclerosis (PLS) is a type of motor neuron disease. A motor neuron disease affects the nerve cells in the brain that control movement. In PLS, the breakdown of nerve cells causes weakness in the muscles that control the legs, arms and tongue.
Psoriatic arthritis
Psoriatic arthritis is a type of arthritis that can affect people who have psoriasis. Psoriasis is a skin condition that causes itchy, scaly patches on the skin. The patches may be red, purple or brown depending on your skin color. Most people get psoriasis first, sometimes years before symptoms of psoriatic arthritis start.
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Reactive arthritis
Reactive arthritis is joint pain and swelling triggered by an infection in another part of the body — most often the intestines, genitals or urinary tract.
Rheumatoid arthritis.
Rheumatoid arthritis is an ongoing, called chronic, condition that causes pain, swelling and irritation, called inflammation, in the joints. But it also can damage other parts of the body. These may include the skin, eyes, lungs, heart and blood vessels.
Rickets
Rickets is the softening and weakening of bones in children, often because of an extreme and prolonged vitamin D or calcium deficiency. Rare inherited problems also can cause rickets.
Runner’s knee
Patellofemoral (puh-tel-o-FEM-uh-rul) pain syndrome is pain at the front of the knee, around the kneecap. The kneecap also is known as the patella. Patellofemoral pain syndrome is sometimes called runner's knee. It's more common in people who run and who play sports that involve running and jumping.
