Satoyoshi syndrome is a rare syndrome characterized by progressive, painful, intermittent muscle spasms. These muscle spasms usually start between 6-15 years old. Other symptoms of the syndrome may include diarrhea and an inability of the digestive tract to absorb certain foods, especially carbohydrates (malabsorption). People affected by Satoyoshi syndrome may also have loss of hair on the head and body (alopecia universalis), short stature, and skeletal abnormalities. Women with Satoyoshi syndrome may not have a menstrual cycle (amenorrhea). In all published cases, only one person in a family has Satoyoshi syndrome. This is even true when the person with Satoyoshi syndrome comes from a large family. Satoyoshi syndrome seems to be more common in Japan. The exact cause of the syndrome is unknown, but some researchers think it may be an autoimmune disease. Satoyoshi syndrome can be diagnosed when a doctor sees symptoms that are consistent with the syndrome. The diagnosis can be confirmed by a variety of laboratory tests. Treatment for Satoyoshi syndrome includes medication to suppress the immune system.