Most individuals with Williams syndrome experience GI issues at some point, especially abnormal bowel movement patterns (mainly constipation and related problems such as rectal prolapse & hemorrhoids) and bouts of abdominal pain. Research suggests that GI symptoms can be significant in Williams syndrome.  Common issues include: reflux, abdominal pain, constipation, diarrhea, irritable bowel syndrome, and dysmotility.  Less common but significant issues include diverticulitis (at much younger age than is common in the general population)celiac disease, and gluten intolerance.  Weight management, a healthy diet (rich in fruits and vegetables), LOTS of water and regular exercise are the best things you can do to minimize these concerns.