PYY and Menkes disease: The gastrointestinal symptoms in both diseases are believedto be caused by gastrointestinal dysmotility (100,103).Despite this gastrointestinal dysmotility, PYY cells in the large intestine of FAP patients,both in Sweden and Japan, as well as of MD patients, were unaffected (100,102,103).It seems, therefore, that PYY does not play a significant role in these categories ofpatients.